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<!--
The FreeBSD Documentation Project
$FreeBSD: doc/en_US.ISO_8859-1/books/handbook/basics/chapter.sgml,v 1.12 1999/11/07 01:54:43 chris Exp $
$FreeBSD: doc/en_US.ISO_8859-1/books/handbook/basics/chapter.sgml,v 1.13 2000/01/24 20:54:53 jim Exp $
-->
<chapter id="basics">
<title>Unix Basics</title>
<sect1 id="basics-man">
<title>The Online Manual</title>
<para>The most comprehensive documentation on FreeBSD is in the form of
<emphasis>man pages</emphasis>. Nearly every program on the system
comes with a short reference manual explaining the basic operation and
various arguments. These manuals can be viewed with the
<command>man</command> command. Use of the <command>man</command>
command is simple:</para>
<screen>&prompt.user; <userinput>man <replaceable>command</replaceable></userinput></screen>
<sect1>
<title>Synopsis</title>
<para><replaceable>command</replaceable> is the name of the command you
wish to learn about. For example, to learn more about
<command>ls</command> command type:</para>
<screen>&prompt.user; <userinput>man ls</userinput></screen>
<para>The online manual is divided up into numbered sections:</para>
<orderedlist>
<listitem>
<para>User commands</para>
</listitem>
<listitem>
<para>System calls and error numbers</para>
</listitem>
<listitem>
<para>Functions in the C libraries</para>
</listitem>
<listitem>
<para>Device drivers</para>
</listitem>
<listitem>
<para>File formats</para>
</listitem>
<listitem>
<para>Games and other diversions</para>
</listitem>
<listitem>
<para>Miscellaneous information</para>
</listitem>
<listitem>
<para>System maintenance and operation commands</para>
</listitem>
<para><emphasis>Reritten by Chris Schumway
<email>cshumway@cdrom.com</email>, 10 Mar 2000.</emphasis></para>
<listitem>
<para>Kernel developers</para>
</listitem>
</orderedlist>
<para>In some cases, the same topic may appear in more than one section of
the on-line manual. For example, there is a <command>chmod</command>
user command and a <function>chmod()</function> system call. In this
case, you can tell the <command>man</command> command which one you want
by specifying the section:</para>
<screen>&prompt.user; <userinput>man 1 chmod</userinput></screen>
<para>This will display the manual page for the user command
<command>chmod</command>. References to a particular section of the
on-line manual are traditionally placed in parenthesis in written
documentation, so &man.chmod.1; refers to the
<command>chmod</command> user command and &man.chmod.2; refers to the
system call.</para>
<para>This is fine if you know the name of the command and simply wish to
know how to use it, but what if you cannot recall the command name? You
can use <command>man</command> to search for keywords in the command
<emphasis>descriptions</emphasis> by using the <option>-k</option>
switch:</para>
<screen>&prompt.user; <userinput>man -k mail</userinput></screen>
<para>With this command you will be presented with a list of commands that
have the keyword &ldquo;mail&rdquo; in their descriptions. This is
actually functionally equivalent to using the <command>apropos</command>
command.</para>
<para>So, you are looking at all those fancy commands in
<filename>/usr/bin</filename> but do not have the faintest idea
what most of them actually do? Simply do a
<screen>&prompt.user; <userinput>cd /usr/bin; man -f *</userinput></screen>
or
<screen>&prompt.user; <userinput>cd /usr/bin; whatis *</userinput></screen>
which does the same thing.</para>
<para>The following chapter will cover the basic commands and
functionality of the FreeBSD operating system. If you are new to
FreeBSD, you will definitely want to read through this chapter before
asking for help.</para>
</sect1>
<sect1 id="basics-info">
<title>GNU Info Files</title>
<para>FreeBSD includes many applications and utilities produced by the
Free Software Foundation (FSF). In addition to man pages, these
programs come with more extensive hypertext documents called
&ldquo;info&rdquo; files which can be viewed with the
<command>info</command> command or, if you installed
<command>emacs</command>, the info mode of
<command>emacs</command>.</para>
<para>To use the &man.info.1; command, simply type:</para>
<screen>&prompt.user; <userinput>info</userinput></screen>
<para>For a brief introduction, type <userinput>h</userinput>. For a
quick command reference, type <userinput>?</userinput>.</para>
<sect1 id="permissions">
<title>Permissions</title>
<para>FreeBSD, having its history rooted in BSD UNIX, has its
fundamentals based on several key UNIX concepts. The first, and
most pronounced, is that FreeBSD is a multi-user operating system.
