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index 8aacd1d42a..bd58d4a25a 100644
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@@ -1,7 +1,7 @@
Basics
-
- Compilation
+
+ Programming Tools
- This will include things like: compilation, makefiles, .mk
- files, basic debugging, linking, secure programming
- guidelines, style(9), CVS, diff, patch, etc.
+ This chapter was written by James Raynard.
+ Modifications for the Developer's Handbook by Murray Stokely.
+
+
+ Synopsis
+
+ This document is an introduction to using some of the
+ programming tools supplied with FreeBSD, although much of it
+ will be applicable to many other versions of Unix. It does
+ not attempt to describe coding in any
+ detail. Most of the document assumes little or no previous
+ programming knowledge, although it is hoped that most
+ programmers will find something of value in it
+
+
+
+ Introduction
+
+ FreeBSD offers an excellent development environment.
+ Compilers for C, C++, and Fortran and an assembler come with the
+ basic system, not to mention a Perl interpreter and classic Unix
+ tools such as sed and awk.
+ If that is not enough, there are many more compilers and
+ interpreters in the Ports collection. FreeBSD is very
+ compatible with standards such as POSIX and
+ ANSI C, as well with its own BSD heritage, so
+ it is possible to write applications that will compile and run
+ with little or no modification on a wide range of
+ platforms.
+
+ However, all this power can be rather overwhelming at
+ first if you've never written programs on a Unix platform
+ before. This document aims to help you get up and running,
+ without getting too deeply into more advanced topics. The
+ intention is that this document should give you enough of the
+ basics to be able to make some sense of the
+ documentation.
+
+ Most of the document requires little or no knowledge of
+ programming, although it does assume a basic competence with
+ using Unix and a willingness to learn!
+
+
+
+
+ Introduction to Programming
+
+ A program is a set of instructions that tell the computer
+ to do various things; sometimes the instruction it has to
+ perform depends on what happened when it performed a previous
+ instruction. This section gives an overview of the two main
+ ways in which you can give these instructions, or
+ commands as they are usually called. One way
+ uses an interpreter, the other a
+ compiler. As human languages are too
+ difficult for a computer to understand in an unambiguous way,
+ commands are usually written in one or other languages specially
+ designed for the purpose.
+
+
+ Interpreters
+
+ With an interpreter, the language comes as an environment,
+ where you type in commands at a prompt and the environment
+ executes them for you. For more complicated programs, you can
+ type the commands into a file and get the interpreter to load
+ the file and execute the commands in it. If anything goes
+ wrong, many interpreters will drop you into a debugger to help
+ you track down the problem.
+
+ The advantage of this is that you can see the results of
+ your commands immediately, and mistakes can be corrected
+ readily. The biggest disadvantage comes when you want to
+ share your programs with someone. They must have the same
+ interpreter, or you must have some way of giving it to them,
+ and they need to understand how to use it. Also users may not
+ appreciate being thrown into a debugger if they press the
+ wrong key! From a performance point of view, interpreters can
+ use up a lot of memory, and generally do not generate code as
+ efficiently as compilers.
+
+ In my opinion, interpreted languages are the best way to
+ start if you have not done any programming before. This kind
+ of environment is typically found with languages like Lisp,
+ Smalltalk, Perl and Basic. It could also be argued that the
+ Unix shell (sh, csh) is itself an
+ interpreter, and many people do in fact write shell
+ scripts to help with various
+ housekeeping tasks on their machine. Indeed, part
+ of the original Unix philosophy was to provide lots of small
+ utility programs that could be linked together in shell
+ scripts to perform useful tasks.
+
+
+
+ Interpreters available with FreeBSD
+
+ Here is a list of interpreters that are available as
+ FreeBSD
+ packages, with a brief discussion of some of the
+ more popular interpreted languages.
+
+ To get one of these packages, all you need to do is to
+ click on the hotlink for the package, then run
+
+ &prompt.root; pkg_add package name
+
+
+ as root. Obviously, you will need to have a fully
+ functional FreeBSD 2.1.0 or later system for the package to
+ work!
+
+
+
+ BASIC
+
+
+ Short for Beginner's All-purpose Symbolic
+ Instruction Code. Developed in the 1950s for teaching
+ University students to program and provided with every
+ self-respecting personal computer in the 1980s,
+ BASIC has been the first programming
+ language for many programmers. It's also the foundation
+ for Visual Basic.
+
+ The Bywater
+ Basic Interpreter and the Phil
+ Cockroft's Basic Interpreter (formerly Rabbit
+ Basic) are available as FreeBSD FreeBSD
+ packages
+
+
+
+
+ Lisp
+
+
+ A language that was developed in the late 1950s as
+ an alternative to the number-crunching
+ languages that were popular at the time. Instead of
+ being based on numbers, Lisp is based on lists; in fact
+ the name is short for List Processing.
+ Very popular in AI (Artificial Intelligence)
+ circles.
+
+ Lisp is an extremely powerful and sophisticated
+ language, but can be rather large and unwieldy.
+
+ FreeBSD has GNU
+ Common Lisp available as a package.
+
+
+
+
+ Perl
+
+
+ Very popular with system administrators for writing
+ scripts; also often used on World Wide Web servers for
+ writing CGI scripts.
+
+ The latest version (version 5) comes with FreeBSD.
+
+
+
+
+ Scheme
+
+
+ A dialect of Lisp that is rather more compact and
+ cleaner than Common Lisp. Popular in Universities as it
+ is simple enough to teach to undergraduates as a first
+ language, while it has a high enough level of
+ abstraction to be used in research work.
+
+ FreeBSD has packages of the Elk
+ Scheme Interpreter, the MIT
+ Scheme Interpreter and the SCM
+ Scheme Interpreter.
+
+
+
+
+ Icon
+
+
+ The
+ Icon Programming Language.
+
+
+
+
+ Logo
+
+
+ Brian
+ Harvey's LOGO Interpreter.
+
+
+
+
+ Python
+
+
+ The
+ Python Object-Oriented Programming
+ Language
+
+
+
+
+
+
+ Compilers
+
+ Compilers are rather different. First of all, you write
+ your code in a file (or files) using an editor. You then run
+ the compiler and see if it accepts your program. If it did
+ not compile, grit your teeth and go back to the editor; if it
+ did compile and gave you a program, you can run it either at a
+ shell command prompt or in a debugger to see if it works
+ properly.
+
+
+ If you run it in the shell, you may get a core
+ dump.
+
+
+ Obviously, this is not quite as direct as using an
+ interpreter. However it allows you to do a lot of things
+ which are very difficult or even impossible with an
+ interpreter, such as writing code which interacts closely with
+ the operating system—or even writing your own operating
+ system! It's also useful if you need to write very efficient
+ code, as the compiler can take its time and optimise the code,
+ which would not be acceptable in an interpreter. And
+ distributing a program written for a compiler is usually more
+ straightforward than one written for an interpreter—you
+ can just give them a copy of the executable, assuming they
+ have the same operating system as you.
+
+ Compiled languages include Pascal, C and C++. C and C++
+ are rather unforgiving languages, and best suited to more
+ experienced programmers; Pascal, on the other hand, was
+ designed as an educational language, and is quite a good
+ language to start with. Unfortunately, FreeBSD doesn't have
+ any Pascal support, except for a Pascal-to-C converter in the
+ ports.
+
+ As the edit-compile-run-debug cycle is rather tedious when
+ using separate programs, many commercial compiler makers have
+ produced Integrated Development Environments
+
+ (IDEs for short). FreeBSD does not have an
+ IDE as such; however it is possible to use Emacs
+ for this purpose. This is discussed in .
+
+
+
+
+
+
+
+ Compiling with <command>cc</command>
+
+ This section deals only with the GNU compiler for C and C++,
+ since that comes with the base FreeBSD system. It can be
+ invoked by either cc or gcc. The
+ details of producing a program with an interpreter vary
+ considerably between interpreters, and are usually well covered
+ in the documentation and on-line help for the
+ interpreter.
+
+ Once you've written your masterpiece, the next step is to
+ convert it into something that will (hopefully!) run on FreeBSD.
+ This usually involves several steps, each of which is done by a
+ separate program.
+
+
+
+ Pre-process your source code to remove comments and do
+ other tricks like expanding macros in C.
+
+
+
+ Check the syntax of your code to see if you have obeyed
+ the rules of the language. If you have not, it will
+ complain!
+
+
+
+ Convert the source code into assembly
+ language—this is very close to machine code, but still
+ understandable by humans. Allegedly.
+
+
+ To be strictly accurate, cc converts the
+ source code into its own, machine-independent
+ p-code instead of assembly language at
+ this stage.
+
+
+
+
+ Convert the assembly language into machine
+ code—yep, we are talking bits and bytes, ones and
+ zeros here.
+
+
+
+ Check that you have used things like functions and
+ global variables in a consistent way. For example, if you
+ have called a non-existent function, it will
+ complain.
+
+
+
+ If you are trying to produce an executable from several
+ source code files, work out how to fit them all
+ together.
+
+
+
+ Work out how to produce something that the system's
+ run-time loader will be able to load into memory and
+ run.
+
+
+
+ Finally, write the executable on the file system.
+
+
+
+ The word compiling is often used to refer to
+ just steps 1 to 4—the others are referred to as
+ linking. Sometimes step 1 is referred to as
+ pre-processing and steps 3-4 as
+ assembling.
+
+ Fortunately, almost all this detail is hidden from you, as
+ cc is a front end that manages calling all these
+ programs with the right arguments for you; simply typing
+
+ &prompt.user; cc foobar.c
+
+
+ will cause foobar.c to be compiled by all the
+ steps above. If you have more than one file to compile, just do
+ something like
+
+ &prompt.user; cc foo.c bar.c
+
+
+ Note that the syntax checking is just that—checking
+ the syntax. It will not check for any logical mistakes you may
+ have made, like putting the program into an infinite loop, or
+ using a bubble sort when you meant to use a binary
+ sort.
+
+
+ In case you didn't know, a binary sort is an efficient
+ way of sorting things into order and a bubble sort
+ isn't.
+
+
+ There are lots and lots of options for cc, which
+ are all in the man page. Here are a few of the most important
+ ones, with examples of how to use them.
+
+
+
+
+
+
+ The output name of the file. If you do not use this
+ option, cc will produce an executable called
+ a.out.
+
+
+ The reasons for this are buried in the mists of
+ history.
+
+
+
+ &prompt.user; cc foobar.c executable is a.out
+&prompt.user; cc -o foobar foobar.c executable is foobar
+
+
+
+
+
+
+
+
+
+ Just compile the file, do not link it. Useful for toy
+ programs where you just want to check the syntax, or if
+ you are using a Makefile.
+
+
+ &prompt.user; cc -c foobar.c
+
+
+
+ This will produce an object file (not an
+ executable) called foobar.o. This
+ can be linked together with other object files into an
+ executable.
+
+
+
+
+
+
+
+ Create a debug version of the executable. This makes
+ the compiler put information into the executable about
+ which line of which source file corresponds to which
+ function call. A debugger can use this information to show
+ the source code as you step through the program, which is
+ very useful; the disadvantage is that
+ all this extra information makes the program much bigger.
+ Normally, you compile with while you
+ are developing a program and then compile a release
+ version without when you're
+ satisfied it works properly.
+
+
+ &prompt.user; cc -g foobar.c
+
+
+
+ This will produce a debug version of the
+ program.
+
+
+ Note, we didn't use the flag
+ to specify the executable name, so we will get an
+ executable called a.out.
+ Producing a debug version called
+ foobar is left as an exercise for
+ the reader!
+
+
+
+
+
+
+
+
+ Create an optimised version of the executable. The
+ compiler performs various clever tricks to try and produce
+ an executable that runs faster than normal. You can add a
+ number after the to specify a higher
+ level of optimisation, but this often exposes bugs in the
+ compiler's optimiser. For instance, the version of
+ cc that comes with the 2.1.0 release of
+ FreeBSD is known to produce bad code with the
+ option in some circumstances.
+
+ Optimisation is usually only turned on when compiling
+ a release version.
+
+
+ &prompt.user; cc -O -o foobar foobar.c
+
+
+
+ This will produce an optimised version of
+ foobar.
+
+
+
+
+ The following three flags will force cc
+ to check that your code complies to the relevant international
+ standard, often referred to as the ANSI
+ standard, though strictly speaking it is an
+ ISO standard.
+
+
+
+
+
+
+ Enable all the warnings which the authors of
+ cc believe are worthwhile. Despite the
+ name, it will not enable all the warnings
+ cc is capable of.
+
+
+
+
+
+
+
+ Turn off most, but not all, of the
+ non-ANSI C features provided by
+ cc. Despite the name, it does not
+ guarantee strictly that your code will comply to the
+ standard.
+
+
+
+
+
+
+
+ Turn off all
+ cc's non-ANSI C
+ features.
+
+
+
+
+ Without these flags, cc will allow you to
+ use some of its non-standard extensions to the standard. Some
+ of these are very useful, but will not work with other
+ compilers—in fact, one of the main aims of the standard is
+ to allow people to write code that will work with any compiler
+ on any system. This is known as portable
+ code.
+
+ Generally, you should try to make your code as portable as
+ possible, as otherwise you may have to completely re-write the
+ program later to get it to work somewhere else—and who
+ knows what you may be using in a few years time?
+
+
+ &prompt.user; cc -Wall -ansi -pedantic -o foobar foobar.c
+
+
+
+ This will produce an executable foobar
+ after checking foobar.c for standard
+ compliance.
+
+
+
+
+
+
+ Specify a function library to be used during when
+ linking.
+
+ The most common example of this is when compiling a
+ program that uses some of the mathematical functions in C.
+ Unlike most other platforms, these are in a separate
+ library from the standard C one and you have to tell the
+ compiler to add it.
+
+ The rule is that if the library is called
+ libsomething.a,
+ you give cc the argument
+ .
+ For example, the math library is
+ libm.a, so you give
+ cc the argument .
+ A common gotcha with the math library is
+ that it has to be the last library on the command
+ line.
+
+
+ &prompt.user; cc -o foobar foobar.c -lm
+
+
+
+ This will link the math library functions into
+ foobar.
+
+ If you are compiling C++ code, you need to add
+ , or if
+ you are using FreeBSD 2.2 or later, to the command line
+ argument to link the C++ library functions.
+ Alternatively, you can run c++ instead
+ of cc, which does this for you.
+ c++ can also be invoked as
+ g++ on FreeBSD.
+
+
+ &prompt.user; cc -o foobar foobar.cc -lg++For FreeBSD 2.1.6 and earlier
+&prompt.user; cc -o foobar foobar.cc -lstdc++For FreeBSD 2.2 and later
+&prompt.user; c++ -o foobar foobar.cc
+
+
+
+ Each of these will both produce an executable
+ foobar from the C++ source file
+ foobar.cc. Note that, on Unix
+ systems, C++ source files traditionally end in
+ .C, .cxx or
+ .cc, rather than the
+ MS-DOS style
+ .cpp (which was already used for
+ something else). gcc used to rely on
+ this to work out what kind of compiler to use on the
+ source file; however, this restriction no longer applies,
+ so you may now call your C++ files
+ .cpp with impunity!
+
+
+
+
+
+ Common <command>cc</command> Queries and Problems
+
+
+
+
+ I am trying to write a program which uses the
+ sin() function and I get an error
+ like this. What does it mean?
+
+
+ /var/tmp/cc0143941.o: Undefined symbol `_sin' referenced from text segment
+
+
+
+
+
+ When using mathematical functions like
+ sin(), you have to tell
+ cc to link in the math library, like
+ so:
+
+
+ &prompt.user; cc -o foobar foobar.c -lm
+
+
+
+
+
+
+
+ All right, I wrote this simple program to practice
+ using . All it does is raise 2.1 to
+ the power of 6.
+
+
+ #include <stdio.h>
+
+int main() {
+ float f;
+
+ f = pow(2.1, 6);
+ printf("2.1 ^ 6 = %f\n", f);
+ return 0;
+}
+
+
+
+ and I compiled it as:
+
+
+ &prompt.user; cc temp.c -lm
+
+
+
+ like you said I should, but I get this when I run
+ it:
+
+
+ &prompt.user; ./a.out
+2.1 ^ 6 = 1023.000000
+
+
+
+ This is not the right answer!
+ What is going on?
+
+
+
+ When the compiler sees you call a function, it
+ checks if it has already seen a prototype for it. If it
+ has not, it assumes the function returns an
+ int, which is definitely not what you want
+ here.
+
+
+
+
+
+ So how do I fix this?
+
+
+
+ The prototypes for the mathematical functions are in
+ math.h. If you include this file,
+ the compiler will be able to find the prototype and it
+ will stop doing strange things to your
+ calculation!
+
+
+ #include <math.h>
+#include <stdio.h>
+
+int main() {
+...
+
+
+
+ After recompiling it as you did before, run
+ it:
+
+
+ &prompt.user; ./a.out
+2.1 ^ 6 = 85.766121
+
+
+
+ If you are using any of the mathematical functions,
+ always include
+ math.h and remember to link in the
+ math library.
+
+
+
+
+
+ I compiled a file called
+ foobar.c and I cannot find an
+ executable called foobar. Where's
+ it gone?
+
+
+
+ Remember, cc will call the
+ executable a.out unless you tell it
+ differently. Use the
+
+ option:
+
+
+ &prompt.user; cc -o foobar foobar.c
+
+
+
+
+
+
+
+ OK, I have an executable called
+ foobar, I can see it when I run
+ ls, but when I type in
+ foobar at the command prompt it tells
+ me there is no such file. Why can it not find
+ it?
+
+
+
+ Unlike MS-DOS, Unix does not
+ look in the current directory when it is trying to find
+ out which executable you want it to run, unless you tell
+ it to. Either type ./foobar, which
+ means run the file called
+ foobar in the current
+ directory, or change your PATH environment
+ variable so that it looks something like
+
+
+ bin:/usr/bin:/usr/local/bin:.
+
+
+
+ The dot at the end means look in the current
+ directory if it is not in any of the
+ others.
+
+
+
+
+
+ I called my executable test,
+ but nothing happens when I run it. What is going
+ on?
+
+
+
+ Most Unix systems have a program called
+ test in /usr/bin
+ and the shell is picking that one up before it gets to
+ checking the current directory. Either type:
+
+
+ &prompt.user; ./test
+
+
+
+ or choose a better name for your program!
+
+
+
+
+
+ I compiled my program and it seemed to run all right
+ at first, then there was an error and it said something
+ about core dumped. What does that
+ mean?
+
+
+
+ The name core dump dates back
+ to the very early days of Unix, when the machines used
+ core memory for storing data. Basically, if the program
+ failed under certain conditions, the system would write
+ the contents of core memory to disk in a file called
+ core, which the programmer could
+ then pore over to find out what went wrong.
+
+
+
+
+
+ Fascinating stuff, but what I am supposed to do
+ now?
+
+
+
+ Use gdb to analyse the core (see
+ ).
+
+
+
+
+
+ When my program dumped core, it said something about
+ a segmentation fault. What's
+ that?
+
+
+
+ This basically means that your program tried to
+ perform some sort of illegal operation on memory; Unix
+ is designed to protect the operating system and other
+ programs from rogue programs.
+
+ Common causes for this are:
+
+
+
+ Trying to write to a NULL
+ pointer, eg
+
+ char *foo = NULL;
+strcpy(foo, "bang!");
+
+
+
+
+ Using a pointer that hasn't been initialised,
+ eg
+
+ char *foo;
+strcpy(foo, "bang!");
+
+
+ The pointer will have some random value that,
+ with luck, will point into an area of memory that
+ isn't available to your program and the kernel will
+ kill your program before it can do any damage. If
+ you're unlucky, it'll point somewhere inside your
+ own program and corrupt one of your data structures,
+ causing the program to fail mysteriously.
+
+
+
+ Trying to access past the end of an array,
+ eg
+
+ int bar[20];
+bar[27] = 6;
+
+
+
+
+ Trying to store something in read-only memory,
+ eg
+
+ char *foo = "My string";
+strcpy(foo, "bang!");
+
+
+ Unix compilers often put string literals like
+ "My string" into read-only areas
+ of memory.
+
+
+
+ Doing naughty things with
+ malloc() and
+ free(), eg
+
+ char bar[80];
+free(bar);
+
+
+ or
+
+ char *foo = malloc(27);
+free(foo);
+free(foo);
+
+
+
+
+ Making one of these mistakes will not always lead to
+ an error, but they are always bad practice. Some
+ systems and compilers are more tolerant than others,
+ which is why programs that ran well on one system can
+ crash when you try them on an another.
+
+
+
+
+
+ Sometimes when I get a core dump it says
+ bus error. It says in my Unix
+ book that this means a hardware problem, but the
+ computer still seems to be working. Is this
+ true?
+
+
+
+ No, fortunately not (unless of course you really do
+ have a hardware problem…). This is usually
+ another way of saying that you accessed memory in a way
+ you shouldn't have.
+
+
+
+
+
+ This dumping core business sounds as though it could
+ be quite useful, if I can make it happen when I want to.
+ Can I do this, or do I have to wait until there's an
+ error?
+
+
+
+ Yes, just go to another console or xterm, do
+
+ &prompt.user; ps
+
+
+ to find out the process ID of your program, and
+ do
+
+ &prompt.user; kill -ABRT pid
+
+
+ where
+ pid is
+ the process ID you looked up.
+
+ This is useful if your program has got stuck in an
+ infinite loop, for instance. If your program happens to
+ trap SIGABRT, there are several other
+ signals which have a similar effect.
+
+
+
+
+
+
+
+ Make
+
+
+ What is <command>make</command>?
+
+ When you're working on a simple program with only one or
+ two source files, typing in
+
+ &prompt.user; cc file1.c file2.c
+
+
+ is not too bad, but it quickly becomes very tedious when
+ there are several files—and it can take a while to
+ compile, too.
+
+ One way to get around this is to use object files and only
+ recompile the source file if the source code has changed. So
+ we could have something like:
+
+ &prompt.user; cc file1.o file2.o … file37.c &hellip
+
+
+ if we'd changed file37.c, but not any
+ of the others, since the last time we compiled. This may
+ speed up the compilation quite a bit, but doesn't solve the
+ typing problem.
+
+ Or we could write a shell script to solve the typing
+ problem, but it would have to re-compile everything, making it
+ very inefficient on a large project.
+
+ What happens if we have hundreds of source files lying
+ about? What if we're working in a team with other people who
+ forget to tell us when they've changed one of their source
+ files that we use?
+
+ Perhaps we could put the two solutions together and write
+ something like a shell script that would contain some kind of
+ magic rule saying when a source file needs compiling. Now all
+ we need now is a program that can understand these rules, as
+ it's a bit too complicated for the shell.
+
+ This program is called make. It reads
+ in a file, called a makefile, that
+ tells it how different files depend on each other, and works
+ out which files need to be re-compiled and which ones don't.
+ For example, a rule could say something like if
+ fromboz.o is older than
+ fromboz.c, that means someone must have
+ changed fromboz.c, so it needs to be
+ re-compiled. The makefile also has rules telling
+ make how to re-compile the source file,
+ making it a much more powerful tool.
+
+ Makefiles are typically kept in the same directory as the
+ source they apply to, and can be called
+ makefile, Makefile
+ or MAKEFILE. Most programmers use the
+ name Makefile, as this puts it near the
+ top of a directory listing, where it can easily be
+ seen.
+
+
+ They don't use the MAKEFILE form
+ as block capitals are often used for documentation files
+ like README.
+
+
+
+
+ Example of using <command>make</command>
+
+ Here's a very simple make file:
+
+ foo: foo.c
+ cc -o foo foo.c
+
+
+ It consists of two lines, a dependency line and a creation
+ line.
+
+ The dependency line here consists of the name of the
+ program (known as the target), followed
+ by a colon, then whitespace, then the name of the source file.
+ When make reads this line, it looks to see
+ if foo exists; if it exists, it compares
+ the time foo was last modified to the
+ time foo.c was last modified. If
+ foo does not exist, or is older than
+ foo.c, it then looks at the creation line
+ to find out what to do. In other words, this is the rule for
+ working out when foo.c needs to be
+ re-compiled.
+
+ The creation line starts with a tab (press
+ the tab key) and then the command you would
+ type to create foo if you were doing it
+ at a command prompt. If foo is out of
+ date, or does not exist, make then executes
+ this command to create it. In other words, this is the rule
+ which tells make how to re-compile
+ foo.c.
+
+ So, when you type make, it will
+ make sure that foo is up to date with
+ respect to your latest changes to foo.c.
+ This principle can be extended to
+ Makefiles with hundreds of
+ targets—in fact, on FreeBSD, it is possible to compile
+ the entire operating system just by typing make
+ world in the appropriate directory!
+
+ Another useful property of makefiles is that the targets
+ don't have to be programs. For instance, we could have a make
+ file that looks like this:
+
+ foo: foo.c
+ cc -o foo foo.c
+
+install:
+ cp foo /home/me
+
+
+ We can tell make which target we want to make by
+ typing:
+
+ &prompt.user; make target
+
+
+ make will then only look at that target
+ and ignore any others. For example, if we type
+ make foo with the makefile above, make
+ will ignore the install target.
+
+ If we just type make on its own,
+ make will always look at the first target and then stop
+ without looking at any others. So if we typed
+ make here, it will just go to the
+ foo target, re-compile
+ foo if necessary, and then stop without
+ going on to the install target.
+
+ Notice that the install target doesn't
+ actually depend on anything! This means that the command on
+ the following line is always executed when we try to make that
+ target by typing make install. In this
+ case, it will copy foo into the user's
+ home directory. This is often used by application makefiles,
+ so that the application can be installed in the correct
+ directory when it has been correctly compiled.
+
+ This is a slightly confusing subject to try and explain.
+ If you don't quite understand how make
+ works, the best thing to do is to write a simple program like
+ hello world and a make file like the one above
+ and experiment. Then progress to using more than one source
+ file, or having the source file include a header file. The
+ touch command is very useful here—it
+ changes the date on a file without you having to edit
+ it.
+
+
+
+ FreeBSD Makefiles
+
+ Makefiles can be rather complicated to write. Fortunately,
+ BSD-based systems like FreeBSD come with some very powerful
+ ones as part of the system. One very good example of this is
+ the FreeBSD ports system. Here's the essential part of a
+ typical ports Makefile:
+
+ MASTER_SITES= ftp://freefall.cdrom.com/pub/FreeBSD/LOCAL_PORTS/
+DISTFILES= scheme-microcode+dist-7.3-freebsd.tgz
+
+.include <bsd.port.mk>
+
+
+ Now, if we go to the directory for this port and type
+ make, the following happens:
+
+
+
+ A check is made to see if the source code for this
+ port is already on the system.
+
+
+
+ If it isn't, an FTP connection to the URL in
+ MASTER_SITES is set up to download the
+ source.
+
+
+
+ The checksum for the source is calculated and compared
+ it with one for a known, good, copy of the source. This
+ is to make sure that the source was not corrupted while in
+ transit.
+
+
+
+ Any changes required to make the source work on
+ FreeBSD are applied—this is known as
+ patching.
+
+
+
+ Any special configuration needed for the source is
+ done. (Many Unix program distributions try to work out
+ which version of Unix they are being compiled on and which
+ optional Unix features are present—this is where
+ they are given the information in the FreeBSD ports
+ scenario).
+
+
+
+ The source code for the program is compiled. In
+ effect, we change to the directory where the source was
+ unpacked and do make—the
+ program's own make file has the necessary information to
+ build the program.
+
+
+
+ We now have a compiled version of the program. If we
+ wish, we can test it now; when we feel confident about the
+ program, we can type make install.
+ This will cause the program and any supporting files it
+ needs to be copied into the correct location; an entry is
+ also made into a package database, so
+ that the port can easily be uninstalled later if we change
+ our mind about it.
+
+
+
+ Now I think you'll agree that's rather impressive for a
+ four line script!
+
+ The secret lies in the last line, which tells
+ make to look in the system makefile called
+ bsd.port.mk. It's easy to overlook this
+ line, but this is where all the clever stuff comes
+ from—someone has written a makefile that tells
+ make to do all the things above (plus a
+ couple of other things I didn't mention, including handling
+ any errors that may occur) and anyone can get access to that
+ just by putting a single line in their own make file!
+
+ If you want to have a look at these system makefiles,
+ they're in /usr/share/mk, but it's
+ probably best to wait until you've had a bit of practice with
+ makefiles, as they are very complicated (and if you do look at
+ them, make sure you have a flask of strong coffee
+ handy!)
+
+
+
+ More advanced uses of <command>make</command>
+
+ Make is a very powerful tool, and can
+ do much more than the simple example above shows.
+ Unfortunately, there are several different versions of
+ make, and they all differ considerably.
+ The best way to learn what they can do is probably to read the
+ documentation—hopefully this introduction will have
+ given you a base from which you can do this.
+
+ The version of make that comes with FreeBSD is the
+ Berkeley make; there is a tutorial
+ for it in /usr/share/doc/psd/12.make. To
+ view it, do
+
+ &prompt.user; zmore paper.ascii.gz
+
+
+ in that directory.
+
+ Many applications in the ports use GNU
+ make, which has a very good set of
+ info pages. If you have installed any of these
+ ports, GNU make will automatically
+ have been installed as gmake. It's also
+ available as a port and package in its own right.
+
+ To view the info pages for GNU
+ make, you will have to edit the
+ dir file in the
+ /usr/local/info directory to add an entry
+ for it. This involves adding a line like
+
+ * Make: (make). The GNU Make utility.
+
+
+ to the file. Once you have done this, you can type
+ info and then select
+ make from the menu (or in
+ Emacs, do C-h
+ i).
+
+
+
+
+ Debugging
+
+
+ The Debugger
+
+ The debugger that comes with FreeBSD is called
+ gdb (GNU
+ debugger). You start it up by typing
+
+ &prompt.user; gdb progname
+
+
+ although most people prefer to run it inside
+ Emacs. You can do this by:
+
+ M-x gdb RET progname RET
+
+
+ Using a debugger allows you to run the program under more
+ controlled circumstances. Typically, you can step through the
+ program a line at a time, inspect the value of variables,
+ change them, tell the debugger to run up to a certain point
+ and then stop, and so on. You can even attach to a program
+ that's already running, or load a core file to investigate why
+ the program crashed. It's even possible to debug the kernel,
+ though that's a little trickier than the user applications
+ we'll be discussing in this section.
+
+ gdb has quite good on-line help, as
+ well as a set of info pages, so this section will concentrate
+ on a few of the basic commands.
+
+ Finally, if you find its text-based command-prompt style
+ off-putting, there's a graphical front-end for it xxgdb in the ports
+ collection.
+
+ This section is intended to be an introduction to using
+ gdb and does not cover specialised topics
+ such as debugging the kernel.
+
+
+
+ Running a program in the debugger
+
+ You'll need to have compiled the program with the
+ option to get the most out of using
+ gdb. It will work without, but you'll only
+ see the name of the function you're in, instead of the source
+ code. If you see a line like:
+
+ … (no debugging symbols found) …
+
+
+ when gdb starts up, you'll know that
+ the program wasn't compiled with the
+ option.
+
+ At the gdb prompt, type
+ break main. This will tell the
+ debugger to skip over the preliminary set-up code in the
+ program and start at the beginning of your code. Now type
+ run to start the program—it will
+ start at the beginning of the set-up code and then get stopped
+ by the debugger when it calls main().
+ (If you've ever wondered where main()
+ gets called from, now you know!).
+
+ You can now step through the program, a line at a time, by
+ pressing n. If you get to a function call,
+ you can step into it by pressing s. Once
+ you're in a function call, you can return from stepping into a
+ function call by pressing f. You can also
+ use up and down to take
+ a quick look at the caller.
+
+ Here's a simple example of how to spot a mistake in a
+ program with gdb. This is our program
+ (with a deliberate mistake):
+
+ #include <stdio.h>
+
+int bazz(int anint);
+
+main() {
+ int i;
+
+ printf("This is my program\n");
+ bazz(i);
+ return 0;
+}
+
+int bazz(int anint) {
+ printf("You gave me %d\n", anint);
+ return anint;
+}
+
+
+ This program sets i to be
+ 5 and passes it to a function
+ bazz() which prints out the number we
+ gave it.
+
+ When we compile and run the program we get
+
+ &prompt.user; cc -g -o temp temp.c
+&prompt.user; ./temp
+This is my program
+anint = 4231
+
+
+ That wasn't what we expected! Time to see what's going
+ on!
+
+ &prompt.user; gdb temp
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) break main Skip the set-up code
+Breakpoint 1 at 0x160f: file temp.c, line 9. gdb puts breakpoint at main()
+(gdb) run Run as far as main()
+Starting program: /home/james/tmp/temp Program starts running
+
+Breakpoint 1, main () at temp.c:9 gdb stops at main()
+(gdb) n Go to next line
+This is my program Program prints out
+(gdb) s step into bazz()
+bazz (anint=4231) at temp.c:17 gdb displays stack frame
+(gdb)
+
+
+ Hang on a minute! How did anint get to be
+ 4231? Didn't we set it to be
+ 5 in main()? Let's
+ move up to main() and have a look.
+
+ (gdb) up Move up call stack
+#1 0x1625 in main () at temp.c:11 gdb displays stack frame
+(gdb) p i Show us the value of i
+$1 = 4231 gdb displays 4231
+
+
+ Oh dear! Looking at the code, we forgot to initialise
+ i. We meant to put
+
+ …
+main() {
+ int i;
+
+ i = 5;
+ printf("This is my program\n");
+&hellip
+
+
+ but we left the i=5; line out. As we
+ didn't initialise i, it had whatever number
+ happened to be in that area of memory when the program ran,
+ which in this case happened to be
+ 4231.
+
+
+ gdb displays the stack frame every
+ time we go into or out of a function, even if we're using
+ up and down to move
+ around the call stack. This shows the name of the function
+ and the values of its arguments, which helps us keep track
+ of where we are and what's going on. (The stack is a
+ storage area where the program stores information about the
+ arguments passed to functions and where to go when it
+ returns from a function call).
+
+
+
+
+ Examining a core file
+
+ A core file is basically a file which contains the
+ complete state of the process when it crashed. In the
+ good old days, programmers had to print out hex
+ listings of core files and sweat over machine code manuals,
+ but now life is a bit easier. Incidentally, under FreeBSD and
+ other 4.4BSD systems, a core file is called
+ progname.core instead of just
+ core, to make it clearer which program a
+ core file belongs to.
+
+ To examine a core file, start up gdb in
+ the usual way. Instead of typing break or
+ run, type
+
+ (gdb) core progname.core
+
+
+ If you're not in the same directory as the core file,
+ you'll have to do dir
+ /path/to/core/file first.
+
+ You should see something like this:
+
+ &prompt.user; gdb a.out
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) core a.out.core
+Core was generated by `a.out'.
+Program terminated with signal 11, Segmentation fault.
+Cannot access memory at address 0x7020796d.
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+(gdb)
+
+
+ In this case, the program was called
+ a.out, so the core file is called
+ a.out.core. We can see that the program
+ crashed due to trying to access an area in memory that was not
+ available to it in a function called
+ bazz.
+
+ Sometimes it's useful to be able to see how a function was
+ called, as the problem could have occurred a long way up the
+ call stack in a complex program. The bt
+ command causes gdb to print out a
+ back-trace of the call stack:
+
+ (gdb) bt
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+#1 0xefbfd888 in end ()
+#2 0x162c in main () at temp.c:11
+(gdb)
+
+
+ The end() function is called when a
+ program crashes; in this case, the bazz()
+ function was called from main().
+
+
+
+ Attaching to a running program
+
+ One of the neatest features about gdb
+ is that it can attach to a program that's already running. Of
+ course, that assumes you have sufficient permissions to do so.
+ A common problem is when you are stepping through a program
+ that forks, and you want to trace the child, but the debugger
+ will only let you trace the parent.
+
+ What you do is start up another gdb,
+ use ps to find the process ID for the
+ child, and do
+
+ (gdb) attach pid
+
+
+ in gdb, and then debug as usual.
+
+ That's all very well, you're probably
+ thinking, but by the time I've done that, the child
+ process will be over the hill and far away. Fear
+ not, gentle reader, here's how to do it (courtesy of the
+ gdb info pages):
+
+ &hellip
+if ((pid = fork()) < 0) /* _Always_ check this */
+ error();
+else if (pid == 0) { /* child */
+ int PauseMode = 1;
+
+ while (PauseMode)
+ sleep(10); /* Wait until someone attaches to us */
+ &hellip
+} else { /* parent */
+ &hellip
+
+
+ Now all you have to do is attach to the child, set
+ PauseMode to 0, and wait
+ for the sleep() call to return!
+
+
+
+
+ Using Emacs as a Development Environment
+
+
+ Emacs
+
+ Unfortunately, Unix systems don't come with the kind of
+ everything-you-ever-wanted-and-lots-more-you-didn't-in-one-gigantic-package
+ integrated development environments that other systems
+ have.
+
+
+ At least, not unless you pay out very large sums of
+ money.
+
+
+ However, it is possible to set up your own environment. It
+ may not be as pretty, and it may not be quite as integrated,
+ but you can set it up the way you want it. And it's free.
+ And you have the source to it.
+
+ The key to it all is Emacs. Now there are some people who
+ loathe it, but many who love it. If you're one of the former,
+ I'm afraid this section will hold little of interest to you.
+ Also, you'll need a fair amount of memory to run it—I'd
+ recommend 8MB in text mode and 16MB in X as the bare minimum
+ to get reasonable performance.
+
+ Emacs is basically a highly customisable
+ editor—indeed, it has been customised to the point where
+ it's more like an operating system than an editor! Many
+ developers and sysadmins do in fact spend practically all
+ their time working inside Emacs, leaving it only to log
+ out.
+
+ It's impossible even to summarise everything Emacs can do
+ here, but here are some of the features of interest to
+ developers:
+
+
+
+ Very powerful editor, allowing search-and-replace on
+ both strings and regular expressions (patterns), jumping
+ to start/end of block expression, etc, etc.
+
+
+
+ Pull-down menus and online help.
+
+
+
+ Language-dependent syntax highlighting and
+ indentation.
+
+
+
+ Completely customisable.
+
+
+
+ You can compile and debug programs within
+ Emacs.
+
+
+
+ On a compilation error, you can jump to the offending
+ line of source code.
+
+
+
+ Friendly-ish front-end to the info
+ program used for reading GNU hypertext documentation,
+ including the documentation on Emacs itself.
+
+
+
+ Friendly front-end to gdb, allowing
+ you to look at the source code as you step through your
+ program.
+
+
+
+ You can read Usenet news and mail while your program
+ is compiling.
+
+
+
+ And doubtless many more that I've overlooked.
+
+ Emacs can be installed on FreeBSD using the Emacs
+ port.
+
+ Once it's installed, start it up and do C-h
+ t to read an Emacs tutorial—that means
+ hold down the control key, press
+ h, let go of the control
+ key, and then press t. (Alternatively, you
+ can you use the mouse to select Emacs
+ Tutorial from the Help
+ menu).
+
+ Although Emacs does have menus, it's well worth learning
+ the key bindings, as it's much quicker when you're editing
+ something to press a couple of keys than to try and find the
+ mouse and then click on the right place. And, when you're
+ talking to seasoned Emacs users, you'll find they often
+ casually throw around expressions like M-x
+ replace-s RET foo RET bar RET so it's
+ useful to know what they mean. And in any case, Emacs has far
+ too many useful functions for them to all fit on the menu
+ bars.
+
+ Fortunately, it's quite easy to pick up the key-bindings,
+ as they're displayed next to the menu item. My advice is to
+ use the menu item for, say, opening a file until you
+ understand how it works and feel confident with it, then try
+ doing C-x C-f. When you're happy with that, move on to
+ another menu command.
+
+ If you can't remember what a particular combination of
+ keys does, select Describe Key from
+ the Help menu and type it in—Emacs
+ will tell you what it does. You can also use the
+ Command Apropos menu item to find
+ out all the commands which contain a particular word in them,
+ with the key binding next to it.
+
+ By the way, the expression above means hold down the
+ Meta key, press x, release
+ the Meta key, type
+ replace-s (short for
+ replace-string—another feature of
+ Emacs is that you can abbreviate commands), press the
+ return key, type foo
+ (the string you want replaced), press the
+ return key, type bar (the string you want to
+ replace foo with) and press
+ return again. Emacs will then do the
+ search-and-replace operation you've just requested.
+
+ If you're wondering what on earth the
+ Meta key is, it's a special key that many
+ Unix workstations have. Unfortunately, PC's don't have one,
+ so it's usually the alt key (or if you're
+ unlucky, the escape key).
+
+ Oh, and to get out of Emacs, do C-x C-c
+ (that means hold down the control key, press
+ x, press c and release the
+ control key). If you have any unsaved files
+ open, Emacs will ask you if you want to save them. (Ignore
+ the bit in the documentation where it says
+ C-z is the usual way to leave
+ Emacs—that leaves Emacs hanging around in the
+ background, and is only really useful if you're on a system
+ which doesn't have virtual terminals).
+
+
+
+ Configuring Emacs
+
+ Emacs does many wonderful things; some of them are built
+ in, some of them need to be configured.
+
+ Instead of using a proprietary macro language for
+ configuration, Emacs uses a version of Lisp specially adapted
+ for editors, known as Emacs Lisp. This can be quite useful if
+ you want to go on and learn something like Common Lisp, as
+ it's considerably smaller than Common Lisp (although still
+ quite big!).
+
+ The best way to learn Emacs Lisp is to download the Emacs
+ Tutorial
+
+ However, there's no need to actually know any Lisp to get
+ started with configuring Emacs, as I've included a sample
+ .emacs file, which should be enough to
+ get you started. Just copy it into your home directory and
+ restart Emacs if it's already running; it will read the
+ commands from the file and (hopefully) give you a useful basic
+ setup.
+
+
+
+ A sample <filename>.emacs</filename> file
+
+ Unfortunately, there's far too much here to explain it in
+ detail; however there are one or two points worth
+ mentioning.
+
+
+
+ Everything beginning with a ; is a comment
+ and is ignored by Emacs.
+
+
+
+ In the first line, the
+ -*- Emacs-Lisp -*- is so that
+ we can edit the .emacs file itself
+ within Emacs and get all the fancy features for editing
+ Emacs Lisp. Emacs usually tries to guess this based on
+ the filename, and may not get it right for
+ .emacs.
+
+
+
+ The tab key is bound to an
+ indentation function in some modes, so when you press the
+ tab key, it will indent the current line of code. If you
+ want to put a tab character in whatever
+ you're writing, hold the control key down
+ while you're pressing the tab key.
+
+
+
+ This file supports syntax highlighting for C, C++,
+ Perl, Lisp and Scheme, by guessing the language from the
+ filename.
+
+
+
+ Emacs already has a pre-defined function called
+ next-error. In a compilation output
+ window, this allows you to move from one compilation error
+ to the next by doing M-n; we define a
+ complementary function,
+ previous-error, that allows you to go
+ to a previous error by doing M-p. The
+ nicest feature of all is that C-c C-c
+ will open up the source file in which the error occurred
+ and jump to the appropriate line.