The system can handle several users all working simultaneously on
completely unrelated tasks. The system is responsible for properly
sharing and managing requests for hardware devices, preferials,
memory, and cpu time evenly to each user.</para>
<para>Because the system is capable of supporting multiple users,
everything the system manages has a set of permissions governing who
can read, write, and execute the resource. These permissions are
stored as an octet broken into three pieces, one for the owner of
the file, one for the group that the file belongs to, and one for
everyone else. This numerical representation works like
this:</para>
<informaltable frame="none">
<tgroup cols="3">
<thead>
<row>
<entry>Value</entry>
<entry>Permission</entry>
<entry>Directory Listing</entry>
</row>
</thead>
<tbody>
<row>
<entry>0</entry>
<entry>No read, no write, no execute</entry>
<entry><literal>---</literal></entry>
</row>
<row>
<entry>1</entry>
<entry>No read, no write, execute</entry>
<entry><literal>--x</literal></entry>
</row>
<row>
<entry>2</entry>
<entry>No read, write, no execute</entry>
<entry><literal>-w-</literal></entry>
</row>
<row>
<entry>3</entry>
<entry>No read, write, execute</entry>
<entry><literal>-wx</literal></entry>
</row>
<row>
<entry>4</entry>
<entry>Read, no write, no execute</entry>
<entry><literal>r--</literal></entry>
</row>
<row>
<entry>5</entry>
<entry>Read, no write, execute</entry>
<entry><literal>r-x</literal></entry>
</row>
<row>
<entry>6</entry>
<entry>Read, write, no execute</entry>
<entry><literal>rw-</literal></entry>
</row>
<row>
<entry>7</entry>
<entry>Read, write, execute</entry>
<entry><literal>rwx</literal></entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>For the long directory listing by <command>ls -l</command>, a
column will show a files' permissions for the owner, group, and
everyone else. Here's how its broken up:</para>
<screen>-rw-r--r--</screen>
<para>The first character, from left to right, is a special character
that tells if this is a regular file, a directory, a special
character or block device, a socket, or any other special
pseudo-file device. The next three characters, designated as
<literal>rw-</literal> gives the permissions for the owner of the
file. The next three characters, <literal>r--</literal> gives the
permissions for the group that the file belongs to. The final three
characters, <literal>r--</literal>, gives the permissions for the
rest of the world. A dash means that the permission is turned off.
In the case of this file, the permissions are set so the owner can
read and write to the file, the group can read the file, and the
rest of the world can only read the file. According to the table
above, the permissions for this file would be
<literal>644</literal>, where each digit represents the three parts
of the file's permission.</para>
<para>This is all well and good files, but how does the system control
permissions on devices? FreeBSD actually treats most hardware
devices as a file that programs can open, read, and write data to
just like any other file. These special device files are stored on
the <filename>/dev</filename> directory.</para>
<para>Directories are also treated as files. They have read, write,
and execute permissions. The executable bit for a directory has a
slightly different meaning than that of files. When a directory is
marked executable, it means it can be searched into, for example, a
directory listing can be done in that directory.</para>
<para>There are more to permissions, but they are primarily used in
special circumstances such as setuid binaries and sticky
directories. If you want more information on file permissions and
how to set them, be sure to look at the &man.chmod.1; man
page.</para>
</sect1>
<sect1 id="dirstructure">
<title>Directory Structures</title>
<para>Since FreeBSD uses its file systems to determine many
fundamental system operations, the hiarchy of the file system is
extremely important. Due to the fact that the &man.hier.7; man page
provides a complete description of the directory structure, it will
not be duplicated here. Please read &man.hier.7; for more
information.</para>
<para>Of significant importance is the root of all directories, the /
directory. This directory is the first directory mounted at boot
time and it contains the base system necessary at boot time. The
root directory also contains mount points for every other file
system that you want to mount.</para>
<para>A mount point is a directory where additional file systems can
be grafted onto the root file system. Standard mount points include
<filename>/usr</filename>, <filename>/var</filename>,