+
+
+
+ We enable Emacs's ability to act as a server, so that
+ if you're doing something outside Emacs and you want to
+ edit a file, you can just type in
+
+ &prompt.user; emacsclient filename
+
+
+ and then you can edit the file in your
+ Emacs!
+
+
+ Many Emacs users set their EDITOR environment to
+ emacsclient so this happens every
+ time they need to edit a file.
+
+
+
+
+
+ A sample <filename>.emacs</filename> file
+
+ ;; -*-Emacs-Lisp-*-
+
+;; This file is designed to be re-evaled; use the variable first-time
+;; to avoid any problems with this.
+(defvar first-time t
+ "Flag signifying this is the first time that .emacs has been evaled")
+
+;; Meta
+(global-set-key "\M- " 'set-mark-command)
+(global-set-key "\M-\C-h" 'backward-kill-word)
+(global-set-key "\M-\C-r" 'query-replace)
+(global-set-key "\M-r" 'replace-string)
+(global-set-key "\M-g" 'goto-line)
+(global-set-key "\M-h" 'help-command)
+
+;; Function keys
+(global-set-key [f1] 'manual-entry)
+(global-set-key [f2] 'info)
+(global-set-key [f3] 'repeat-complex-command)
+(global-set-key [f4] 'advertised-undo)
+(global-set-key [f5] 'eval-current-buffer)
+(global-set-key [f6] 'buffer-menu)
+(global-set-key [f7] 'other-window)
+(global-set-key [f8] 'find-file)
+(global-set-key [f9] 'save-buffer)
+(global-set-key [f10] 'next-error)
+(global-set-key [f11] 'compile)
+(global-set-key [f12] 'grep)
+(global-set-key [C-f1] 'compile)
+(global-set-key [C-f2] 'grep)
+(global-set-key [C-f3] 'next-error)
+(global-set-key [C-f4] 'previous-error)
+(global-set-key [C-f5] 'display-faces)
+(global-set-key [C-f8] 'dired)
+(global-set-key [C-f10] 'kill-compilation)
+
+;; Keypad bindings
+(global-set-key [up] "\C-p")
+(global-set-key [down] "\C-n")
+(global-set-key [left] "\C-b")
+(global-set-key [right] "\C-f")
+(global-set-key [home] "\C-a")
+(global-set-key [end] "\C-e")
+(global-set-key [prior] "\M-v")
+(global-set-key [next] "\C-v")
+(global-set-key [C-up] "\M-\C-b")
+(global-set-key [C-down] "\M-\C-f")
+(global-set-key [C-left] "\M-b")
+(global-set-key [C-right] "\M-f")
+(global-set-key [C-home] "\M-<")
+(global-set-key [C-end] "\M->")
+(global-set-key [C-prior] "\M-<")
+(global-set-key [C-next] "\M->")
+
+;; Mouse
+(global-set-key [mouse-3] 'imenu)
+
+;; Misc
+(global-set-key [C-tab] "\C-q\t") ; Control tab quotes a tab.
+(setq backup-by-copying-when-mismatch t)
+
+;; Treat 'y' or <CR> as yes, 'n' as no.
+(fset 'yes-or-no-p 'y-or-n-p)
+ (define-key query-replace-map [return] 'act)
+ (define-key query-replace-map [?\C-m] 'act)
+
+;; Load packages
+(require 'desktop)
+(require 'tar-mode)
+
+;; Pretty diff mode
+(autoload 'ediff-buffers "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files-remote "ediff"
+ "Intelligent Emacs interface to diff")
+
+(if first-time
+ (setq auto-mode-alist
+ (append '(("\\.cpp$" . c++-mode)
+ ("\\.hpp$" . c++-mode)
+ ("\\.lsp$" . lisp-mode)
+ ("\\.scm$" . scheme-mode)
+ ("\\.pl$" . perl-mode)
+ ) auto-mode-alist)))
+
+;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+(defvar font-lock-mode-keyword-alist
+ '((c++-c-mode . c-font-lock-keywords)
+ (perl-mode . perl-font-lock-keywords))
+ "Associations between modes and keywords")
+
+(defun font-lock-auto-mode-select ()
+ "Automatically select font-lock-mode if the current major mode is
+in font-lock-auto-mode-list"
+ (if (memq major-mode font-lock-auto-mode-list)
+ (progn
+ (font-lock-mode t))
+ )
+ )
+
+(global-set-key [M-f1] 'font-lock-fontify-buffer)
+
+;; New dabbrev stuff
+;(require 'new-dabbrev)
+(setq dabbrev-always-check-other-buffers t)
+(setq dabbrev-abbrev-char-regexp "\\sw\\|\\s_")
+(add-hook 'emacs-lisp-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'c-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'text-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) t)
+ (set (make-local-variable 'dabbrev-case-replace) t)))
+
+;; C++ and C mode...
+(defun my-c++-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c++-mode-map "\C-ce" 'c-comment-edit)
+ (setq c++-auto-hungry-initial-state 'none)
+ (setq c++-delete-function 'backward-delete-char)
+ (setq c++-tab-always-indent t)
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c++-empty-arglist-indent 4))
+
+(defun my-c-mode-hook ()
+ (setq tab-width 4)
+ (define-key c-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c-mode-map "\C-ce" 'c-comment-edit)
+ (setq c-auto-hungry-initial-state 'none)
+ (setq c-delete-function 'backward-delete-char)
+ (setq c-tab-always-indent t)
+;; BSD-ish indentation style
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c-brace-offset -4)
+ (setq c-argdecl-indent 0)
+ (setq c-label-offset -4))
+
+;; Perl mode
+(defun my-perl-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (setq perl-indent-level 4)
+ (setq perl-continued-statement-offset 4))
+
+;; Scheme mode...
+(defun my-scheme-mode-hook ()
+ (define-key scheme-mode-map "\C-m" 'reindent-then-newline-and-indent))
+
+;; Emacs-Lisp mode...
+(defun my-lisp-mode-hook ()
+ (define-key lisp-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key lisp-mode-map "\C-i" 'lisp-indent-line)
+ (define-key lisp-mode-map "\C-j" 'eval-print-last-sexp))
+
+;; Add all of the hooks...
+(add-hook 'c++-mode-hook 'my-c++-mode-hook)
+(add-hook 'c-mode-hook 'my-c-mode-hook)
+(add-hook 'scheme-mode-hook 'my-scheme-mode-hook)
+(add-hook 'emacs-lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'perl-mode-hook 'my-perl-mode-hook)
+
+;; Complement to next-error
+(defun previous-error (n)
+ "Visit previous compilation error message and corresponding source code."
+ (interactive "p")
+ (next-error (- n)))
+
+;; Misc...
+(transient-mark-mode 1)
+(setq mark-even-if-inactive t)
+(setq visible-bell nil)
+(setq next-line-add-newlines nil)
+(setq compile-command "make")
+(setq suggest-key-bindings nil)
+(put 'eval-expression 'disabled nil)
+(put 'narrow-to-region 'disabled nil)
+(put 'set-goal-column 'disabled nil)
+
+;; Elisp archive searching
+(autoload 'format-lisp-code-directory "lispdir" nil t)
+(autoload 'lisp-dir-apropos "lispdir" nil t)
+(autoload 'lisp-dir-retrieve "lispdir" nil t)
+(autoload 'lisp-dir-verify "lispdir" nil t)
+
+;; Font lock mode
+(defun my-make-face (face colour &optional bold)
+ "Create a face from a colour and optionally make it bold"
+ (make-face face)
+ (copy-face 'default face)
+ (set-face-foreground face colour)
+ (if bold (make-face-bold face))
+ )
+
+(if (eq window-system 'x)
+ (progn
+ (my-make-face 'blue "blue")
+ (my-make-face 'red "red")
+ (my-make-face 'green "dark green")
+ (setq font-lock-comment-face 'blue)
+ (setq font-lock-string-face 'bold)
+ (setq font-lock-type-face 'bold)
+ (setq font-lock-keyword-face 'bold)
+ (setq font-lock-function-name-face 'red)
+ (setq font-lock-doc-string-face 'green)
+ (add-hook 'find-file-hooks 'font-lock-auto-mode-select)
+
+ (setq baud-rate 1000000)
+ (global-set-key "\C-cmm" 'menu-bar-mode)
+ (global-set-key "\C-cms" 'scroll-bar-mode)
+ (global-set-key [backspace] 'backward-delete-char)
+ ; (global-set-key [delete] 'delete-char)
+ (standard-display-european t)
+ (load-library "iso-transl")))
+
+;; X11 or PC using direct screen writes
+(if window-system
+ (progn
+ ;; (global-set-key [M-f1] 'hilit-repaint-command)
+ ;; (global-set-key [M-f2] [?\C-u M-f1])
+ (setq hilit-mode-enable-list
+ '(not text-mode c-mode c++-mode emacs-lisp-mode lisp-mode
+ scheme-mode)
+ hilit-auto-highlight nil
+ hilit-auto-rehighlight 'visible
+ hilit-inhibit-hooks nil
+ hilit-inhibit-rebinding t)
+ (require 'hilit19)
+ (require 'paren))
+ (setq baud-rate 2400) ; For slow serial connections
+ )
+
+;; TTY type terminal
+(if (and (not window-system)
+ (not (equal system-type 'ms-dos)))
+ (progn
+ (if first-time
+ (progn
+ (keyboard-translate ?\C-h ?\C-?)
+ (keyboard-translate ?\C-? ?\C-h)))))
+
+;; Under UNIX
+(if (not (equal system-type 'ms-dos))
+ (progn
+ (if first-time
+ (server-start))))
+
+;; Add any face changes here
+(add-hook 'term-setup-hook 'my-term-setup-hook)
+(defun my-term-setup-hook ()
+ (if (eq window-system 'pc)
+ (progn
+;; (set-face-background 'default "red")
+ )))
+
+;; Restore the "desktop" - do this as late as possible
+(if first-time
+ (progn
+ (desktop-load-default)
+ (desktop-read)))
+
+;; Indicate that this file has been read at least once
+(setq first-time nil)
+
+;; No need to debug anything now
+(setq debug-on-error nil)
+
+;; All done
+(message "All done, %s%s" (user-login-name) ".")
+
+
+
+
+
+ Extending the Range of Languages Emacs Understands
+
+ Now, this is all very well if you only want to program in
+ the languages already catered for in the
+ .emacs file (C, C++, Perl, Lisp and
+ Scheme), but what happens if a new language called
+ whizbang comes out, full of exciting
+ features?
+
+ The first thing to do is find out if whizbang comes with
+ any files that tell Emacs about the language. These usually
+ end in .el, short for Emacs
+ Lisp. For example, if whizbang is a FreeBSD port, we
+ can locate these files by doing
+
+ &prompt.user; find /usr/ports/lang/whizbang -name "*.el" -print
+
+
+ and install them by copying them into the Emacs site Lisp
+ directory. On FreeBSD 2.1.0-RELEASE, this is
+ /usr/local/share/emacs/site-lisp.
+
+ So for example, if the output from the find command
+ was
+
+ /usr/ports/lang/whizbang/work/misc/whizbang.el
+
+
+ we would do
+
+ &prompt.root; cp /usr/ports/lang/whizbang/work/misc/whizbang.el /usr/local/share/emacs/site-lisp
+
+
+ Next, we need to decide what extension whizbang source
+ files have. Let's say for the sake of argument that they all
+ end in .wiz. We need to add an entry to
+ our .emacs file to make sure Emacs will
+ be able to use the information in
+ whizbang.el.
+
+ Find the auto-mode-alist entry in
+ .emacs and add a line for whizbang, such
+ as:
+
+ …
+("\\.lsp$" . lisp-mode)
+("\\.wiz$" . whizbang-mode)
+("\\.scm$" . scheme-mode)
+…
+
+
+ This means that Emacs will automatically go into
+ whizbang-mode when you edit a file ending
+ in .wiz.
+
+ Just below this, you'll find the
+ font-lock-auto-mode-list entry. Add
+ whizbang-mode to it like so:
+
+ ;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'whizbang-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+
+ This means that Emacs will always enable
+ font-lock-mode (ie syntax highlighting)
+ when editing a .wiz file.
+
+ And that's all that's needed. If there's anything else
+ you want done automatically when you open up a
+ .wiz file, you can add a
+ whizbang-mode hook (see
+ my-scheme-mode-hook for a simple example
+ that adds auto-indent).
+
+
+
+
+ Further Reading
+
+
+
+ Brian Harvey and Matthew Wright
+ Simply Scheme
+ MIT 1994.
+ ISBN 0-262-08226-8
+
+
+
+ Randall Schwartz
+ Learning Perl
+ O'Reilly 1993
+ ISBN 1-56592-042-2
+
+
+
+ Patrick Henry Winston and Berthold Klaus Paul Horn
+ Lisp (3rd Edition)
+ Addison-Wesley 1989
+ ISBN 0-201-08319-1
+
+
+
+ Brian W. Kernighan and Rob Pike
+ The Unix Programming Environment
+ Prentice-Hall 1984
+ ISBN 0-13-937681-X
+
+
+
+ Brian W. Kernighan and Dennis M. Ritchie
+ The C Programming Language (2nd Edition)
+ Prentice-Hall 1988
+ ISBN 0-13-110362-8
+
+
+
+ Bjarne Stroustrup
+ The C++ Programming Language
+ Addison-Wesley 1991
+ ISBN 0-201-53992-6
+
+
+
+ W. Richard Stevens
+ Advanced Programming in the Unix Environment
+ Addison-Wesley 1992
+ ISBN 0-201-56317-7
+
+
+
+ W. Richard Stevens
+ Unix Network Programming
+ Prentice-Hall 1990
+ ISBN 0-13-949876-1
+
+
+
-
@@ -1357,7 +3598,7 @@ DRIVER_MODULE(mypci, pci, mypci_driver, mypci_devclass, 0, 0);
-
+ Debugging
diff --git a/en_US.ISO8859-1/books/developers-handbook/book.sgml b/en_US.ISO8859-1/books/developers-handbook/book.sgml
index 8aacd1d42a..bd58d4a25a 100644
--- a/en_US.ISO8859-1/books/developers-handbook/book.sgml
+++ b/en_US.ISO8859-1/books/developers-handbook/book.sgml
@@ -1,7 +1,7 @@
Basics
-
- Compilation
+
+ Programming Tools
- This will include things like: compilation, makefiles, .mk
- files, basic debugging, linking, secure programming
- guidelines, style(9), CVS, diff, patch, etc.
+ This chapter was written by James Raynard.
+ Modifications for the Developer's Handbook by Murray Stokely.
+
+
+ Synopsis
+
+ This document is an introduction to using some of the
+ programming tools supplied with FreeBSD, although much of it
+ will be applicable to many other versions of Unix. It does
+ not attempt to describe coding in any
+ detail. Most of the document assumes little or no previous
+ programming knowledge, although it is hoped that most
+ programmers will find something of value in it
+
+
+
+ Introduction
+
+ FreeBSD offers an excellent development environment.
+ Compilers for C, C++, and Fortran and an assembler come with the
+ basic system, not to mention a Perl interpreter and classic Unix
+ tools such as sed and awk.
+ If that is not enough, there are many more compilers and
+ interpreters in the Ports collection. FreeBSD is very
+ compatible with standards such as POSIX and
+ ANSI C, as well with its own BSD heritage, so
+ it is possible to write applications that will compile and run
+ with little or no modification on a wide range of
+ platforms.
+
+ However, all this power can be rather overwhelming at
+ first if you've never written programs on a Unix platform
+ before. This document aims to help you get up and running,
+ without getting too deeply into more advanced topics. The
+ intention is that this document should give you enough of the
+ basics to be able to make some sense of the
+ documentation.
+
+ Most of the document requires little or no knowledge of
+ programming, although it does assume a basic competence with
+ using Unix and a willingness to learn!
+
+
+
+
+ Introduction to Programming
+
+ A program is a set of instructions that tell the computer
+ to do various things; sometimes the instruction it has to
+ perform depends on what happened when it performed a previous
+ instruction. This section gives an overview of the two main
+ ways in which you can give these instructions, or
+ commands as they are usually called. One way
+ uses an interpreter, the other a
+ compiler. As human languages are too
+ difficult for a computer to understand in an unambiguous way,
+ commands are usually written in one or other languages specially
+ designed for the purpose.
+
+
+ Interpreters
+
+ With an interpreter, the language comes as an environment,
+ where you type in commands at a prompt and the environment
+ executes them for you. For more complicated programs, you can
+ type the commands into a file and get the interpreter to load
+ the file and execute the commands in it. If anything goes
+ wrong, many interpreters will drop you into a debugger to help
+ you track down the problem.
+
+ The advantage of this is that you can see the results of
+ your commands immediately, and mistakes can be corrected
+ readily. The biggest disadvantage comes when you want to
+ share your programs with someone. They must have the same
+ interpreter, or you must have some way of giving it to them,
+ and they need to understand how to use it. Also users may not
+ appreciate being thrown into a debugger if they press the
+ wrong key! From a performance point of view, interpreters can
+ use up a lot of memory, and generally do not generate code as
+ efficiently as compilers.
+
+ In my opinion, interpreted languages are the best way to
+ start if you have not done any programming before. This kind
+ of environment is typically found with languages like Lisp,
+ Smalltalk, Perl and Basic. It could also be argued that the
+ Unix shell (sh, csh) is itself an
+ interpreter, and many people do in fact write shell
+ scripts to help with various
+ housekeeping tasks on their machine. Indeed, part
+ of the original Unix philosophy was to provide lots of small
+ utility programs that could be linked together in shell
+ scripts to perform useful tasks.
+
+
+
+ Interpreters available with FreeBSD
+
+ Here is a list of interpreters that are available as
+ FreeBSD
+ packages, with a brief discussion of some of the
+ more popular interpreted languages.
+
+ To get one of these packages, all you need to do is to
+ click on the hotlink for the package, then run
+
+ &prompt.root; pkg_add package name
+
+
+ as root. Obviously, you will need to have a fully
+ functional FreeBSD 2.1.0 or later system for the package to
+ work!
+
+
+
+ BASIC
+
+
+ Short for Beginner's All-purpose Symbolic
+ Instruction Code. Developed in the 1950s for teaching
+ University students to program and provided with every
+ self-respecting personal computer in the 1980s,
+ BASIC has been the first programming
+ language for many programmers. It's also the foundation
+ for Visual Basic.
+
+ The Bywater
+ Basic Interpreter and the Phil
+ Cockroft's Basic Interpreter (formerly Rabbit
+ Basic) are available as FreeBSD FreeBSD
+ packages
+
+
+
+
+ Lisp
+
+
+ A language that was developed in the late 1950s as
+ an alternative to the number-crunching
+ languages that were popular at the time. Instead of
+ being based on numbers, Lisp is based on lists; in fact
+ the name is short for List Processing.
+ Very popular in AI (Artificial Intelligence)
+ circles.
+
+ Lisp is an extremely powerful and sophisticated
+ language, but can be rather large and unwieldy.
+
+ FreeBSD has GNU
+ Common Lisp available as a package.
+
+
+
+
+ Perl
+
+
+ Very popular with system administrators for writing
+ scripts; also often used on World Wide Web servers for
+ writing CGI scripts.
+
+ The latest version (version 5) comes with FreeBSD.
+
+
+
+
+ Scheme
+
+
+ A dialect of Lisp that is rather more compact and
+ cleaner than Common Lisp. Popular in Universities as it
+ is simple enough to teach to undergraduates as a first
+ language, while it has a high enough level of
+ abstraction to be used in research work.
+
+ FreeBSD has packages of the Elk
+ Scheme Interpreter, the MIT
+ Scheme Interpreter and the SCM
+ Scheme Interpreter.
+
+
+
+
+ Icon
+
+
+ The
+ Icon Programming Language.
+
+
+
+
+ Logo
+
+
+ Brian
+ Harvey's LOGO Interpreter.
+
+
+
+
+ Python
+
+
+ The
+ Python Object-Oriented Programming
+ Language
+
+
+
+
+
+
+ Compilers
+
+ Compilers are rather different. First of all, you write
+ your code in a file (or files) using an editor. You then run
+ the compiler and see if it accepts your program. If it did
+ not compile, grit your teeth and go back to the editor; if it
+ did compile and gave you a program, you can run it either at a
+ shell command prompt or in a debugger to see if it works
+ properly.
+
+
+ If you run it in the shell, you may get a core
+ dump.
+
+
+ Obviously, this is not quite as direct as using an
+ interpreter. However it allows you to do a lot of things
+ which are very difficult or even impossible with an
+ interpreter, such as writing code which interacts closely with
+ the operating system—or even writing your own operating
+ system! It's also useful if you need to write very efficient
+ code, as the compiler can take its time and optimise the code,
+ which would not be acceptable in an interpreter. And
+ distributing a program written for a compiler is usually more
+ straightforward than one written for an interpreter—you
+ can just give them a copy of the executable, assuming they
+ have the same operating system as you.
+
+ Compiled languages include Pascal, C and C++. C and C++
+ are rather unforgiving languages, and best suited to more
+ experienced programmers; Pascal, on the other hand, was
+ designed as an educational language, and is quite a good
+ language to start with. Unfortunately, FreeBSD doesn't have
+ any Pascal support, except for a Pascal-to-C converter in the
+ ports.
+
+ As the edit-compile-run-debug cycle is rather tedious when
+ using separate programs, many commercial compiler makers have
+ produced Integrated Development Environments
+
+ (IDEs for short). FreeBSD does not have an
+ IDE as such; however it is possible to use Emacs
+ for this purpose. This is discussed in .
+
+
+
+
+
+
+
+ Compiling with <command>cc</command>
+
+ This section deals only with the GNU compiler for C and C++,
+ since that comes with the base FreeBSD system. It can be
+ invoked by either cc or gcc. The
+ details of producing a program with an interpreter vary
+ considerably between interpreters, and are usually well covered
+ in the documentation and on-line help for the
+ interpreter.
+
+ Once you've written your masterpiece, the next step is to
+ convert it into something that will (hopefully!) run on FreeBSD.
+ This usually involves several steps, each of which is done by a
+ separate program.
+
+
+
+ Pre-process your source code to remove comments and do
+ other tricks like expanding macros in C.
+
+
+
+ Check the syntax of your code to see if you have obeyed
+ the rules of the language. If you have not, it will
+ complain!
+
+
+
+ Convert the source code into assembly
+ language—this is very close to machine code, but still
+ understandable by humans. Allegedly.
+
+
+ To be strictly accurate, cc converts the
+ source code into its own, machine-independent
+ p-code instead of assembly language at
+ this stage.
+
+
+
+
+ Convert the assembly language into machine
+ code—yep, we are talking bits and bytes, ones and
+ zeros here.
+
+
+
+ Check that you have used things like functions and
+ global variables in a consistent way. For example, if you
+ have called a non-existent function, it will
+ complain.
+
+
+
+ If you are trying to produce an executable from several
+ source code files, work out how to fit them all
+ together.
+
+
+
+ Work out how to produce something that the system's
+ run-time loader will be able to load into memory and
+ run.
+
+
+
+ Finally, write the executable on the file system.
+
+
+
+ The word compiling is often used to refer to
+ just steps 1 to 4—the others are referred to as
+ linking. Sometimes step 1 is referred to as
+ pre-processing and steps 3-4 as
+ assembling.
+
+ Fortunately, almost all this detail is hidden from you, as
+ cc is a front end that manages calling all these
+ programs with the right arguments for you; simply typing
+
+ &prompt.user; cc foobar.c
+
+
+ will cause foobar.c to be compiled by all the
+ steps above. If you have more than one file to compile, just do
+ something like
+
+ &prompt.user; cc foo.c bar.c
+
+
+ Note that the syntax checking is just that—checking
+ the syntax. It will not check for any logical mistakes you may
+ have made, like putting the program into an infinite loop, or
+ using a bubble sort when you meant to use a binary
+ sort.
+
+
+ In case you didn't know, a binary sort is an efficient
+ way of sorting things into order and a bubble sort
+ isn't.
+
+
+ There are lots and lots of options for cc, which
+ are all in the man page. Here are a few of the most important
+ ones, with examples of how to use them.
+
+
+
+
+
+
+ The output name of the file. If you do not use this
+ option, cc will produce an executable called
+ a.out.
+
+
+ The reasons for this are buried in the mists of
+ history.
+
+
+
+ &prompt.user; cc foobar.c executable is a.out
+&prompt.user; cc -o foobar foobar.c executable is foobar
+
+
+
+
+
+
+
+
+
+ Just compile the file, do not link it. Useful for toy
+ programs where you just want to check the syntax, or if
+ you are using a Makefile.
+
+
+ &prompt.user; cc -c foobar.c
+
+
+
+ This will produce an object file (not an
+ executable) called foobar.o. This
+ can be linked together with other object files into an
+ executable.
+
+
+
+
+
+
+
+ Create a debug version of the executable. This makes
+ the compiler put information into the executable about
+ which line of which source file corresponds to which
+ function call. A debugger can use this information to show
+ the source code as you step through the program, which is
+ very useful; the disadvantage is that
+ all this extra information makes the program much bigger.
+ Normally, you compile with while you
+ are developing a program and then compile a release
+ version without when you're
+ satisfied it works properly.
+
+
+ &prompt.user; cc -g foobar.c
+
+
+
+ This will produce a debug version of the
+ program.
+
+
+ Note, we didn't use the flag
+ to specify the executable name, so we will get an
+ executable called a.out.
+ Producing a debug version called
+ foobar is left as an exercise for
+ the reader!
+
+
+
+
+
+
+
+
+ Create an optimised version of the executable. The
+ compiler performs various clever tricks to try and produce
+ an executable that runs faster than normal. You can add a
+ number after the to specify a higher
+ level of optimisation, but this often exposes bugs in the
+ compiler's optimiser. For instance, the version of
+ cc that comes with the 2.1.0 release of
+ FreeBSD is known to produce bad code with the
+ option in some circumstances.
+
+ Optimisation is usually only turned on when compiling
+ a release version.
+
+
+ &prompt.user; cc -O -o foobar foobar.c
+
+
+
+ This will produce an optimised version of
+ foobar.
+
+
+
+
+ The following three flags will force cc
+ to check that your code complies to the relevant international
+ standard, often referred to as the ANSI
+ standard, though strictly speaking it is an
+ ISO standard.
+
+
+
+
+
+
+ Enable all the warnings which the authors of
+ cc believe are worthwhile. Despite the
+ name, it will not enable all the warnings
+ cc is capable of.
+
+
+
+
+
+
+
+ Turn off most, but not all, of the
+ non-ANSI C features provided by
+ cc. Despite the name, it does not
+ guarantee strictly that your code will comply to the
+ standard.
+
+
+
+
+
+
+
+ Turn off all
+ cc's non-ANSI C
+ features.
+
+
+
+
+ Without these flags, cc will allow you to
+ use some of its non-standard extensions to the standard. Some
+ of these are very useful, but will not work with other
+ compilers—in fact, one of the main aims of the standard is
+ to allow people to write code that will work with any compiler
+ on any system. This is known as portable
+ code.
+
+ Generally, you should try to make your code as portable as
+ possible, as otherwise you may have to completely re-write the
+ program later to get it to work somewhere else—and who
+ knows what you may be using in a few years time?
+
+
+ &prompt.user; cc -Wall -ansi -pedantic -o foobar foobar.c
+
+
+
+ This will produce an executable foobar
+ after checking foobar.c for standard
+ compliance.
+
+
+
+
+
+
+ Specify a function library to be used during when
+ linking.
+
+ The most common example of this is when compiling a
+ program that uses some of the mathematical functions in C.
+ Unlike most other platforms, these are in a separate
+ library from the standard C one and you have to tell the
+ compiler to add it.
+
+ The rule is that if the library is called
+ libsomething.a,
+ you give cc the argument
+ .
+ For example, the math library is
+ libm.a, so you give
+ cc the argument .
+ A common gotcha with the math library is
+ that it has to be the last library on the command
+ line.
+
+
+ &prompt.user; cc -o foobar foobar.c -lm
+
+
+
+ This will link the math library functions into
+ foobar.
+
+ If you are compiling C++ code, you need to add
+ , or if
+ you are using FreeBSD 2.2 or later, to the command line
+ argument to link the C++ library functions.
+ Alternatively, you can run c++ instead
+ of cc, which does this for you.
+ c++ can also be invoked as
+ g++ on FreeBSD.
+
+
+ &prompt.user; cc -o foobar foobar.cc -lg++For FreeBSD 2.1.6 and earlier
+&prompt.user; cc -o foobar foobar.cc -lstdc++For FreeBSD 2.2 and later
+&prompt.user; c++ -o foobar foobar.cc
+
+
+
+ Each of these will both produce an executable
+ foobar from the C++ source file
+ foobar.cc. Note that, on Unix
+ systems, C++ source files traditionally end in
+ .C, .cxx or
+ .cc, rather than the
+ MS-DOS style
+ .cpp (which was already used for
+ something else). gcc used to rely on
+ this to work out what kind of compiler to use on the
+ source file; however, this restriction no longer applies,
+ so you may now call your C++ files
+ .cpp with impunity!
+
+
+
+
+
+ Common <command>cc</command> Queries and Problems
+
+
+
+
+ I am trying to write a program which uses the
+ sin() function and I get an error
+ like this. What does it mean?
+
+
+ /var/tmp/cc0143941.o: Undefined symbol `_sin' referenced from text segment
+
+
+
+
+
+ When using mathematical functions like
+ sin(), you have to tell
+ cc to link in the math library, like
+ so:
+
+
+ &prompt.user; cc -o foobar foobar.c -lm
+
+
+
+
+
+
+
+ All right, I wrote this simple program to practice
+ using . All it does is raise 2.1 to
+ the power of 6.
+
+
+ #include <stdio.h>
+
+int main() {
+ float f;
+
+ f = pow(2.1, 6);
+ printf("2.1 ^ 6 = %f\n", f);
+ return 0;
+}
+
+
+
+ and I compiled it as:
+
+
+ &prompt.user; cc temp.c -lm
+
+
+
+ like you said I should, but I get this when I run
+ it:
+
+
+ &prompt.user; ./a.out
+2.1 ^ 6 = 1023.000000
+
+
+
+ This is not the right answer!
+ What is going on?
+
+
+
+ When the compiler sees you call a function, it
+ checks if it has already seen a prototype for it. If it
+ has not, it assumes the function returns an
+ int, which is definitely not what you want
+ here.
+
+
+
+
+
+ So how do I fix this?
+
+
+
+ The prototypes for the mathematical functions are in
+ math.h. If you include this file,
+ the compiler will be able to find the prototype and it
+ will stop doing strange things to your
+ calculation!
+
+
+ #include <math.h>
+#include <stdio.h>
+
+int main() {
+...
+
+
+
+ After recompiling it as you did before, run
+ it:
+
+
+ &prompt.user; ./a.out
+2.1 ^ 6 = 85.766121
+
+
+
+ If you are using any of the mathematical functions,
+ always include
+ math.h and remember to link in the
+ math library.
+
+
+
+
+
+ I compiled a file called
+ foobar.c and I cannot find an
+ executable called foobar. Where's
+ it gone?
+
+
+
+ Remember, cc will call the
+ executable a.out unless you tell it
+ differently. Use the
+
+ option:
+
+
+ &prompt.user; cc -o foobar foobar.c
+
+
+
+
+
+
+
+ OK, I have an executable called
+ foobar, I can see it when I run
+ ls, but when I type in
+ foobar at the command prompt it tells
+ me there is no such file. Why can it not find
+ it?
+
+
+
+ Unlike MS-DOS, Unix does not
+ look in the current directory when it is trying to find
+ out which executable you want it to run, unless you tell
+ it to. Either type ./foobar, which
+ means run the file called
+ foobar in the current
+ directory, or change your PATH environment
+ variable so that it looks something like
+
+
+ bin:/usr/bin:/usr/local/bin:.
+
+
+
+ The dot at the end means look in the current
+ directory if it is not in any of the
+ others.
+
+
+
+
+
+ I called my executable test,
+ but nothing happens when I run it. What is going
+ on?
+
+
+
+ Most Unix systems have a program called
+ test in /usr/bin
+ and the shell is picking that one up before it gets to
+ checking the current directory. Either type:
+
+
+ &prompt.user; ./test
+
+
+
+ or choose a better name for your program!
+
+
+
+
+
+ I compiled my program and it seemed to run all right
+ at first, then there was an error and it said something
+ about core dumped. What does that
+ mean?
+
+
+
+ The name core dump dates back
+ to the very early days of Unix, when the machines used
+ core memory for storing data. Basically, if the program
+ failed under certain conditions, the system would write
+ the contents of core memory to disk in a file called
+ core, which the programmer could
+ then pore over to find out what went wrong.
+
+
+
+
+
+ Fascinating stuff, but what I am supposed to do
+ now?
+
+
+
+ Use gdb to analyse the core (see
+ ).
+
+
+
+
+
+ When my program dumped core, it said something about
+ a segmentation fault. What's
+ that?
+
+
+
+ This basically means that your program tried to
+ perform some sort of illegal operation on memory; Unix
+ is designed to protect the operating system and other
+ programs from rogue programs.
+
+ Common causes for this are:
+
+
+
+ Trying to write to a NULL
+ pointer, eg
+
+ char *foo = NULL;
+strcpy(foo, "bang!");
+
+
+
+
+ Using a pointer that hasn't been initialised,
+ eg
+
+ char *foo;
+strcpy(foo, "bang!");
+
+
+ The pointer will have some random value that,
+ with luck, will point into an area of memory that
+ isn't available to your program and the kernel will
+ kill your program before it can do any damage. If
+ you're unlucky, it'll point somewhere inside your
+ own program and corrupt one of your data structures,
+ causing the program to fail mysteriously.
+
+
+
+ Trying to access past the end of an array,
+ eg
+
+ int bar[20];
+bar[27] = 6;
+
+
+
+
+ Trying to store something in read-only memory,
+ eg
+
+ char *foo = "My string";
+strcpy(foo, "bang!");
+
+
+ Unix compilers often put string literals like
+ "My string" into read-only areas
+ of memory.
+
+
+
+ Doing naughty things with
+ malloc() and
+ free(), eg
+
+ char bar[80];
+free(bar);
+
+
+ or
+
+ char *foo = malloc(27);
+free(foo);
+free(foo);
+
+
+
+
+ Making one of these mistakes will not always lead to
+ an error, but they are always bad practice. Some
+ systems and compilers are more tolerant than others,
+ which is why programs that ran well on one system can
+ crash when you try them on an another.
+
+
+
+
+
+ Sometimes when I get a core dump it says
+ bus error. It says in my Unix
+ book that this means a hardware problem, but the
+ computer still seems to be working. Is this
+ true?
+
+
+
+ No, fortunately not (unless of course you really do
+ have a hardware problem…). This is usually
+ another way of saying that you accessed memory in a way
+ you shouldn't have.
+
+
+
+
+
+ This dumping core business sounds as though it could
+ be quite useful, if I can make it happen when I want to.
+ Can I do this, or do I have to wait until there's an
+ error?
+
+
+
+ Yes, just go to another console or xterm, do
+
+ &prompt.user; ps
+
+
+ to find out the process ID of your program, and
+ do
+
+ &prompt.user; kill -ABRT pid
+
+
+ where
+ pid is
+ the process ID you looked up.
+
+ This is useful if your program has got stuck in an
+ infinite loop, for instance. If your program happens to
+ trap SIGABRT, there are several other
+ signals which have a similar effect.
+
+
+
+
+
+
+
+ Make
+
+
+ What is <command>make</command>?
+
+ When you're working on a simple program with only one or
+ two source files, typing in
+
+ &prompt.user; cc file1.c file2.c
+
+
+ is not too bad, but it quickly becomes very tedious when
+ there are several files—and it can take a while to
+ compile, too.
+
+ One way to get around this is to use object files and only
+ recompile the source file if the source code has changed. So
+ we could have something like:
+
+ &prompt.user; cc file1.o file2.o … file37.c &hellip
+
+
+ if we'd changed file37.c, but not any
+ of the others, since the last time we compiled. This may
+ speed up the compilation quite a bit, but doesn't solve the
+ typing problem.
+
+ Or we could write a shell script to solve the typing
+ problem, but it would have to re-compile everything, making it
+ very inefficient on a large project.
+
+ What happens if we have hundreds of source files lying
+ about? What if we're working in a team with other people who
+ forget to tell us when they've changed one of their source
+ files that we use?
+
+ Perhaps we could put the two solutions together and write
+ something like a shell script that would contain some kind of
+ magic rule saying when a source file needs compiling. Now all
+ we need now is a program that can understand these rules, as
+ it's a bit too complicated for the shell.
+
+ This program is called make. It reads
+ in a file, called a makefile, that
+ tells it how different files depend on each other, and works
+ out which files need to be re-compiled and which ones don't.
+ For example, a rule could say something like if
+ fromboz.o is older than
+ fromboz.c, that means someone must have
+ changed fromboz.c, so it needs to be
+ re-compiled. The makefile also has rules telling
+ make how to re-compile the source file,
+ making it a much more powerful tool.
+
+ Makefiles are typically kept in the same directory as the
+ source they apply to, and can be called
+ makefile, Makefile
+ or MAKEFILE. Most programmers use the
+ name Makefile, as this puts it near the
+ top of a directory listing, where it can easily be
+ seen.
+
+
+ They don't use the MAKEFILE form
+ as block capitals are often used for documentation files
+ like README.
+
+
+
+
+ Example of using <command>make</command>
+
+ Here's a very simple make file:
+
+ foo: foo.c
+ cc -o foo foo.c
+
+
+ It consists of two lines, a dependency line and a creation
+ line.
+
+ The dependency line here consists of the name of the
+ program (known as the target), followed
+ by a colon, then whitespace, then the name of the source file.
+ When make reads this line, it looks to see
+ if foo exists; if it exists, it compares
+ the time foo was last modified to the
+ time foo.c was last modified. If
+ foo does not exist, or is older than
+ foo.c, it then looks at the creation line
+ to find out what to do. In other words, this is the rule for
+ working out when foo.c needs to be
+ re-compiled.
+
+ The creation line starts with a tab (press
+ the tab key) and then the command you would
+ type to create foo if you were doing it
+ at a command prompt. If foo is out of
+ date, or does not exist, make then executes
+ this command to create it. In other words, this is the rule
+ which tells make how to re-compile
+ foo.c.
+
+ So, when you type make, it will
+ make sure that foo is up to date with
+ respect to your latest changes to foo.c.
+ This principle can be extended to
+ Makefiles with hundreds of
+ targets—in fact, on FreeBSD, it is possible to compile
+ the entire operating system just by typing make
+ world in the appropriate directory!
+
+ Another useful property of makefiles is that the targets
+ don't have to be programs. For instance, we could have a make
+ file that looks like this:
+
+ foo: foo.c
+ cc -o foo foo.c
+
+install:
+ cp foo /home/me
+
+
+ We can tell make which target we want to make by
+ typing:
+
+ &prompt.user; make target
+
+
+ make will then only look at that target
+ and ignore any others. For example, if we type
+ make foo with the makefile above, make
+ will ignore the install target.
+
+ If we just type make on its own,
+ make will always look at the first target and then stop
+ without looking at any others. So if we typed
+ make here, it will just go to the
+ foo target, re-compile
+ foo if necessary, and then stop without
+ going on to the install target.
+
+ Notice that the install target doesn't
+ actually depend on anything! This means that the command on
+ the following line is always executed when we try to make that
+ target by typing make install. In this
+ case, it will copy foo into the user's
+ home directory. This is often used by application makefiles,
+ so that the application can be installed in the correct
+ directory when it has been correctly compiled.
+
+ This is a slightly confusing subject to try and explain.
+ If you don't quite understand how make
+ works, the best thing to do is to write a simple program like
+ hello world and a make file like the one above
+ and experiment. Then progress to using more than one source
+ file, or having the source file include a header file. The
+ touch command is very useful here—it
+ changes the date on a file without you having to edit
+ it.
+
+
+
+ FreeBSD Makefiles
+
+ Makefiles can be rather complicated to write. Fortunately,
+ BSD-based systems like FreeBSD come with some very powerful
+ ones as part of the system. One very good example of this is
+ the FreeBSD ports system. Here's the essential part of a
+ typical ports Makefile:
+
+ MASTER_SITES= ftp://freefall.cdrom.com/pub/FreeBSD/LOCAL_PORTS/
+DISTFILES= scheme-microcode+dist-7.3-freebsd.tgz
+
+.include <bsd.port.mk>
+
+
+ Now, if we go to the directory for this port and type
+ make, the following happens:
+
+
+
+ A check is made to see if the source code for this
+ port is already on the system.
+
+
+
+ If it isn't, an FTP connection to the URL in
+ MASTER_SITES is set up to download the
+ source.
+
+
+
+ The checksum for the source is calculated and compared
+ it with one for a known, good, copy of the source. This
+ is to make sure that the source was not corrupted while in
+ transit.
+
+
+
+ Any changes required to make the source work on
+ FreeBSD are applied—this is known as
+ patching.
+
+
+
+ Any special configuration needed for the source is
+ done. (Many Unix program distributions try to work out
+ which version of Unix they are being compiled on and which
+ optional Unix features are present—this is where
+ they are given the information in the FreeBSD ports
+ scenario).
+
+
+
+ The source code for the program is compiled. In
+ effect, we change to the directory where the source was
+ unpacked and do make—the
+ program's own make file has the necessary information to
+ build the program.
+
+
+
+ We now have a compiled version of the program. If we
+ wish, we can test it now; when we feel confident about the
+ program, we can type make install.
+ This will cause the program and any supporting files it
+ needs to be copied into the correct location; an entry is
+ also made into a package database, so
+ that the port can easily be uninstalled later if we change
+ our mind about it.
+
+
+
+ Now I think you'll agree that's rather impressive for a
+ four line script!
+
+ The secret lies in the last line, which tells
+ make to look in the system makefile called
+ bsd.port.mk. It's easy to overlook this
+ line, but this is where all the clever stuff comes
+ from—someone has written a makefile that tells
+ make to do all the things above (plus a
+ couple of other things I didn't mention, including handling
+ any errors that may occur) and anyone can get access to that
+ just by putting a single line in their own make file!
+
+ If you want to have a look at these system makefiles,
+ they're in /usr/share/mk, but it's
+ probably best to wait until you've had a bit of practice with
+ makefiles, as they are very complicated (and if you do look at
+ them, make sure you have a flask of strong coffee
+ handy!)
+
+
+
+ More advanced uses of <command>make</command>
+
+ Make is a very powerful tool, and can
+ do much more than the simple example above shows.
+ Unfortunately, there are several different versions of
+ make, and they all differ considerably.
+ The best way to learn what they can do is probably to read the
+ documentation—hopefully this introduction will have
+ given you a base from which you can do this.
+
+ The version of make that comes with FreeBSD is the
+ Berkeley make; there is a tutorial
+ for it in /usr/share/doc/psd/12.make. To
+ view it, do
+
+ &prompt.user; zmore paper.ascii.gz
+
+
+ in that directory.