<filename>/mnt</filename>, and <filename>/cdrom</filename>. These
directories are usually referenced to entries in the file
<filename>/etc/fstab</filename>. <filename>/etc/fstab</filename> is
a table of various file systems and mount points for refence by the
system. Most of the file systems in <filename>/etc/fstab</filename>
are mounted automatically at boot time from the script &man.rc.8;
unless they contain the noauto option. Consult the &man.fstab.5;
manual page for more information on the format of the
<filename>/etc/fstab</filename> file and the options it
contains.</para>
</sect1>
<sect1 id="shells">
<title>Shells</title>
<para>In FreeBSD, a lot of everyday work is done in a command line
interface called a shell. A shell's main job is to take commands
from the input channel and execute them. A lot of shells also have
built in functions to help everyday tasks such a file management,
file globing, command line editing, command mar-cos, and environment
variables. FreeBSD comes with a set of shells, such as sh, the
Bourne Shell, and csh, the C-shell. Many other shells are available
from the FreeBSD Ports Collection that have much more power, such as
tcsh and bash.</para>
<para>Which shell do you use? Its really a matter of taste. If your
a C programmer you might feel more comfortable with a C-like shell
such as tcsh. If you've come from Linux or are new to a UNIX
command line interface you might try bash. The point is that each
shell has unique properties that may or may not work with your
preferred working environment, and that you have a choice of what
shell to use.</para>
<para>One common feature in a shell is file-name completion. Given
the typing of the first few letters of a command or filename, you
can usually have the shell automatically complete the rest of the
command or filename by hitting the TAB key on the keyboard. Here is
an example. I have two files called <filename>foobar</filename> and
<filename>foo.bar</filename>. I want to delete
<filename>foo.bar</filename>. So what I would type on the keyboard
is: <command>rm fo[TAB].[TAB]</command>.</para>
<para>The shell would print out <command>rm
foo[BEEP].bar</command>.</para>
<para>The [BEEP] is the console bell, which is the shell telling me it
was unable to totally complete the filename because there is more
than one match. Both <filename>foobar</filename> and
<filename>foo.bar</filename> start with <literal>fo</literal>, but
it was able to complete to <literal>foo</literal>. Once I typed in
<literal>.</literal>, then hit TAB again, the shell was able to fill
in the rest of the filename for me.</para>
<para>Another function of the shell is environment variables.
Environment variables are a variable key pair stored in the shell's
environment space. This space can be read by any program invoked by
the shell, and thus contains a lot of program configuration. Here
is a list of common environment variables and what they mean:</para>
<informaltable frame="none">
<tgroup cols="2">
<thead>
<row>
<entry>Variable</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><envar>USER</envar></entry>
<entry>Current logged in user's name.</entry>
</row>
<row>
<entry><envar>PATH</envar></entry>
<entry>Colon separated list of directories to search for
binaries.</entry>
</row>
<row>
<entry><envar>DISPLAY</envar></entry>
<entry>Network name of the X11 display to connect to, if
available.</entry>
</row>
<row>
<entry><envar>SHELL</envar></entry>
<entry>The current shell.</entry>
</row>
<row>
<entry><envar>TERM</envar></entry>
<entry>The name of the user's terminal. Used to determine the
capabilites of the terminal.</entry>
</row>
<row>
<entry><envar>TERMCAP</envar></entry>
<entry>Database entry of the terminal escape codes to perform
various terminal functions.</entry>
</row>
<row>
<entry><envar>OSTYPE</envar></entry>
<entry>Type of operating system. E.g., FreeBSD.</entry>
</row>
<row>
<entry><envar>MACHTYPE</envar></entry>
<entry>The CPU architecture that the system is running
on.</entry>
</row>
<row>
<entry><envar>EDITOR</envar></entry>
<entry>The user's preferred text editor.</entry>
</row>
<row>
<entry><envar>PAGER</envar></entry>
<entry>The user's preferred text pager.</entry>
</row>
<row>
<entry><envar>MANPATH</envar></entry>
<entry>Colon separated list of directories to search for
manual pages.</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>To view or set an environment variable differs somewhat from
shell to shell. For example, in the C-Style shells such as tcsh
and csh, you would use <command>setenv</command> to set and view
environment variables. Under Bourne shells such as sh and bash, you