+
+ Many applications in the ports use GNU
+ make, which has a very good set of
+ info pages. If you have installed any of these
+ ports, GNU make will automatically
+ have been installed as gmake. It's also
+ available as a port and package in its own right.
+
+ To view the info pages for GNU
+ make, you will have to edit the
+ dir file in the
+ /usr/local/info directory to add an entry
+ for it. This involves adding a line like
+
+ * Make: (make). The GNU Make utility.
+
+
+ to the file. Once you have done this, you can type
+ info and then select
+ make from the menu (or in
+ Emacs, do C-h
+ i).
+
+
+
+
+ Debugging
+
+
+ The Debugger
+
+ The debugger that comes with FreeBSD is called
+ gdb (GNU
+ debugger). You start it up by typing
+
+ &prompt.user; gdb progname
+
+
+ although most people prefer to run it inside
+ Emacs. You can do this by:
+
+ M-x gdb RET progname RET
+
+
+ Using a debugger allows you to run the program under more
+ controlled circumstances. Typically, you can step through the
+ program a line at a time, inspect the value of variables,
+ change them, tell the debugger to run up to a certain point
+ and then stop, and so on. You can even attach to a program
+ that's already running, or load a core file to investigate why
+ the program crashed. It's even possible to debug the kernel,
+ though that's a little trickier than the user applications
+ we'll be discussing in this section.
+
+ gdb has quite good on-line help, as
+ well as a set of info pages, so this section will concentrate
+ on a few of the basic commands.
+
+ Finally, if you find its text-based command-prompt style
+ off-putting, there's a graphical front-end for it xxgdb in the ports
+ collection.
+
+ This section is intended to be an introduction to using
+ gdb and does not cover specialised topics
+ such as debugging the kernel.
+
+
+
+ Running a program in the debugger
+
+ You'll need to have compiled the program with the
+ option to get the most out of using
+ gdb. It will work without, but you'll only
+ see the name of the function you're in, instead of the source
+ code. If you see a line like:
+
+ … (no debugging symbols found) …
+
+
+ when gdb starts up, you'll know that
+ the program wasn't compiled with the
+ option.
+
+ At the gdb prompt, type
+ break main. This will tell the
+ debugger to skip over the preliminary set-up code in the
+ program and start at the beginning of your code. Now type
+ run to start the program—it will
+ start at the beginning of the set-up code and then get stopped
+ by the debugger when it calls main().
+ (If you've ever wondered where main()
+ gets called from, now you know!).
+
+ You can now step through the program, a line at a time, by
+ pressing n. If you get to a function call,
+ you can step into it by pressing s. Once
+ you're in a function call, you can return from stepping into a
+ function call by pressing f. You can also
+ use up and down to take
+ a quick look at the caller.
+
+ Here's a simple example of how to spot a mistake in a
+ program with gdb. This is our program
+ (with a deliberate mistake):
+
+ #include <stdio.h>
+
+int bazz(int anint);
+
+main() {
+ int i;
+
+ printf("This is my program\n");
+ bazz(i);
+ return 0;
+}
+
+int bazz(int anint) {
+ printf("You gave me %d\n", anint);
+ return anint;
+}
+
+
+ This program sets i to be
+ 5 and passes it to a function
+ bazz() which prints out the number we
+ gave it.
+
+ When we compile and run the program we get
+
+ &prompt.user; cc -g -o temp temp.c
+&prompt.user; ./temp
+This is my program
+anint = 4231
+
+
+ That wasn't what we expected! Time to see what's going
+ on!
+
+ &prompt.user; gdb temp
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) break main Skip the set-up code
+Breakpoint 1 at 0x160f: file temp.c, line 9. gdb puts breakpoint at main()
+(gdb) run Run as far as main()
+Starting program: /home/james/tmp/temp Program starts running
+
+Breakpoint 1, main () at temp.c:9 gdb stops at main()
+(gdb) n Go to next line
+This is my program Program prints out
+(gdb) s step into bazz()
+bazz (anint=4231) at temp.c:17 gdb displays stack frame
+(gdb)
+
+
+ Hang on a minute! How did anint get to be
+ 4231? Didn't we set it to be
+ 5 in main()? Let's
+ move up to main() and have a look.
+
+ (gdb) up Move up call stack
+#1 0x1625 in main () at temp.c:11 gdb displays stack frame
+(gdb) p i Show us the value of i
+$1 = 4231 gdb displays 4231
+
+
+ Oh dear! Looking at the code, we forgot to initialise
+ i. We meant to put
+
+ …
+main() {
+ int i;
+
+ i = 5;
+ printf("This is my program\n");
+&hellip
+
+
+ but we left the i=5; line out. As we
+ didn't initialise i, it had whatever number
+ happened to be in that area of memory when the program ran,
+ which in this case happened to be
+ 4231.
+
+
+ gdb displays the stack frame every
+ time we go into or out of a function, even if we're using
+ up and down to move
+ around the call stack. This shows the name of the function
+ and the values of its arguments, which helps us keep track
+ of where we are and what's going on. (The stack is a
+ storage area where the program stores information about the
+ arguments passed to functions and where to go when it
+ returns from a function call).
+
+
+
+
+ Examining a core file
+
+ A core file is basically a file which contains the
+ complete state of the process when it crashed. In the
+ good old days, programmers had to print out hex
+ listings of core files and sweat over machine code manuals,
+ but now life is a bit easier. Incidentally, under FreeBSD and
+ other 4.4BSD systems, a core file is called
+ progname.core instead of just
+ core, to make it clearer which program a
+ core file belongs to.
+
+ To examine a core file, start up gdb in
+ the usual way. Instead of typing break or
+ run, type
+
+ (gdb) core progname.core
+
+
+ If you're not in the same directory as the core file,
+ you'll have to do dir
+ /path/to/core/file first.
+
+ You should see something like this:
+
+ &prompt.user; gdb a.out
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) core a.out.core
+Core was generated by `a.out'.
+Program terminated with signal 11, Segmentation fault.
+Cannot access memory at address 0x7020796d.
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+(gdb)
+
+
+ In this case, the program was called
+ a.out, so the core file is called
+ a.out.core. We can see that the program
+ crashed due to trying to access an area in memory that was not
+ available to it in a function called
+ bazz.
+
+ Sometimes it's useful to be able to see how a function was
+ called, as the problem could have occurred a long way up the
+ call stack in a complex program. The bt
+ command causes gdb to print out a
+ back-trace of the call stack:
+
+ (gdb) bt
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+#1 0xefbfd888 in end ()
+#2 0x162c in main () at temp.c:11
+(gdb)
+
+
+ The end() function is called when a
+ program crashes; in this case, the bazz()
+ function was called from main().
+
+
+
+ Attaching to a running program
+
+ One of the neatest features about gdb
+ is that it can attach to a program that's already running. Of
+ course, that assumes you have sufficient permissions to do so.
+ A common problem is when you are stepping through a program
+ that forks, and you want to trace the child, but the debugger
+ will only let you trace the parent.
+
+ What you do is start up another gdb,
+ use ps to find the process ID for the
+ child, and do
+
+ (gdb) attach pid
+
+
+ in gdb, and then debug as usual.
+
+ That's all very well, you're probably
+ thinking, but by the time I've done that, the child
+ process will be over the hill and far away. Fear
+ not, gentle reader, here's how to do it (courtesy of the
+ gdb info pages):
+
+ &hellip
+if ((pid = fork()) < 0) /* _Always_ check this */
+ error();
+else if (pid == 0) { /* child */
+ int PauseMode = 1;
+
+ while (PauseMode)
+ sleep(10); /* Wait until someone attaches to us */
+ &hellip
+} else { /* parent */
+ &hellip
+
+
+ Now all you have to do is attach to the child, set
+ PauseMode to 0, and wait
+ for the sleep() call to return!
+
+
+
+
+ Using Emacs as a Development Environment
+
+
+ Emacs
+
+ Unfortunately, Unix systems don't come with the kind of
+ everything-you-ever-wanted-and-lots-more-you-didn't-in-one-gigantic-package
+ integrated development environments that other systems
+ have.
+
+
+ At least, not unless you pay out very large sums of
+ money.
+
+
+ However, it is possible to set up your own environment. It
+ may not be as pretty, and it may not be quite as integrated,
+ but you can set it up the way you want it. And it's free.
+ And you have the source to it.
+
+ The key to it all is Emacs. Now there are some people who
+ loathe it, but many who love it. If you're one of the former,
+ I'm afraid this section will hold little of interest to you.
+ Also, you'll need a fair amount of memory to run it—I'd
+ recommend 8MB in text mode and 16MB in X as the bare minimum
+ to get reasonable performance.
+
+ Emacs is basically a highly customisable
+ editor—indeed, it has been customised to the point where
+ it's more like an operating system than an editor! Many
+ developers and sysadmins do in fact spend practically all
+ their time working inside Emacs, leaving it only to log
+ out.
+
+ It's impossible even to summarise everything Emacs can do
+ here, but here are some of the features of interest to
+ developers:
+
+
+
+ Very powerful editor, allowing search-and-replace on
+ both strings and regular expressions (patterns), jumping
+ to start/end of block expression, etc, etc.
+
+
+
+ Pull-down menus and online help.
+
+
+
+ Language-dependent syntax highlighting and
+ indentation.
+
+
+
+ Completely customisable.
+
+
+
+ You can compile and debug programs within
+ Emacs.
+
+
+
+ On a compilation error, you can jump to the offending
+ line of source code.
+
+
+
+ Friendly-ish front-end to the info
+ program used for reading GNU hypertext documentation,
+ including the documentation on Emacs itself.
+
+
+
+ Friendly front-end to gdb, allowing
+ you to look at the source code as you step through your
+ program.
+
+
+
+ You can read Usenet news and mail while your program
+ is compiling.
+
+
+
+ And doubtless many more that I've overlooked.
+
+ Emacs can be installed on FreeBSD using the Emacs
+ port.
+
+ Once it's installed, start it up and do C-h
+ t to read an Emacs tutorial—that means
+ hold down the control key, press
+ h, let go of the control
+ key, and then press t. (Alternatively, you
+ can you use the mouse to select Emacs
+ Tutorial from the Help
+ menu).
+
+ Although Emacs does have menus, it's well worth learning
+ the key bindings, as it's much quicker when you're editing
+ something to press a couple of keys than to try and find the
+ mouse and then click on the right place. And, when you're
+ talking to seasoned Emacs users, you'll find they often
+ casually throw around expressions like M-x
+ replace-s RET foo RET bar RET so it's
+ useful to know what they mean. And in any case, Emacs has far
+ too many useful functions for them to all fit on the menu
+ bars.
+
+ Fortunately, it's quite easy to pick up the key-bindings,
+ as they're displayed next to the menu item. My advice is to
+ use the menu item for, say, opening a file until you
+ understand how it works and feel confident with it, then try
+ doing C-x C-f. When you're happy with that, move on to
+ another menu command.
+
+ If you can't remember what a particular combination of
+ keys does, select Describe Key from
+ the Help menu and type it in—Emacs
+ will tell you what it does. You can also use the
+ Command Apropos menu item to find
+ out all the commands which contain a particular word in them,
+ with the key binding next to it.
+
+ By the way, the expression above means hold down the
+ Meta key, press x, release
+ the Meta key, type
+ replace-s (short for
+ replace-string—another feature of
+ Emacs is that you can abbreviate commands), press the
+ return key, type foo
+ (the string you want replaced), press the
+ return key, type bar (the string you want to
+ replace foo with) and press
+ return again. Emacs will then do the
+ search-and-replace operation you've just requested.
+
+ If you're wondering what on earth the
+ Meta key is, it's a special key that many
+ Unix workstations have. Unfortunately, PC's don't have one,
+ so it's usually the alt key (or if you're
+ unlucky, the escape key).
+
+ Oh, and to get out of Emacs, do C-x C-c
+ (that means hold down the control key, press
+ x, press c and release the
+ control key). If you have any unsaved files
+ open, Emacs will ask you if you want to save them. (Ignore
+ the bit in the documentation where it says
+ C-z is the usual way to leave
+ Emacs—that leaves Emacs hanging around in the
+ background, and is only really useful if you're on a system
+ which doesn't have virtual terminals).
+
+
+
+ Configuring Emacs
+
+ Emacs does many wonderful things; some of them are built
+ in, some of them need to be configured.
+
+ Instead of using a proprietary macro language for
+ configuration, Emacs uses a version of Lisp specially adapted
+ for editors, known as Emacs Lisp. This can be quite useful if
+ you want to go on and learn something like Common Lisp, as
+ it's considerably smaller than Common Lisp (although still
+ quite big!).
+
+ The best way to learn Emacs Lisp is to download the Emacs
+ Tutorial
+
+ However, there's no need to actually know any Lisp to get
+ started with configuring Emacs, as I've included a sample
+ .emacs file, which should be enough to
+ get you started. Just copy it into your home directory and
+ restart Emacs if it's already running; it will read the
+ commands from the file and (hopefully) give you a useful basic
+ setup.
+
+
+
+ A sample <filename>.emacs</filename> file
+
+ Unfortunately, there's far too much here to explain it in
+ detail; however there are one or two points worth
+ mentioning.
+
+
+
+ Everything beginning with a ; is a comment
+ and is ignored by Emacs.
+
+
+
+ In the first line, the
+ -*- Emacs-Lisp -*- is so that
+ we can edit the .emacs file itself
+ within Emacs and get all the fancy features for editing
+ Emacs Lisp. Emacs usually tries to guess this based on
+ the filename, and may not get it right for
+ .emacs.
+
+
+
+ The tab key is bound to an
+ indentation function in some modes, so when you press the
+ tab key, it will indent the current line of code. If you
+ want to put a tab character in whatever
+ you're writing, hold the control key down
+ while you're pressing the tab key.
+
+
+
+ This file supports syntax highlighting for C, C++,
+ Perl, Lisp and Scheme, by guessing the language from the
+ filename.
+
+
+
+ Emacs already has a pre-defined function called
+ next-error. In a compilation output
+ window, this allows you to move from one compilation error
+ to the next by doing M-n; we define a
+ complementary function,
+ previous-error, that allows you to go
+ to a previous error by doing M-p. The
+ nicest feature of all is that C-c C-c
+ will open up the source file in which the error occurred
+ and jump to the appropriate line.
+
+
+
+ We enable Emacs's ability to act as a server, so that
+ if you're doing something outside Emacs and you want to
+ edit a file, you can just type in
+
+ &prompt.user; emacsclient filename
+
+
+ and then you can edit the file in your
+ Emacs!
+
+
+ Many Emacs users set their EDITOR environment to
+ emacsclient so this happens every
+ time they need to edit a file.
+
+
+
+
+
+ A sample <filename>.emacs</filename> file
+
+ ;; -*-Emacs-Lisp-*-
+
+;; This file is designed to be re-evaled; use the variable first-time
+;; to avoid any problems with this.
+(defvar first-time t
+ "Flag signifying this is the first time that .emacs has been evaled")
+
+;; Meta
+(global-set-key "\M- " 'set-mark-command)
+(global-set-key "\M-\C-h" 'backward-kill-word)
+(global-set-key "\M-\C-r" 'query-replace)
+(global-set-key "\M-r" 'replace-string)
+(global-set-key "\M-g" 'goto-line)
+(global-set-key "\M-h" 'help-command)
+
+;; Function keys
+(global-set-key [f1] 'manual-entry)
+(global-set-key [f2] 'info)
+(global-set-key [f3] 'repeat-complex-command)
+(global-set-key [f4] 'advertised-undo)
+(global-set-key [f5] 'eval-current-buffer)
+(global-set-key [f6] 'buffer-menu)
+(global-set-key [f7] 'other-window)
+(global-set-key [f8] 'find-file)
+(global-set-key [f9] 'save-buffer)
+(global-set-key [f10] 'next-error)
+(global-set-key [f11] 'compile)
+(global-set-key [f12] 'grep)
+(global-set-key [C-f1] 'compile)
+(global-set-key [C-f2] 'grep)
+(global-set-key [C-f3] 'next-error)
+(global-set-key [C-f4] 'previous-error)
+(global-set-key [C-f5] 'display-faces)
+(global-set-key [C-f8] 'dired)
+(global-set-key [C-f10] 'kill-compilation)
+
+;; Keypad bindings
+(global-set-key [up] "\C-p")
+(global-set-key [down] "\C-n")
+(global-set-key [left] "\C-b")
+(global-set-key [right] "\C-f")
+(global-set-key [home] "\C-a")
+(global-set-key [end] "\C-e")
+(global-set-key [prior] "\M-v")
+(global-set-key [next] "\C-v")
+(global-set-key [C-up] "\M-\C-b")
+(global-set-key [C-down] "\M-\C-f")
+(global-set-key [C-left] "\M-b")
+(global-set-key [C-right] "\M-f")
+(global-set-key [C-home] "\M-<")
+(global-set-key [C-end] "\M->")
+(global-set-key [C-prior] "\M-<")
+(global-set-key [C-next] "\M->")
+
+;; Mouse
+(global-set-key [mouse-3] 'imenu)
+
+;; Misc
+(global-set-key [C-tab] "\C-q\t") ; Control tab quotes a tab.
+(setq backup-by-copying-when-mismatch t)
+
+;; Treat 'y' or <CR> as yes, 'n' as no.
+(fset 'yes-or-no-p 'y-or-n-p)
+ (define-key query-replace-map [return] 'act)
+ (define-key query-replace-map [?\C-m] 'act)
+
+;; Load packages
+(require 'desktop)
+(require 'tar-mode)
+
+;; Pretty diff mode
+(autoload 'ediff-buffers "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files-remote "ediff"
+ "Intelligent Emacs interface to diff")
+
+(if first-time
+ (setq auto-mode-alist
+ (append '(("\\.cpp$" . c++-mode)
+ ("\\.hpp$" . c++-mode)
+ ("\\.lsp$" . lisp-mode)
+ ("\\.scm$" . scheme-mode)
+ ("\\.pl$" . perl-mode)
+ ) auto-mode-alist)))
+
+;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+(defvar font-lock-mode-keyword-alist
+ '((c++-c-mode . c-font-lock-keywords)
+ (perl-mode . perl-font-lock-keywords))
+ "Associations between modes and keywords")
+
+(defun font-lock-auto-mode-select ()
+ "Automatically select font-lock-mode if the current major mode is
+in font-lock-auto-mode-list"
+ (if (memq major-mode font-lock-auto-mode-list)
+ (progn
+ (font-lock-mode t))
+ )
+ )
+
+(global-set-key [M-f1] 'font-lock-fontify-buffer)
+
+;; New dabbrev stuff
+;(require 'new-dabbrev)
+(setq dabbrev-always-check-other-buffers t)
+(setq dabbrev-abbrev-char-regexp "\\sw\\|\\s_")
+(add-hook 'emacs-lisp-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'c-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'text-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) t)
+ (set (make-local-variable 'dabbrev-case-replace) t)))
+
+;; C++ and C mode...
+(defun my-c++-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c++-mode-map "\C-ce" 'c-comment-edit)
+ (setq c++-auto-hungry-initial-state 'none)
+ (setq c++-delete-function 'backward-delete-char)
+ (setq c++-tab-always-indent t)
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c++-empty-arglist-indent 4))
+
+(defun my-c-mode-hook ()
+ (setq tab-width 4)
+ (define-key c-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c-mode-map "\C-ce" 'c-comment-edit)
+ (setq c-auto-hungry-initial-state 'none)
+ (setq c-delete-function 'backward-delete-char)
+ (setq c-tab-always-indent t)
+;; BSD-ish indentation style
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c-brace-offset -4)
+ (setq c-argdecl-indent 0)
+ (setq c-label-offset -4))
+
+;; Perl mode
+(defun my-perl-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (setq perl-indent-level 4)
+ (setq perl-continued-statement-offset 4))
+
+;; Scheme mode...
+(defun my-scheme-mode-hook ()
+ (define-key scheme-mode-map "\C-m" 'reindent-then-newline-and-indent))
+
+;; Emacs-Lisp mode...
+(defun my-lisp-mode-hook ()
+ (define-key lisp-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key lisp-mode-map "\C-i" 'lisp-indent-line)
+ (define-key lisp-mode-map "\C-j" 'eval-print-last-sexp))
+
+;; Add all of the hooks...
+(add-hook 'c++-mode-hook 'my-c++-mode-hook)
+(add-hook 'c-mode-hook 'my-c-mode-hook)
+(add-hook 'scheme-mode-hook 'my-scheme-mode-hook)
+(add-hook 'emacs-lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'perl-mode-hook 'my-perl-mode-hook)
+
+;; Complement to next-error
+(defun previous-error (n)
+ "Visit previous compilation error message and corresponding source code."
+ (interactive "p")
+ (next-error (- n)))
+
+;; Misc...
+(transient-mark-mode 1)
+(setq mark-even-if-inactive t)
+(setq visible-bell nil)
+(setq next-line-add-newlines nil)
+(setq compile-command "make")
+(setq suggest-key-bindings nil)
+(put 'eval-expression 'disabled nil)
+(put 'narrow-to-region 'disabled nil)
+(put 'set-goal-column 'disabled nil)
+
+;; Elisp archive searching
+(autoload 'format-lisp-code-directory "lispdir" nil t)
+(autoload 'lisp-dir-apropos "lispdir" nil t)
+(autoload 'lisp-dir-retrieve "lispdir" nil t)
+(autoload 'lisp-dir-verify "lispdir" nil t)
+
+;; Font lock mode
+(defun my-make-face (face colour &optional bold)
+ "Create a face from a colour and optionally make it bold"
+ (make-face face)
+ (copy-face 'default face)
+ (set-face-foreground face colour)
+ (if bold (make-face-bold face))
+ )
+
+(if (eq window-system 'x)
+ (progn
+ (my-make-face 'blue "blue")
+ (my-make-face 'red "red")
+ (my-make-face 'green "dark green")
+ (setq font-lock-comment-face 'blue)
+ (setq font-lock-string-face 'bold)
+ (setq font-lock-type-face 'bold)
+ (setq font-lock-keyword-face 'bold)
+ (setq font-lock-function-name-face 'red)
+ (setq font-lock-doc-string-face 'green)
+ (add-hook 'find-file-hooks 'font-lock-auto-mode-select)
+
+ (setq baud-rate 1000000)
+ (global-set-key "\C-cmm" 'menu-bar-mode)
+ (global-set-key "\C-cms" 'scroll-bar-mode)
+ (global-set-key [backspace] 'backward-delete-char)
+ ; (global-set-key [delete] 'delete-char)
+ (standard-display-european t)
+ (load-library "iso-transl")))
+
+;; X11 or PC using direct screen writes
+(if window-system
+ (progn
+ ;; (global-set-key [M-f1] 'hilit-repaint-command)
+ ;; (global-set-key [M-f2] [?\C-u M-f1])
+ (setq hilit-mode-enable-list
+ '(not text-mode c-mode c++-mode emacs-lisp-mode lisp-mode
+ scheme-mode)
+ hilit-auto-highlight nil
+ hilit-auto-rehighlight 'visible
+ hilit-inhibit-hooks nil
+ hilit-inhibit-rebinding t)
+ (require 'hilit19)
+ (require 'paren))
+ (setq baud-rate 2400) ; For slow serial connections
+ )
+
+;; TTY type terminal
+(if (and (not window-system)
+ (not (equal system-type 'ms-dos)))
+ (progn
+ (if first-time
+ (progn
+ (keyboard-translate ?\C-h ?\C-?)
+ (keyboard-translate ?\C-? ?\C-h)))))
+
+;; Under UNIX
+(if (not (equal system-type 'ms-dos))
+ (progn
+ (if first-time
+ (server-start))))
+
+;; Add any face changes here
+(add-hook 'term-setup-hook 'my-term-setup-hook)
+(defun my-term-setup-hook ()
+ (if (eq window-system 'pc)
+ (progn
+;; (set-face-background 'default "red")
+ )))
+
+;; Restore the "desktop" - do this as late as possible
+(if first-time
+ (progn
+ (desktop-load-default)
+ (desktop-read)))
+
+;; Indicate that this file has been read at least once
+(setq first-time nil)
+
+;; No need to debug anything now
+(setq debug-on-error nil)
+
+;; All done
+(message "All done, %s%s" (user-login-name) ".")
+
+
+
+
+
+ Extending the Range of Languages Emacs Understands
+
+ Now, this is all very well if you only want to program in
+ the languages already catered for in the
+ .emacs file (C, C++, Perl, Lisp and
+ Scheme), but what happens if a new language called
+ whizbang comes out, full of exciting
+ features?
+
+ The first thing to do is find out if whizbang comes with
+ any files that tell Emacs about the language. These usually
+ end in .el, short for Emacs
+ Lisp. For example, if whizbang is a FreeBSD port, we
+ can locate these files by doing
+
+ &prompt.user; find /usr/ports/lang/whizbang -name "*.el" -print
+
+
+ and install them by copying them into the Emacs site Lisp
+ directory. On FreeBSD 2.1.0-RELEASE, this is
+ /usr/local/share/emacs/site-lisp.
+
+ So for example, if the output from the find command
+ was
+
+ /usr/ports/lang/whizbang/work/misc/whizbang.el
+
+
+ we would do
+
+ &prompt.root; cp /usr/ports/lang/whizbang/work/misc/whizbang.el /usr/local/share/emacs/site-lisp
+
+
+ Next, we need to decide what extension whizbang source
+ files have. Let's say for the sake of argument that they all
+ end in .wiz. We need to add an entry to
+ our .emacs file to make sure Emacs will
+ be able to use the information in
+ whizbang.el.
+
+ Find the auto-mode-alist entry in
+ .emacs and add a line for whizbang, such
+ as:
+
+ …
+("\\.lsp$" . lisp-mode)
+("\\.wiz$" . whizbang-mode)
+("\\.scm$" . scheme-mode)
+…
+
+
+ This means that Emacs will automatically go into
+ whizbang-mode when you edit a file ending
+ in .wiz.
+
+ Just below this, you'll find the
+ font-lock-auto-mode-list entry. Add
+ whizbang-mode to it like so:
+
+ ;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'whizbang-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+
+ This means that Emacs will always enable
+ font-lock-mode (ie syntax highlighting)
+ when editing a .wiz file.
+
+ And that's all that's needed. If there's anything else
+ you want done automatically when you open up a
+ .wiz file, you can add a
+ whizbang-mode hook (see
+ my-scheme-mode-hook for a simple example
+ that adds auto-indent).
+
+
+
+
+ Further Reading
+
+
+
+ Brian Harvey and Matthew Wright
+ Simply Scheme
+ MIT 1994.
+ ISBN 0-262-08226-8
+
+
+
+ Randall Schwartz
+ Learning Perl
+ O'Reilly 1993
+ ISBN 1-56592-042-2
+
+
+
+ Patrick Henry Winston and Berthold Klaus Paul Horn
+ Lisp (3rd Edition)
+ Addison-Wesley 1989
+ ISBN 0-201-08319-1
+
+
+
+ Brian W. Kernighan and Rob Pike
+ The Unix Programming Environment
+ Prentice-Hall 1984
+ ISBN 0-13-937681-X
+
+
+
+ Brian W. Kernighan and Dennis M. Ritchie
+ The C Programming Language (2nd Edition)
+ Prentice-Hall 1988
+ ISBN 0-13-110362-8
+
+
+
+ Bjarne Stroustrup
+ The C++ Programming Language
+ Addison-Wesley 1991
+ ISBN 0-201-53992-6
+
+
+
+ W. Richard Stevens
+ Advanced Programming in the Unix Environment
+ Addison-Wesley 1992
+ ISBN 0-201-56317-7
+
+
+
+ W. Richard Stevens
+ Unix Network Programming
+ Prentice-Hall 1990
+ ISBN 0-13-949876-1
+
+
+
-
@@ -1357,7 +3598,7 @@ DRIVER_MODULE(mypci, pci, mypci_driver, mypci_devclass, 0, 0);
-
+ Debugging
diff --git a/en_US.ISO_8859-1/books/developers-handbook/book.sgml b/en_US.ISO_8859-1/books/developers-handbook/book.sgml
index 8aacd1d42a..bd58d4a25a 100644
--- a/en_US.ISO_8859-1/books/developers-handbook/book.sgml
+++ b/en_US.ISO_8859-1/books/developers-handbook/book.sgml
@@ -1,7 +1,7 @@
Basics
-
- Compilation
+
+ Programming Tools
- This will include things like: compilation, makefiles, .mk
- files, basic debugging, linking, secure programming
- guidelines, style(9), CVS, diff, patch, etc.
+ This chapter was written by James Raynard.
+ Modifications for the Developer's Handbook by Murray Stokely.
+
+
+ Synopsis
+
+ This document is an introduction to using some of the
+ programming tools supplied with FreeBSD, although much of it
+ will be applicable to many other versions of Unix. It does
+ not attempt to describe coding in any
+ detail. Most of the document assumes little or no previous
+ programming knowledge, although it is hoped that most
+ programmers will find something of value in it
+
+
+
+ Introduction
+
+ FreeBSD offers an excellent development environment.
+ Compilers for C, C++, and Fortran and an assembler come with the
+ basic system, not to mention a Perl interpreter and classic Unix
+ tools such as sed and awk.
+ If that is not enough, there are many more compilers and
+ interpreters in the Ports collection. FreeBSD is very
+ compatible with standards such as POSIX and
+ ANSI C, as well with its own BSD heritage, so
+ it is possible to write applications that will compile and run
+ with little or no modification on a wide range of
+ platforms.
+
+ However, all this power can be rather overwhelming at
+ first if you've never written programs on a Unix platform
+ before. This document aims to help you get up and running,
+ without getting too deeply into more advanced topics. The
+ intention is that this document should give you enough of the
+ basics to be able to make some sense of the
+ documentation.
+
+ Most of the document requires little or no knowledge of
+ programming, although it does assume a basic competence with
+ using Unix and a willingness to learn!
+
+
+
+
+ Introduction to Programming
+
+ A program is a set of instructions that tell the computer
+ to do various things; sometimes the instruction it has to
+ perform depends on what happened when it performed a previous
+ instruction. This section gives an overview of the two main
+ ways in which you can give these instructions, or
+ commands as they are usually called. One way
+ uses an interpreter, the other a
+ compiler. As human languages are too
+ difficult for a computer to understand in an unambiguous way,
+ commands are usually written in one or other languages specially
+ designed for the purpose.
+
+
+ Interpreters
+
+ With an interpreter, the language comes as an environment,
+ where you type in commands at a prompt and the environment
+ executes them for you. For more complicated programs, you can
+ type the commands into a file and get the interpreter to load
+ the file and execute the commands in it. If anything goes
+ wrong, many interpreters will drop you into a debugger to help
+ you track down the problem.
+
+ The advantage of this is that you can see the results of
+ your commands immediately, and mistakes can be corrected
+ readily. The biggest disadvantage comes when you want to
+ share your programs with someone. They must have the same
+ interpreter, or you must have some way of giving it to them,
+ and they need to understand how to use it. Also users may not
+ appreciate being thrown into a debugger if they press the
+ wrong key! From a performance point of view, interpreters can
+ use up a lot of memory, and generally do not generate code as
+ efficiently as compilers.
+
+ In my opinion, interpreted languages are the best way to
+ start if you have not done any programming before. This kind
+ of environment is typically found with languages like Lisp,
+ Smalltalk, Perl and Basic. It could also be argued that the
+ Unix shell (sh, csh) is itself an
+ interpreter, and many people do in fact write shell
+ scripts to help with various
+ housekeeping tasks on their machine. Indeed, part
+ of the original Unix philosophy was to provide lots of small
+ utility programs that could be linked together in shell
+ scripts to perform useful tasks.
+
+
+
+ Interpreters available with FreeBSD
+
+ Here is a list of interpreters that are available as
+ FreeBSD
+ packages, with a brief discussion of some of the
+ more popular interpreted languages.
+
+ To get one of these packages, all you need to do is to
+ click on the hotlink for the package, then run
+
+ &prompt.root; pkg_add package name
+
+
+ as root. Obviously, you will need to have a fully
+ functional FreeBSD 2.1.0 or later system for the package to
+ work!
+
+
+
+ BASIC
+
+
+ Short for Beginner's All-purpose Symbolic
+ Instruction Code. Developed in the 1950s for teaching
+ University students to program and provided with every
+ self-respecting personal computer in the 1980s,
+ BASIC has been the first programming
+ language for many programmers. It's also the foundation
+ for Visual Basic.
+
+ The Bywater
+ Basic Interpreter and the Phil
+ Cockroft's Basic Interpreter (formerly Rabbit
+ Basic) are available as FreeBSD FreeBSD
+ packages
+
+
+
+
+ Lisp
+
+
+ A language that was developed in the late 1950s as
+ an alternative to the number-crunching
+ languages that were popular at the time. Instead of
+ being based on numbers, Lisp is based on lists; in fact
+ the name is short for List Processing.
+ Very popular in AI (Artificial Intelligence)
+ circles.
+
+ Lisp is an extremely powerful and sophisticated
+ language, but can be rather large and unwieldy.
+
+ FreeBSD has GNU
+ Common Lisp available as a package.
+
+
+
+
+ Perl
+
+
+ Very popular with system administrators for writing
+ scripts; also often used on World Wide Web servers for
+ writing CGI scripts.
+
+ The latest version (version 5) comes with FreeBSD.
+
+
+
+
+ Scheme
+
+
+ A dialect of Lisp that is rather more compact and
+ cleaner than Common Lisp. Popular in Universities as it
+ is simple enough to teach to undergraduates as a first
+ language, while it has a high enough level of
+ abstraction to be used in research work.
+
+ FreeBSD has packages of the Elk
+ Scheme Interpreter, the MIT
+ Scheme Interpreter and the SCM
+ Scheme Interpreter.
+
+
+
+
+ Icon
+
+
+ The
+ Icon Programming Language.
+
+
+
+
+ Logo
+
+
+ Brian
+ Harvey's LOGO Interpreter.
+
+
+
+
+ Python
+
+
+ The
+ Python Object-Oriented Programming
+ Language
+
+
+
+
+
+
+ Compilers
+
+ Compilers are rather different. First of all, you write
+ your code in a file (or files) using an editor. You then run
+ the compiler and see if it accepts your program. If it did
+ not compile, grit your teeth and go back to the editor; if it
+ did compile and gave you a program, you can run it either at a
+ shell command prompt or in a debugger to see if it works
+ properly.
+
+
+ If you run it in the shell, you may get a core
+ dump.
+
+
+ Obviously, this is not quite as direct as using an
+ interpreter. However it allows you to do a lot of things
+ which are very difficult or even impossible with an
+ interpreter, such as writing code which interacts closely with
+ the operating system—or even writing your own operating
+ system! It's also useful if you need to write very efficient
+ code, as the compiler can take its time and optimise the code,
+ which would not be acceptable in an interpreter. And
+ distributing a program written for a compiler is usually more
+ straightforward than one written for an interpreter—you
+ can just give them a copy of the executable, assuming they
+ have the same operating system as you.
+
+ Compiled languages include Pascal, C and C++. C and C++
+ are rather unforgiving languages, and best suited to more
+ experienced programmers; Pascal, on the other hand, was
+ designed as an educational language, and is quite a good
+ language to start with. Unfortunately, FreeBSD doesn't have
+ any Pascal support, except for a Pascal-to-C converter in the
+ ports.
+
+ As the edit-compile-run-debug cycle is rather tedious when
+ using separate programs, many commercial compiler makers have
+ produced Integrated Development Environments
+
+ (IDEs for short). FreeBSD does not have an
+ IDE as such; however it is possible to use Emacs
+ for this purpose. This is discussed in .
+
+
+
+
+
+
+
+ Compiling with <command>cc</command>
+
+ This section deals only with the GNU compiler for C and C++,
+ since that comes with the base FreeBSD system. It can be
+ invoked by either cc or gcc. The
+ details of producing a program with an interpreter vary
+ considerably between interpreters, and are usually well covered
+ in the documentation and on-line help for the
+ interpreter.
+
+ Once you've written your masterpiece, the next step is to
+ convert it into something that will (hopefully!) run on FreeBSD.
+ This usually involves several steps, each of which is done by a
+ separate program.
+
+
+
+ Pre-process your source code to remove comments and do
+ other tricks like expanding macros in C.
+
+
+
+ Check the syntax of your code to see if you have obeyed
+ the rules of the language. If you have not, it will
+ complain!
+
+
+
+ Convert the source code into assembly
+ language—this is very close to machine code, but still
+ understandable by humans. Allegedly.
+
+
+ To be strictly accurate, cc converts the
+ source code into its own, machine-independent
+ p-code instead of assembly language at
+ this stage.
+
+
+
+
+ Convert the assembly language into machine
+ code—yep, we are talking bits and bytes, ones and
+ zeros here.
+
+
+
+ Check that you have used things like functions and
+ global variables in a consistent way. For example, if you
+ have called a non-existent function, it will
+ complain.
+
+
+
+ If you are trying to produce an executable from several
+ source code files, work out how to fit them all
+ together.
+
+
+
+ Work out how to produce something that the system's
+ run-time loader will be able to load into memory and
+ run.
+
+
+
+ Finally, write the executable on the file system.
+
+
+
+ The word compiling is often used to refer to
+ just steps 1 to 4—the others are referred to as
+ linking. Sometimes step 1 is referred to as
+ pre-processing and steps 3-4 as
+ assembling.
+
+ Fortunately, almost all this detail is hidden from you, as
+ cc is a front end that manages calling all these
+ programs with the right arguments for you; simply typing
+
+ &prompt.user; cc foobar.c
+
+
+ will cause foobar.c to be compiled by all the
+ steps above. If you have more than one file to compile, just do
+ something like
+
+ &prompt.user; cc foo.c bar.c
+
+
+ Note that the syntax checking is just that—checking
+ the syntax. It will not check for any logical mistakes you may
+ have made, like putting the program into an infinite loop, or
+ using a bubble sort when you meant to use a binary
+ sort.
+
+
+ In case you didn't know, a binary sort is an efficient
+ way of sorting things into order and a bubble sort
+ isn't.
+
+
+ There are lots and lots of options for cc, which
+ are all in the man page. Here are a few of the most important
+ ones, with examples of how to use them.
+
+
+
+
+
+
+ The output name of the file. If you do not use this
+ option, cc will produce an executable called
+ a.out.
+
+
+ The reasons for this are buried in the mists of
+ history.
+
+
+
+ &prompt.user; cc foobar.c executable is a.out
+&prompt.user; cc -o foobar foobar.c executable is foobar
+
+
+
+
+
+
+
+
+
+ Just compile the file, do not link it. Useful for toy
+ programs where you just want to check the syntax, or if
+ you are using a Makefile.
+
+
+ &prompt.user; cc -c foobar.c
+
+
+
+ This will produce an object file (not an
+ executable) called foobar.o. This
+ can be linked together with other object files into an
+ executable.
+
+
+
+
+
+
+
+ Create a debug version of the executable. This makes
+ the compiler put information into the executable about
+ which line of which source file corresponds to which
+ function call. A debugger can use this information to show
+ the source code as you step through the program, which is
+ very useful; the disadvantage is that
+ all this extra information makes the program much bigger.
+ Normally, you compile with while you
+ are developing a program and then compile a release
+ version without when you're
+ satisfied it works properly.
+
+
+ &prompt.user; cc -g foobar.c
+
+
+
+ This will produce a debug version of the
+ program.
+
+
+ Note, we didn't use the flag
+ to specify the executable name, so we will get an
+ executable called a.out.
+ Producing a debug version called
+ foobar is left as an exercise for
+ the reader!
+
+
+
+
+
+
+
+
+ Create an optimised version of the executable. The
+ compiler performs various clever tricks to try and produce
+ an executable that runs faster than normal. You can add a
+ number after the to specify a higher
+ level of optimisation, but this often exposes bugs in the
+ compiler's optimiser. For instance, the version of
+ cc that comes with the 2.1.0 release of
+ FreeBSD is known to produce bad code with the
+ option in some circumstances.
+
+ Optimisation is usually only turned on when compiling
+ a release version.
+
+
+ &prompt.user; cc -O -o foobar foobar.c
+
+
+
+ This will produce an optimised version of
+ foobar.
+
+
+
+
+ The following three flags will force cc
+ to check that your code complies to the relevant international
+ standard, often referred to as the ANSI
+ standard, though strictly speaking it is an
+ ISO standard.
+
+
+
+
+
+
+ Enable all the warnings which the authors of
+ cc believe are worthwhile. Despite the
+ name, it will not enable all the warnings
+ cc is capable of.
+
+
+
+
+
+
+
+ Turn off most, but not all, of the
+ non-ANSI C features provided by
+ cc. Despite the name, it does not
+ guarantee strictly that your code will comply to the
+ standard.
+
+
+
+
+
+
+
+ Turn off all
+ cc's non-ANSI C
+ features.
+
+
+
+
+ Without these flags, cc will allow you to
+ use some of its non-standard extensions to the standard. Some
+ of these are very useful, but will not work with other
+ compilers—in fact, one of the main aims of the standard is
+ to allow people to write code that will work with any compiler
+ on any system. This is known as portable
+ code.
+
+ Generally, you should try to make your code as portable as
+ possible, as otherwise you may have to completely re-write the
+ program later to get it to work somewhere else—and who
+ knows what you may be using in a few years time?
+
+
+ &prompt.user; cc -Wall -ansi -pedantic -o foobar foobar.c
+
+
+
+ This will produce an executable foobar
+ after checking foobar.c for standard
+ compliance.
+
+
+
+
+
+
+ Specify a function library to be used during when
+ linking.
+
+ The most common example of this is when compiling a
+ program that uses some of the mathematical functions in C.
+ Unlike most other platforms, these are in a separate
+ library from the standard C one and you have to tell the
+ compiler to add it.
+
+ The rule is that if the library is called
+ libsomething.a,
+ you give cc the argument
+ .
+ For example, the math library is
+ libm.a, so you give
+ cc the argument .
+ A common gotcha with the math library is
+ that it has to be the last library on the command
+ line.
+
+
+ &prompt.user; cc -o foobar foobar.c -lm
+
+
+
+ This will link the math library functions into
+ foobar.
+
+ If you are compiling C++ code, you need to add
+ , or if
+ you are using FreeBSD 2.2 or later, to the command line
+ argument to link the C++ library functions.
+ Alternatively, you can run c++ instead
+ of cc, which does this for you.
+ c++ can also be invoked as
+ g++ on FreeBSD.
+
+
+ &prompt.user; cc -o foobar foobar.cc -lg++For FreeBSD 2.1.6 and earlier
+&prompt.user; cc -o foobar foobar.cc -lstdc++For FreeBSD 2.2 and later
+&prompt.user; c++ -o foobar foobar.cc
+
+
+
+ Each of these will both produce an executable
+ foobar from the C++ source file
+ foobar.cc. Note that, on Unix
+ systems, C++ source files traditionally end in
+ .C, .cxx or
+ .cc, rather than the
+ MS-DOS style
+ .cpp (which was already used for
+ something else). gcc used to rely on
+ this to work out what kind of compiler to use on the
+ source file; however, this restriction no longer applies,
+ so you may now call your C++ files
+ .cpp with impunity!