would use <command>set</command> and <command>export</command> to
view and set your current environment variables. For example, to
set or modify the <envar>EDITOR</envar> environment variable, under
csh or tcsh a command like this would set <envar>EDITOR</envar> to
<filename>/usr/local/bin/emacs</filename>:</para>
<para><command>setenv EDITOR /usr/local/bin/emacs</command></para>
<para>Under Bourne shells:</para>
<para><command>export EDITOR="/usr/local/bin/emacs"</command></para>
<para>You can also make most shells expand the environment variable by
placing a <literal>$</literal> character in front of it on the
command line. For example, <command>echo $TERM</command> would
print out whatever <envar>$TERM</envar> is set to, because the shell
expands <envar>$TERM</envar> and passes it on to echo.</para>
<para>Shells treat a lot of special characters, called meta-characters
as special representations of data. The most common one is the
<literal>*</literal> character, which represents any number of
characters in a filename. These special meta-characters can be used
to do file name globing. For example, typing in
<command>echo *</command> is almost the same as typing in
<command>ls</command> because the shell takes all the files that
match <command>*</command> and puts them on the command line for
echo to see.</para>
<para>To prevent the shell from interpreting these special characters,
they can be escaped from the shell by putting a backslash
(<literal>\</literal>) character in front of them. <command>echo
$TERM</command> prints whatever your terminal is set to.
<command>echo \$TERM</command> prints <envar>$TERM</envar> as
is.</para>
</sect1>
<sect1 id="editors">
<title>Text Editors</title>
<para>A lot of configuration in FreeBSD is done by editing a text
file. Because of this, it would be a good idea to become familiar
with a text editor. FreeBSD comes with a few as part of the base
system, and many more are available in the ports collection.</para>
<para>The easiest and simplest editor to learn is an editor called
<application>ee</application>, which stands for easy editor. To
start <application>ee</application>, one would type at the command
line <command>ee filename</command> where
<literal>filename</literal> is the name of the file to be edited.
For example, to edit <filename>/etc/rc.conf</filename>, type in
<command>ee /etc/rc.conf</command>. Once inside of ee, all of the
commands for manipulating the editor's functions are listed at the
top of the display. The caret <literal>^</literal> character means
the control key on the keyboard, so ^e expands to pressing the
control key plus the letter <literal>e</literal>. To leave
<application>ee</application>, hit the escape key, then choose leave
editor. The editor will prompt you to save any changes if the file
has been modified.</para>
<para>FreeBSD also comes with more powerful text editors such as
<application>vi</application> as part of the base system, and
<application>emacs</application> and <application>vim</application>
as part of the FreeBSD ports collection. These editors offer much
more functionality and power at the expense of being a little more
complicated to learn. However if you plan on doing a lot of text
editing, learning a more powerful editor such as
<application>vim</application> or <application>emacs</application>
will save you much more time in the long run.</para>
</sect1>
<sect1>
<title>For more information...</title>
<sect2 id="basics-man">
<title>Manual pages</title>
<para>The most comprehensive documentation on FreeBSD is in the form
of man pages. Nearly every program on the system comes with a
short reference manual explaining the basic operation and various
arguments. These manuals can be viewed with the man command. Use
of the man command is simple:</para>
<para><command>&prompt.user; man command</command></para>
<para><literal>command</literal> is the name of the command you
wish to learn about. For example, to learn more about
<command>ls</command> command type:</para>
<para><command>&prompt.user; man ls</command></para>
<para>The online manual is divided up into numbered sections:</para>
<orderedlist>
<listitem>
<para>User commands.</para>
</listitem>
<listitem>
<para>System calls and error numbers.</para>
</listitem>
<listitem>
<para>Functions in the C libraries.</para>
</listitem>
<listitem>
<para>Device drivers.</para>
</listitem>
<listitem>
<para>File formats.</para>
</listitem>
<listitem>
<para>Games and other diversions.</para>
</listitem>
<listitem>
<para>Miscellaneous information.</para>
</listitem>
<listitem>
<para>System maintenance and operation commands.</para>
</listitem>
<listitem>
<para>Kernel developers.</para>