+
+
+
+
+
+ Common <command>cc</command> Queries and Problems
+
+
+
+
+ I am trying to write a program which uses the
+ sin() function and I get an error
+ like this. What does it mean?
+
+
+ /var/tmp/cc0143941.o: Undefined symbol `_sin' referenced from text segment
+
+
+
+
+
+ When using mathematical functions like
+ sin(), you have to tell
+ cc to link in the math library, like
+ so:
+
+
+ &prompt.user; cc -o foobar foobar.c -lm
+
+
+
+
+
+
+
+ All right, I wrote this simple program to practice
+ using . All it does is raise 2.1 to
+ the power of 6.
+
+
+ #include <stdio.h>
+
+int main() {
+ float f;
+
+ f = pow(2.1, 6);
+ printf("2.1 ^ 6 = %f\n", f);
+ return 0;
+}
+
+
+
+ and I compiled it as:
+
+
+ &prompt.user; cc temp.c -lm
+
+
+
+ like you said I should, but I get this when I run
+ it:
+
+
+ &prompt.user; ./a.out
+2.1 ^ 6 = 1023.000000
+
+
+
+ This is not the right answer!
+ What is going on?
+
+
+
+ When the compiler sees you call a function, it
+ checks if it has already seen a prototype for it. If it
+ has not, it assumes the function returns an
+ int, which is definitely not what you want
+ here.
+
+
+
+
+
+ So how do I fix this?
+
+
+
+ The prototypes for the mathematical functions are in
+ math.h. If you include this file,
+ the compiler will be able to find the prototype and it
+ will stop doing strange things to your
+ calculation!
+
+
+ #include <math.h>
+#include <stdio.h>
+
+int main() {
+...
+
+
+
+ After recompiling it as you did before, run
+ it:
+
+
+ &prompt.user; ./a.out
+2.1 ^ 6 = 85.766121
+
+
+
+ If you are using any of the mathematical functions,
+ always include
+ math.h and remember to link in the
+ math library.
+
+
+
+
+
+ I compiled a file called
+ foobar.c and I cannot find an
+ executable called foobar. Where's
+ it gone?
+
+
+
+ Remember, cc will call the
+ executable a.out unless you tell it
+ differently. Use the
+
+ option:
+
+
+ &prompt.user; cc -o foobar foobar.c
+
+
+
+
+
+
+
+ OK, I have an executable called
+ foobar, I can see it when I run
+ ls, but when I type in
+ foobar at the command prompt it tells
+ me there is no such file. Why can it not find
+ it?
+
+
+
+ Unlike MS-DOS, Unix does not
+ look in the current directory when it is trying to find
+ out which executable you want it to run, unless you tell
+ it to. Either type ./foobar, which
+ means run the file called
+ foobar in the current
+ directory, or change your PATH environment
+ variable so that it looks something like
+
+
+ bin:/usr/bin:/usr/local/bin:.
+
+
+
+ The dot at the end means look in the current
+ directory if it is not in any of the
+ others.
+
+
+
+
+
+ I called my executable test,
+ but nothing happens when I run it. What is going
+ on?
+
+
+
+ Most Unix systems have a program called
+ test in /usr/bin
+ and the shell is picking that one up before it gets to
+ checking the current directory. Either type:
+
+
+ &prompt.user; ./test
+
+
+
+ or choose a better name for your program!
+
+
+
+
+
+ I compiled my program and it seemed to run all right
+ at first, then there was an error and it said something
+ about core dumped. What does that
+ mean?
+
+
+
+ The name core dump dates back
+ to the very early days of Unix, when the machines used
+ core memory for storing data. Basically, if the program
+ failed under certain conditions, the system would write
+ the contents of core memory to disk in a file called
+ core, which the programmer could
+ then pore over to find out what went wrong.
+
+
+
+
+
+ Fascinating stuff, but what I am supposed to do
+ now?
+
+
+
+ Use gdb to analyse the core (see
+ ).
+
+
+
+
+
+ When my program dumped core, it said something about
+ a segmentation fault. What's
+ that?
+
+
+
+ This basically means that your program tried to
+ perform some sort of illegal operation on memory; Unix
+ is designed to protect the operating system and other
+ programs from rogue programs.
+
+ Common causes for this are:
+
+
+
+ Trying to write to a NULL
+ pointer, eg
+
+ char *foo = NULL;
+strcpy(foo, "bang!");
+
+
+
+
+ Using a pointer that hasn't been initialised,
+ eg
+
+ char *foo;
+strcpy(foo, "bang!");
+
+
+ The pointer will have some random value that,
+ with luck, will point into an area of memory that
+ isn't available to your program and the kernel will
+ kill your program before it can do any damage. If
+ you're unlucky, it'll point somewhere inside your
+ own program and corrupt one of your data structures,
+ causing the program to fail mysteriously.
+
+
+
+ Trying to access past the end of an array,
+ eg
+
+ int bar[20];
+bar[27] = 6;
+
+
+
+
+ Trying to store something in read-only memory,
+ eg
+
+ char *foo = "My string";
+strcpy(foo, "bang!");
+
+
+ Unix compilers often put string literals like
+ "My string" into read-only areas
+ of memory.
+
+
+
+ Doing naughty things with
+ malloc() and
+ free(), eg
+
+ char bar[80];
+free(bar);
+
+
+ or
+
+ char *foo = malloc(27);
+free(foo);
+free(foo);
+
+
+
+
+ Making one of these mistakes will not always lead to
+ an error, but they are always bad practice. Some
+ systems and compilers are more tolerant than others,
+ which is why programs that ran well on one system can
+ crash when you try them on an another.
+
+
+
+
+
+ Sometimes when I get a core dump it says
+ bus error. It says in my Unix
+ book that this means a hardware problem, but the
+ computer still seems to be working. Is this
+ true?
+
+
+
+ No, fortunately not (unless of course you really do
+ have a hardware problem…). This is usually
+ another way of saying that you accessed memory in a way
+ you shouldn't have.
+
+
+
+
+
+ This dumping core business sounds as though it could
+ be quite useful, if I can make it happen when I want to.
+ Can I do this, or do I have to wait until there's an
+ error?
+
+
+
+ Yes, just go to another console or xterm, do
+
+ &prompt.user; ps
+
+
+ to find out the process ID of your program, and
+ do
+
+ &prompt.user; kill -ABRT pid
+
+
+ where
+ pid is
+ the process ID you looked up.
+
+ This is useful if your program has got stuck in an
+ infinite loop, for instance. If your program happens to
+ trap SIGABRT, there are several other
+ signals which have a similar effect.
+
+
+
+
+
+
+
+ Make
+
+
+ What is <command>make</command>?
+
+ When you're working on a simple program with only one or
+ two source files, typing in
+
+ &prompt.user; cc file1.c file2.c
+
+
+ is not too bad, but it quickly becomes very tedious when
+ there are several files—and it can take a while to
+ compile, too.
+
+ One way to get around this is to use object files and only
+ recompile the source file if the source code has changed. So
+ we could have something like:
+
+ &prompt.user; cc file1.o file2.o … file37.c &hellip
+
+
+ if we'd changed file37.c, but not any
+ of the others, since the last time we compiled. This may
+ speed up the compilation quite a bit, but doesn't solve the
+ typing problem.
+
+ Or we could write a shell script to solve the typing
+ problem, but it would have to re-compile everything, making it
+ very inefficient on a large project.
+
+ What happens if we have hundreds of source files lying
+ about? What if we're working in a team with other people who
+ forget to tell us when they've changed one of their source
+ files that we use?
+
+ Perhaps we could put the two solutions together and write
+ something like a shell script that would contain some kind of
+ magic rule saying when a source file needs compiling. Now all
+ we need now is a program that can understand these rules, as
+ it's a bit too complicated for the shell.
+
+ This program is called make. It reads
+ in a file, called a makefile, that
+ tells it how different files depend on each other, and works
+ out which files need to be re-compiled and which ones don't.
+ For example, a rule could say something like if
+ fromboz.o is older than
+ fromboz.c, that means someone must have
+ changed fromboz.c, so it needs to be
+ re-compiled. The makefile also has rules telling
+ make how to re-compile the source file,
+ making it a much more powerful tool.
+
+ Makefiles are typically kept in the same directory as the
+ source they apply to, and can be called
+ makefile, Makefile
+ or MAKEFILE. Most programmers use the
+ name Makefile, as this puts it near the
+ top of a directory listing, where it can easily be
+ seen.
+
+
+ They don't use the MAKEFILE form
+ as block capitals are often used for documentation files
+ like README.
+
+
+
+
+ Example of using <command>make</command>
+
+ Here's a very simple make file:
+
+ foo: foo.c
+ cc -o foo foo.c
+
+
+ It consists of two lines, a dependency line and a creation
+ line.
+
+ The dependency line here consists of the name of the
+ program (known as the target), followed
+ by a colon, then whitespace, then the name of the source file.
+ When make reads this line, it looks to see
+ if foo exists; if it exists, it compares
+ the time foo was last modified to the
+ time foo.c was last modified. If
+ foo does not exist, or is older than
+ foo.c, it then looks at the creation line
+ to find out what to do. In other words, this is the rule for
+ working out when foo.c needs to be
+ re-compiled.
+
+ The creation line starts with a tab (press
+ the tab key) and then the command you would
+ type to create foo if you were doing it
+ at a command prompt. If foo is out of
+ date, or does not exist, make then executes
+ this command to create it. In other words, this is the rule
+ which tells make how to re-compile
+ foo.c.
+
+ So, when you type make, it will
+ make sure that foo is up to date with
+ respect to your latest changes to foo.c.
+ This principle can be extended to
+ Makefiles with hundreds of
+ targets—in fact, on FreeBSD, it is possible to compile
+ the entire operating system just by typing make
+ world in the appropriate directory!
+
+ Another useful property of makefiles is that the targets
+ don't have to be programs. For instance, we could have a make
+ file that looks like this:
+
+ foo: foo.c
+ cc -o foo foo.c
+
+install:
+ cp foo /home/me
+
+
+ We can tell make which target we want to make by
+ typing:
+
+ &prompt.user; make target
+
+
+ make will then only look at that target
+ and ignore any others. For example, if we type
+ make foo with the makefile above, make
+ will ignore the install target.
+
+ If we just type make on its own,
+ make will always look at the first target and then stop
+ without looking at any others. So if we typed
+ make here, it will just go to the
+ foo target, re-compile
+ foo if necessary, and then stop without
+ going on to the install target.
+
+ Notice that the install target doesn't
+ actually depend on anything! This means that the command on
+ the following line is always executed when we try to make that
+ target by typing make install. In this
+ case, it will copy foo into the user's
+ home directory. This is often used by application makefiles,
+ so that the application can be installed in the correct
+ directory when it has been correctly compiled.
+
+ This is a slightly confusing subject to try and explain.
+ If you don't quite understand how make
+ works, the best thing to do is to write a simple program like
+ hello world and a make file like the one above
+ and experiment. Then progress to using more than one source
+ file, or having the source file include a header file. The
+ touch command is very useful here—it
+ changes the date on a file without you having to edit
+ it.
+
+
+
+ FreeBSD Makefiles
+
+ Makefiles can be rather complicated to write. Fortunately,
+ BSD-based systems like FreeBSD come with some very powerful
+ ones as part of the system. One very good example of this is
+ the FreeBSD ports system. Here's the essential part of a
+ typical ports Makefile:
+
+ MASTER_SITES= ftp://freefall.cdrom.com/pub/FreeBSD/LOCAL_PORTS/
+DISTFILES= scheme-microcode+dist-7.3-freebsd.tgz
+
+.include <bsd.port.mk>
+
+
+ Now, if we go to the directory for this port and type
+ make, the following happens:
+
+
+
+ A check is made to see if the source code for this
+ port is already on the system.
+
+
+
+ If it isn't, an FTP connection to the URL in
+ MASTER_SITES is set up to download the
+ source.
+
+
+
+ The checksum for the source is calculated and compared
+ it with one for a known, good, copy of the source. This
+ is to make sure that the source was not corrupted while in
+ transit.
+
+
+
+ Any changes required to make the source work on
+ FreeBSD are applied—this is known as
+ patching.
+
+
+
+ Any special configuration needed for the source is
+ done. (Many Unix program distributions try to work out
+ which version of Unix they are being compiled on and which
+ optional Unix features are present—this is where
+ they are given the information in the FreeBSD ports
+ scenario).
+
+
+
+ The source code for the program is compiled. In
+ effect, we change to the directory where the source was
+ unpacked and do make—the
+ program's own make file has the necessary information to
+ build the program.
+
+
+
+ We now have a compiled version of the program. If we
+ wish, we can test it now; when we feel confident about the
+ program, we can type make install.
+ This will cause the program and any supporting files it
+ needs to be copied into the correct location; an entry is
+ also made into a package database, so
+ that the port can easily be uninstalled later if we change
+ our mind about it.
+
+
+
+ Now I think you'll agree that's rather impressive for a
+ four line script!
+
+ The secret lies in the last line, which tells
+ make to look in the system makefile called
+ bsd.port.mk. It's easy to overlook this
+ line, but this is where all the clever stuff comes
+ from—someone has written a makefile that tells
+ make to do all the things above (plus a
+ couple of other things I didn't mention, including handling
+ any errors that may occur) and anyone can get access to that
+ just by putting a single line in their own make file!
+
+ If you want to have a look at these system makefiles,
+ they're in /usr/share/mk, but it's
+ probably best to wait until you've had a bit of practice with
+ makefiles, as they are very complicated (and if you do look at
+ them, make sure you have a flask of strong coffee
+ handy!)
+
+
+
+ More advanced uses of <command>make</command>
+
+ Make is a very powerful tool, and can
+ do much more than the simple example above shows.
+ Unfortunately, there are several different versions of
+ make, and they all differ considerably.
+ The best way to learn what they can do is probably to read the
+ documentation—hopefully this introduction will have
+ given you a base from which you can do this.
+
+ The version of make that comes with FreeBSD is the
+ Berkeley make; there is a tutorial
+ for it in /usr/share/doc/psd/12.make. To
+ view it, do
+
+ &prompt.user; zmore paper.ascii.gz
+
+
+ in that directory.
+
+ Many applications in the ports use GNU
+ make, which has a very good set of
+ info pages. If you have installed any of these
+ ports, GNU make will automatically
+ have been installed as gmake. It's also
+ available as a port and package in its own right.
+
+ To view the info pages for GNU
+ make, you will have to edit the
+ dir file in the
+ /usr/local/info directory to add an entry
+ for it. This involves adding a line like
+
+ * Make: (make). The GNU Make utility.
+
+
+ to the file. Once you have done this, you can type
+ info and then select
+ make from the menu (or in
+ Emacs, do C-h
+ i).
+
+
+
+
+ Debugging
+
+
+ The Debugger
+
+ The debugger that comes with FreeBSD is called
+ gdb (GNU
+ debugger). You start it up by typing
+
+ &prompt.user; gdb progname
+
+
+ although most people prefer to run it inside
+ Emacs. You can do this by:
+
+ M-x gdb RET progname RET
+
+
+ Using a debugger allows you to run the program under more
+ controlled circumstances. Typically, you can step through the
+ program a line at a time, inspect the value of variables,
+ change them, tell the debugger to run up to a certain point
+ and then stop, and so on. You can even attach to a program
+ that's already running, or load a core file to investigate why
+ the program crashed. It's even possible to debug the kernel,
+ though that's a little trickier than the user applications
+ we'll be discussing in this section.
+
+ gdb has quite good on-line help, as
+ well as a set of info pages, so this section will concentrate
+ on a few of the basic commands.
+
+ Finally, if you find its text-based command-prompt style
+ off-putting, there's a graphical front-end for it xxgdb in the ports
+ collection.
+
+ This section is intended to be an introduction to using
+ gdb and does not cover specialised topics
+ such as debugging the kernel.
+
+
+
+ Running a program in the debugger
+
+ You'll need to have compiled the program with the
+ option to get the most out of using
+ gdb. It will work without, but you'll only
+ see the name of the function you're in, instead of the source
+ code. If you see a line like:
+
+ … (no debugging symbols found) …
+
+
+ when gdb starts up, you'll know that
+ the program wasn't compiled with the
+ option.
+
+ At the gdb prompt, type
+ break main. This will tell the
+ debugger to skip over the preliminary set-up code in the
+ program and start at the beginning of your code. Now type
+ run to start the program—it will
+ start at the beginning of the set-up code and then get stopped
+ by the debugger when it calls main().
+ (If you've ever wondered where main()
+ gets called from, now you know!).
+
+ You can now step through the program, a line at a time, by
+ pressing n. If you get to a function call,
+ you can step into it by pressing s. Once
+ you're in a function call, you can return from stepping into a
+ function call by pressing f. You can also
+ use up and down to take
+ a quick look at the caller.
+
+ Here's a simple example of how to spot a mistake in a
+ program with gdb. This is our program
+ (with a deliberate mistake):
+
+ #include <stdio.h>
+
+int bazz(int anint);
+
+main() {
+ int i;
+
+ printf("This is my program\n");
+ bazz(i);
+ return 0;
+}
+
+int bazz(int anint) {
+ printf("You gave me %d\n", anint);
+ return anint;
+}
+
+
+ This program sets i to be
+ 5 and passes it to a function
+ bazz() which prints out the number we
+ gave it.
+
+ When we compile and run the program we get
+
+ &prompt.user; cc -g -o temp temp.c
+&prompt.user; ./temp
+This is my program
+anint = 4231
+
+
+ That wasn't what we expected! Time to see what's going
+ on!
+
+ &prompt.user; gdb temp
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) break main Skip the set-up code
+Breakpoint 1 at 0x160f: file temp.c, line 9. gdb puts breakpoint at main()
+(gdb) run Run as far as main()
+Starting program: /home/james/tmp/temp Program starts running
+
+Breakpoint 1, main () at temp.c:9 gdb stops at main()
+(gdb) n Go to next line
+This is my program Program prints out
+(gdb) s step into bazz()
+bazz (anint=4231) at temp.c:17 gdb displays stack frame
+(gdb)
+
+
+ Hang on a minute! How did anint get to be
+ 4231? Didn't we set it to be
+ 5 in main()? Let's
+ move up to main() and have a look.
+
+ (gdb) up Move up call stack
+#1 0x1625 in main () at temp.c:11 gdb displays stack frame
+(gdb) p i Show us the value of i
+$1 = 4231 gdb displays 4231
+
+
+ Oh dear! Looking at the code, we forgot to initialise
+ i. We meant to put
+
+ …
+main() {
+ int i;
+
+ i = 5;
+ printf("This is my program\n");
+&hellip
+
+
+ but we left the i=5; line out. As we
+ didn't initialise i, it had whatever number
+ happened to be in that area of memory when the program ran,
+ which in this case happened to be
+ 4231.
+
+
+ gdb displays the stack frame every
+ time we go into or out of a function, even if we're using
+ up and down to move
+ around the call stack. This shows the name of the function
+ and the values of its arguments, which helps us keep track
+ of where we are and what's going on. (The stack is a
+ storage area where the program stores information about the
+ arguments passed to functions and where to go when it
+ returns from a function call).
+
+
+
+
+ Examining a core file
+
+ A core file is basically a file which contains the
+ complete state of the process when it crashed. In the
+ good old days, programmers had to print out hex
+ listings of core files and sweat over machine code manuals,
+ but now life is a bit easier. Incidentally, under FreeBSD and
+ other 4.4BSD systems, a core file is called
+ progname.core instead of just
+ core, to make it clearer which program a
+ core file belongs to.
+
+ To examine a core file, start up gdb in
+ the usual way. Instead of typing break or
+ run, type
+
+ (gdb) core progname.core
+
+
+ If you're not in the same directory as the core file,
+ you'll have to do dir
+ /path/to/core/file first.
+
+ You should see something like this:
+
+ &prompt.user; gdb a.out
+GDB is free software and you are welcome to distribute copies of it
+ under certain conditions; type "show copying" to see the conditions.
+There is absolutely no warranty for GDB; type "show warranty" for details.
+GDB 4.13 (i386-unknown-freebsd), Copyright 1994 Free Software Foundation, Inc.
+(gdb) core a.out.core
+Core was generated by `a.out'.
+Program terminated with signal 11, Segmentation fault.
+Cannot access memory at address 0x7020796d.
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+(gdb)
+
+
+ In this case, the program was called
+ a.out, so the core file is called
+ a.out.core. We can see that the program
+ crashed due to trying to access an area in memory that was not
+ available to it in a function called
+ bazz.
+
+ Sometimes it's useful to be able to see how a function was
+ called, as the problem could have occurred a long way up the
+ call stack in a complex program. The bt
+ command causes gdb to print out a
+ back-trace of the call stack:
+
+ (gdb) bt
+#0 0x164a in bazz (anint=0x5) at temp.c:17
+#1 0xefbfd888 in end ()
+#2 0x162c in main () at temp.c:11
+(gdb)
+
+
+ The end() function is called when a
+ program crashes; in this case, the bazz()
+ function was called from main().
+
+
+
+ Attaching to a running program
+
+ One of the neatest features about gdb
+ is that it can attach to a program that's already running. Of
+ course, that assumes you have sufficient permissions to do so.
+ A common problem is when you are stepping through a program
+ that forks, and you want to trace the child, but the debugger
+ will only let you trace the parent.
+
+ What you do is start up another gdb,
+ use ps to find the process ID for the
+ child, and do
+
+ (gdb) attach pid
+
+
+ in gdb, and then debug as usual.
+
+ That's all very well, you're probably
+ thinking, but by the time I've done that, the child
+ process will be over the hill and far away. Fear
+ not, gentle reader, here's how to do it (courtesy of the
+ gdb info pages):
+
+ &hellip
+if ((pid = fork()) < 0) /* _Always_ check this */
+ error();
+else if (pid == 0) { /* child */
+ int PauseMode = 1;
+
+ while (PauseMode)
+ sleep(10); /* Wait until someone attaches to us */
+ &hellip
+} else { /* parent */
+ &hellip
+
+
+ Now all you have to do is attach to the child, set
+ PauseMode to 0, and wait
+ for the sleep() call to return!
+
+
+
+
+ Using Emacs as a Development Environment
+
+
+ Emacs
+
+ Unfortunately, Unix systems don't come with the kind of
+ everything-you-ever-wanted-and-lots-more-you-didn't-in-one-gigantic-package
+ integrated development environments that other systems
+ have.
+
+
+ At least, not unless you pay out very large sums of
+ money.
+
+
+ However, it is possible to set up your own environment. It
+ may not be as pretty, and it may not be quite as integrated,
+ but you can set it up the way you want it. And it's free.
+ And you have the source to it.
+
+ The key to it all is Emacs. Now there are some people who
+ loathe it, but many who love it. If you're one of the former,
+ I'm afraid this section will hold little of interest to you.
+ Also, you'll need a fair amount of memory to run it—I'd
+ recommend 8MB in text mode and 16MB in X as the bare minimum
+ to get reasonable performance.
+
+ Emacs is basically a highly customisable
+ editor—indeed, it has been customised to the point where
+ it's more like an operating system than an editor! Many
+ developers and sysadmins do in fact spend practically all
+ their time working inside Emacs, leaving it only to log
+ out.
+
+ It's impossible even to summarise everything Emacs can do
+ here, but here are some of the features of interest to
+ developers:
+
+
+
+ Very powerful editor, allowing search-and-replace on
+ both strings and regular expressions (patterns), jumping
+ to start/end of block expression, etc, etc.
+
+
+
+ Pull-down menus and online help.
+
+
+
+ Language-dependent syntax highlighting and
+ indentation.
+
+
+
+ Completely customisable.
+
+
+
+ You can compile and debug programs within
+ Emacs.
+
+
+
+ On a compilation error, you can jump to the offending
+ line of source code.
+
+
+
+ Friendly-ish front-end to the info
+ program used for reading GNU hypertext documentation,
+ including the documentation on Emacs itself.
+
+
+
+ Friendly front-end to gdb, allowing
+ you to look at the source code as you step through your
+ program.
+
+
+
+ You can read Usenet news and mail while your program
+ is compiling.
+
+
+
+ And doubtless many more that I've overlooked.
+
+ Emacs can be installed on FreeBSD using the Emacs
+ port.
+
+ Once it's installed, start it up and do C-h
+ t to read an Emacs tutorial—that means
+ hold down the control key, press
+ h, let go of the control
+ key, and then press t. (Alternatively, you
+ can you use the mouse to select Emacs
+ Tutorial from the Help
+ menu).
+
+ Although Emacs does have menus, it's well worth learning
+ the key bindings, as it's much quicker when you're editing
+ something to press a couple of keys than to try and find the
+ mouse and then click on the right place. And, when you're
+ talking to seasoned Emacs users, you'll find they often
+ casually throw around expressions like M-x
+ replace-s RET foo RET bar RET so it's
+ useful to know what they mean. And in any case, Emacs has far
+ too many useful functions for them to all fit on the menu
+ bars.
+
+ Fortunately, it's quite easy to pick up the key-bindings,
+ as they're displayed next to the menu item. My advice is to
+ use the menu item for, say, opening a file until you
+ understand how it works and feel confident with it, then try
+ doing C-x C-f. When you're happy with that, move on to
+ another menu command.
+
+ If you can't remember what a particular combination of
+ keys does, select Describe Key from
+ the Help menu and type it in—Emacs
+ will tell you what it does. You can also use the
+ Command Apropos menu item to find
+ out all the commands which contain a particular word in them,
+ with the key binding next to it.
+
+ By the way, the expression above means hold down the
+ Meta key, press x, release
+ the Meta key, type
+ replace-s (short for
+ replace-string—another feature of
+ Emacs is that you can abbreviate commands), press the
+ return key, type foo
+ (the string you want replaced), press the
+ return key, type bar (the string you want to
+ replace foo with) and press
+ return again. Emacs will then do the
+ search-and-replace operation you've just requested.
+
+ If you're wondering what on earth the
+ Meta key is, it's a special key that many
+ Unix workstations have. Unfortunately, PC's don't have one,
+ so it's usually the alt key (or if you're
+ unlucky, the escape key).
+
+ Oh, and to get out of Emacs, do C-x C-c
+ (that means hold down the control key, press
+ x, press c and release the
+ control key). If you have any unsaved files
+ open, Emacs will ask you if you want to save them. (Ignore
+ the bit in the documentation where it says
+ C-z is the usual way to leave
+ Emacs—that leaves Emacs hanging around in the
+ background, and is only really useful if you're on a system
+ which doesn't have virtual terminals).
+
+
+
+ Configuring Emacs
+
+ Emacs does many wonderful things; some of them are built
+ in, some of them need to be configured.
+
+ Instead of using a proprietary macro language for
+ configuration, Emacs uses a version of Lisp specially adapted
+ for editors, known as Emacs Lisp. This can be quite useful if
+ you want to go on and learn something like Common Lisp, as
+ it's considerably smaller than Common Lisp (although still
+ quite big!).
+
+ The best way to learn Emacs Lisp is to download the Emacs
+ Tutorial
+
+ However, there's no need to actually know any Lisp to get
+ started with configuring Emacs, as I've included a sample
+ .emacs file, which should be enough to
+ get you started. Just copy it into your home directory and
+ restart Emacs if it's already running; it will read the
+ commands from the file and (hopefully) give you a useful basic
+ setup.
+
+
+
+ A sample <filename>.emacs</filename> file
+
+ Unfortunately, there's far too much here to explain it in
+ detail; however there are one or two points worth
+ mentioning.
+
+
+
+ Everything beginning with a ; is a comment
+ and is ignored by Emacs.
+
+
+
+ In the first line, the
+ -*- Emacs-Lisp -*- is so that
+ we can edit the .emacs file itself
+ within Emacs and get all the fancy features for editing
+ Emacs Lisp. Emacs usually tries to guess this based on
+ the filename, and may not get it right for
+ .emacs.
+
+
+
+ The tab key is bound to an
+ indentation function in some modes, so when you press the
+ tab key, it will indent the current line of code. If you
+ want to put a tab character in whatever
+ you're writing, hold the control key down
+ while you're pressing the tab key.
+
+
+
+ This file supports syntax highlighting for C, C++,
+ Perl, Lisp and Scheme, by guessing the language from the
+ filename.
+
+
+
+ Emacs already has a pre-defined function called
+ next-error. In a compilation output
+ window, this allows you to move from one compilation error
+ to the next by doing M-n; we define a
+ complementary function,
+ previous-error, that allows you to go
+ to a previous error by doing M-p. The
+ nicest feature of all is that C-c C-c
+ will open up the source file in which the error occurred
+ and jump to the appropriate line.
+
+
+
+ We enable Emacs's ability to act as a server, so that
+ if you're doing something outside Emacs and you want to
+ edit a file, you can just type in
+
+ &prompt.user; emacsclient filename
+
+
+ and then you can edit the file in your
+ Emacs!
+
+
+ Many Emacs users set their EDITOR environment to
+ emacsclient so this happens every
+ time they need to edit a file.
+
+
+
+
+
+ A sample <filename>.emacs</filename> file
+
+ ;; -*-Emacs-Lisp-*-
+
+;; This file is designed to be re-evaled; use the variable first-time
+;; to avoid any problems with this.
+(defvar first-time t
+ "Flag signifying this is the first time that .emacs has been evaled")
+
+;; Meta
+(global-set-key "\M- " 'set-mark-command)
+(global-set-key "\M-\C-h" 'backward-kill-word)
+(global-set-key "\M-\C-r" 'query-replace)
+(global-set-key "\M-r" 'replace-string)
+(global-set-key "\M-g" 'goto-line)
+(global-set-key "\M-h" 'help-command)
+
+;; Function keys
+(global-set-key [f1] 'manual-entry)
+(global-set-key [f2] 'info)
+(global-set-key [f3] 'repeat-complex-command)
+(global-set-key [f4] 'advertised-undo)
+(global-set-key [f5] 'eval-current-buffer)
+(global-set-key [f6] 'buffer-menu)
+(global-set-key [f7] 'other-window)
+(global-set-key [f8] 'find-file)
+(global-set-key [f9] 'save-buffer)
+(global-set-key [f10] 'next-error)
+(global-set-key [f11] 'compile)
+(global-set-key [f12] 'grep)
+(global-set-key [C-f1] 'compile)
+(global-set-key [C-f2] 'grep)
+(global-set-key [C-f3] 'next-error)
+(global-set-key [C-f4] 'previous-error)
+(global-set-key [C-f5] 'display-faces)
+(global-set-key [C-f8] 'dired)
+(global-set-key [C-f10] 'kill-compilation)
+
+;; Keypad bindings
+(global-set-key [up] "\C-p")
+(global-set-key [down] "\C-n")
+(global-set-key [left] "\C-b")
+(global-set-key [right] "\C-f")
+(global-set-key [home] "\C-a")
+(global-set-key [end] "\C-e")
+(global-set-key [prior] "\M-v")
+(global-set-key [next] "\C-v")
+(global-set-key [C-up] "\M-\C-b")
+(global-set-key [C-down] "\M-\C-f")
+(global-set-key [C-left] "\M-b")
+(global-set-key [C-right] "\M-f")
+(global-set-key [C-home] "\M-<")
+(global-set-key [C-end] "\M->")
+(global-set-key [C-prior] "\M-<")
+(global-set-key [C-next] "\M->")
+
+;; Mouse
+(global-set-key [mouse-3] 'imenu)
+
+;; Misc
+(global-set-key [C-tab] "\C-q\t") ; Control tab quotes a tab.
+(setq backup-by-copying-when-mismatch t)
+
+;; Treat 'y' or <CR> as yes, 'n' as no.
+(fset 'yes-or-no-p 'y-or-n-p)
+ (define-key query-replace-map [return] 'act)
+ (define-key query-replace-map [?\C-m] 'act)
+
+;; Load packages
+(require 'desktop)
+(require 'tar-mode)
+
+;; Pretty diff mode
+(autoload 'ediff-buffers "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files "ediff" "Intelligent Emacs interface to diff" t)
+(autoload 'ediff-files-remote "ediff"
+ "Intelligent Emacs interface to diff")
+
+(if first-time
+ (setq auto-mode-alist
+ (append '(("\\.cpp$" . c++-mode)
+ ("\\.hpp$" . c++-mode)
+ ("\\.lsp$" . lisp-mode)
+ ("\\.scm$" . scheme-mode)
+ ("\\.pl$" . perl-mode)
+ ) auto-mode-alist)))
+
+;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+(defvar font-lock-mode-keyword-alist
+ '((c++-c-mode . c-font-lock-keywords)
+ (perl-mode . perl-font-lock-keywords))
+ "Associations between modes and keywords")
+
+(defun font-lock-auto-mode-select ()
+ "Automatically select font-lock-mode if the current major mode is
+in font-lock-auto-mode-list"
+ (if (memq major-mode font-lock-auto-mode-list)
+ (progn
+ (font-lock-mode t))
+ )
+ )
+
+(global-set-key [M-f1] 'font-lock-fontify-buffer)
+
+;; New dabbrev stuff
+;(require 'new-dabbrev)
+(setq dabbrev-always-check-other-buffers t)
+(setq dabbrev-abbrev-char-regexp "\\sw\\|\\s_")
+(add-hook 'emacs-lisp-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'c-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) nil)
+ (set (make-local-variable 'dabbrev-case-replace) nil)))
+(add-hook 'text-mode-hook
+ '(lambda ()
+ (set (make-local-variable 'dabbrev-case-fold-search) t)
+ (set (make-local-variable 'dabbrev-case-replace) t)))
+
+;; C++ and C mode...
+(defun my-c++-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c++-mode-map "\C-ce" 'c-comment-edit)
+ (setq c++-auto-hungry-initial-state 'none)
+ (setq c++-delete-function 'backward-delete-char)
+ (setq c++-tab-always-indent t)
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c++-empty-arglist-indent 4))
+
+(defun my-c-mode-hook ()
+ (setq tab-width 4)
+ (define-key c-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key c-mode-map "\C-ce" 'c-comment-edit)
+ (setq c-auto-hungry-initial-state 'none)
+ (setq c-delete-function 'backward-delete-char)
+ (setq c-tab-always-indent t)
+;; BSD-ish indentation style
+ (setq c-indent-level 4)
+ (setq c-continued-statement-offset 4)
+ (setq c-brace-offset -4)
+ (setq c-argdecl-indent 0)
+ (setq c-label-offset -4))
+
+;; Perl mode
+(defun my-perl-mode-hook ()
+ (setq tab-width 4)
+ (define-key c++-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (setq perl-indent-level 4)
+ (setq perl-continued-statement-offset 4))
+
+;; Scheme mode...
+(defun my-scheme-mode-hook ()
+ (define-key scheme-mode-map "\C-m" 'reindent-then-newline-and-indent))
+
+;; Emacs-Lisp mode...
+(defun my-lisp-mode-hook ()
+ (define-key lisp-mode-map "\C-m" 'reindent-then-newline-and-indent)
+ (define-key lisp-mode-map "\C-i" 'lisp-indent-line)
+ (define-key lisp-mode-map "\C-j" 'eval-print-last-sexp))
+
+;; Add all of the hooks...
+(add-hook 'c++-mode-hook 'my-c++-mode-hook)
+(add-hook 'c-mode-hook 'my-c-mode-hook)
+(add-hook 'scheme-mode-hook 'my-scheme-mode-hook)
+(add-hook 'emacs-lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'lisp-mode-hook 'my-lisp-mode-hook)
+(add-hook 'perl-mode-hook 'my-perl-mode-hook)
+
+;; Complement to next-error
+(defun previous-error (n)
+ "Visit previous compilation error message and corresponding source code."
+ (interactive "p")
+ (next-error (- n)))
+
+;; Misc...
+(transient-mark-mode 1)
+(setq mark-even-if-inactive t)
+(setq visible-bell nil)
+(setq next-line-add-newlines nil)
+(setq compile-command "make")
+(setq suggest-key-bindings nil)
+(put 'eval-expression 'disabled nil)
+(put 'narrow-to-region 'disabled nil)
+(put 'set-goal-column 'disabled nil)
+
+;; Elisp archive searching
+(autoload 'format-lisp-code-directory "lispdir" nil t)
+(autoload 'lisp-dir-apropos "lispdir" nil t)
+(autoload 'lisp-dir-retrieve "lispdir" nil t)
+(autoload 'lisp-dir-verify "lispdir" nil t)
+
+;; Font lock mode
+(defun my-make-face (face colour &optional bold)
+ "Create a face from a colour and optionally make it bold"
+ (make-face face)
+ (copy-face 'default face)
+ (set-face-foreground face colour)
+ (if bold (make-face-bold face))
+ )
+
+(if (eq window-system 'x)
+ (progn
+ (my-make-face 'blue "blue")
+ (my-make-face 'red "red")
+ (my-make-face 'green "dark green")
+ (setq font-lock-comment-face 'blue)
+ (setq font-lock-string-face 'bold)
+ (setq font-lock-type-face 'bold)
+ (setq font-lock-keyword-face 'bold)
+ (setq font-lock-function-name-face 'red)
+ (setq font-lock-doc-string-face 'green)
+ (add-hook 'find-file-hooks 'font-lock-auto-mode-select)
+
+ (setq baud-rate 1000000)
+ (global-set-key "\C-cmm" 'menu-bar-mode)
+ (global-set-key "\C-cms" 'scroll-bar-mode)
+ (global-set-key [backspace] 'backward-delete-char)
+ ; (global-set-key [delete] 'delete-char)
+ (standard-display-european t)
+ (load-library "iso-transl")))
+
+;; X11 or PC using direct screen writes
+(if window-system
+ (progn
+ ;; (global-set-key [M-f1] 'hilit-repaint-command)
+ ;; (global-set-key [M-f2] [?\C-u M-f1])
+ (setq hilit-mode-enable-list
+ '(not text-mode c-mode c++-mode emacs-lisp-mode lisp-mode
+ scheme-mode)
+ hilit-auto-highlight nil
+ hilit-auto-rehighlight 'visible
+ hilit-inhibit-hooks nil
+ hilit-inhibit-rebinding t)
+ (require 'hilit19)
+ (require 'paren))
+ (setq baud-rate 2400) ; For slow serial connections
+ )
+
+;; TTY type terminal
+(if (and (not window-system)
+ (not (equal system-type 'ms-dos)))
+ (progn
+ (if first-time
+ (progn
+ (keyboard-translate ?\C-h ?\C-?)
+ (keyboard-translate ?\C-? ?\C-h)))))
+
+;; Under UNIX
+(if (not (equal system-type 'ms-dos))
+ (progn
+ (if first-time
+ (server-start))))
+
+;; Add any face changes here
+(add-hook 'term-setup-hook 'my-term-setup-hook)
+(defun my-term-setup-hook ()
+ (if (eq window-system 'pc)
+ (progn
+;; (set-face-background 'default "red")
+ )))
+
+;; Restore the "desktop" - do this as late as possible
+(if first-time
+ (progn
+ (desktop-load-default)
+ (desktop-read)))
+
+;; Indicate that this file has been read at least once
+(setq first-time nil)
+
+;; No need to debug anything now
+(setq debug-on-error nil)
+
+;; All done
+(message "All done, %s%s" (user-login-name) ".")
+
+
+
+
+
+ Extending the Range of Languages Emacs Understands
+
+ Now, this is all very well if you only want to program in
+ the languages already catered for in the
+ .emacs file (C, C++, Perl, Lisp and
+ Scheme), but what happens if a new language called
+ whizbang comes out, full of exciting
+ features?
+
+ The first thing to do is find out if whizbang comes with
+ any files that tell Emacs about the language. These usually
+ end in .el, short for Emacs
+ Lisp. For example, if whizbang is a FreeBSD port, we
+ can locate these files by doing
+
+ &prompt.user; find /usr/ports/lang/whizbang -name "*.el" -print
+
+
+ and install them by copying them into the Emacs site Lisp
+ directory. On FreeBSD 2.1.0-RELEASE, this is
+ /usr/local/share/emacs/site-lisp.
+
+ So for example, if the output from the find command
+ was
+
+ /usr/ports/lang/whizbang/work/misc/whizbang.el
+
+
+ we would do
+
+ &prompt.root; cp /usr/ports/lang/whizbang/work/misc/whizbang.el /usr/local/share/emacs/site-lisp
+
+
+ Next, we need to decide what extension whizbang source
+ files have. Let's say for the sake of argument that they all
+ end in .wiz. We need to add an entry to
+ our .emacs file to make sure Emacs will
+ be able to use the information in
+ whizbang.el.
+
+ Find the auto-mode-alist entry in
+ .emacs and add a line for whizbang, such
+ as:
+
+ …
+("\\.lsp$" . lisp-mode)
+("\\.wiz$" . whizbang-mode)
+("\\.scm$" . scheme-mode)
+…
+
+
+ This means that Emacs will automatically go into
+ whizbang-mode when you edit a file ending
+ in .wiz.
+
+ Just below this, you'll find the
+ font-lock-auto-mode-list entry. Add
+ whizbang-mode to it like so:
+
+ ;; Auto font lock mode
+(defvar font-lock-auto-mode-list
+ (list 'c-mode 'c++-mode 'c++-c-mode 'emacs-lisp-mode 'whizbang-mode 'lisp-mode 'perl-mode 'scheme-mode)
+ "List of modes to always start in font-lock-mode")
+
+
+ This means that Emacs will always enable
+ font-lock-mode (ie syntax highlighting)
+ when editing a .wiz file.
+
+ And that's all that's needed. If there's anything else
+ you want done automatically when you open up a
+ .wiz file, you can add a
+ whizbang-mode hook (see
+ my-scheme-mode-hook for a simple example
+ that adds auto-indent).
+
+
+
+
+ Further Reading
+
+
+
+ Brian Harvey and Matthew Wright
+ Simply Scheme
+ MIT 1994.
+ ISBN 0-262-08226-8
+
+
+
+ Randall Schwartz
+ Learning Perl
+ O'Reilly 1993
+ ISBN 1-56592-042-2
+
+
+
+ Patrick Henry Winston and Berthold Klaus Paul Horn
+ Lisp (3rd Edition)
+ Addison-Wesley 1989
+ ISBN 0-201-08319-1
+
+
+
+ Brian W. Kernighan and Rob Pike
+ The Unix Programming Environment
+ Prentice-Hall 1984
+ ISBN 0-13-937681-X
+
+
+
+ Brian W. Kernighan and Dennis M. Ritchie
+ The C Programming Language (2nd Edition)
+ Prentice-Hall 1988
+ ISBN 0-13-110362-8
+
+
+
+ Bjarne Stroustrup
+ The C++ Programming Language
+ Addison-Wesley 1991
+ ISBN 0-201-53992-6
+
+
+
+ W. Richard Stevens
+ Advanced Programming in the Unix Environment
+ Addison-Wesley 1992
+ ISBN 0-201-56317-7
+
+
+
+ W. Richard Stevens
+ Unix Network Programming
+ Prentice-Hall 1990
+ ISBN 0-13-949876-1
+
+
+
-
@@ -1357,7 +3598,7 @@ DRIVER_MODULE(mypci, pci, mypci_driver, mypci_devclass, 0, 0);
-
+ Debugging