</listitem>
</orderedlist>
<para>In some cases, the same topic may appear in more than one
section of the online manual. For example, there is a chmod user
command and a <literal>chmod()</literal> system call. In this
case, you can tell the man command which one you want by
specifying the section:</para>
<para><command>&prompt.user; man 1 chmod</command></para>
<para>This will display the manual page for the user command
<command>chmod</command>. References to a particular section of
the online manual are traditionally placed in parenthesis in
written documentation, so &man.chmod.1; refers to the
<command>chmod</command> user command and &man.chmod.2; refers to
the system call.</para>
<para>This is fine if you know the name of the command and simply
wish to know how to use it, but what if you cannot recall the
command name? You can use man to search for keywords in the
command descriptions by using the <option>-k</option>
switch:</para>
<para><command>&prompt.user; man -k mail</command></para>
<para>With this command you will be presented with a list of
commands that have the keyword &ldquo;mail&rdquo; in their
descriptions. This is actually functionally equivalent to using
the apropos command.</para>
<para>So, you are looking at all those fancy commands in
<filename>/usr/bin</filename> but do not have the faintest idea
what most of them actually do? Simply do a
<command>&prompt.user; cd /usr/bin; man -f *</command> or
<command>&prompt.user; cd /usr/bin; whatis *</command> which
does the same thing.</para>
</sect2>
<sect2 id="basics-info">
<title>GNU Info Files</title>
<para>FreeBSD includes many applications and utilities produced by
the Free Software Foundation (FSF). In addition to man pages,
these programs come with more extensive hypertext documents called
<literal>info</literal> files which can be viewed with the
<command>info</command> command or, if you installed
<application>emacs</application>, the info mode of
<application>emacs</application>.</para>
<para>To use the &man.info.1; command, simply type:</para>
<para><command>&prompt.user; info</command></para>
<para>For a brief introduction, type <literal>h</literal>. For a
quick command reference, type <literal>?</literal>.</para>
</sect2>
</sect1>
</chapter>
<!--
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<!--
The FreeBSD Documentation Project
$FreeBSD: doc/en_US.ISO_8859-1/books/handbook/basics/chapter.sgml,v 1.12 1999/11/07 01:54:43 chris Exp $
$FreeBSD: doc/en_US.ISO_8859-1/books/handbook/basics/chapter.sgml,v 1.13 2000/01/24 20:54:53 jim Exp $
-->
<chapter id="basics">
<title>Unix Basics</title>
<sect1 id="basics-man">
<title>The Online Manual</title>
<para>The most comprehensive documentation on FreeBSD is in the form of
<emphasis>man pages</emphasis>. Nearly every program on the system
comes with a short reference manual explaining the basic operation and
various arguments. These manuals can be viewed with the
<command>man</command> command. Use of the <command>man</command>
command is simple:</para>
<screen>&prompt.user; <userinput>man <replaceable>command</replaceable></userinput></screen>
<sect1>
<title>Synopsis</title>
<para><replaceable>command</replaceable> is the name of the command you
wish to learn about. For example, to learn more about
<command>ls</command> command type:</para>
<screen>&prompt.user; <userinput>man ls</userinput></screen>
<para>The online manual is divided up into numbered sections:</para>
<orderedlist>
<listitem>
<para>User commands</para>
</listitem>
<listitem>
<para>System calls and error numbers</para>
</listitem>
<listitem>
<para>Functions in the C libraries</para>
</listitem>
<listitem>
<para>Device drivers</para>
</listitem>
<listitem>
<para>File formats</para>
</listitem>
<listitem>
<para>Games and other diversions</para>
</listitem>
<listitem>
<para>Miscellaneous information</para>
</listitem>
<listitem>
<para>System maintenance and operation commands</para>
</listitem>
<para><emphasis>Reritten by Chris Schumway
<email>cshumway@cdrom.com</email>, 10 Mar 2000.</emphasis></para>
<listitem>
<para>Kernel developers</para>
</listitem>
</orderedlist>
<para>In some cases, the same topic may appear in more than one section of
the on-line manual. For example, there is a <command>chmod</command>
user command and a <function>chmod()</function> system call. In this
case, you can tell the <command>man</command> command which one you want
by specifying the section:</para>
<screen>&prompt.user; <userinput>man 1 chmod</userinput></screen>
<para>This will display the manual page for the user command
<command>chmod</command>. References to a particular section of the
on-line manual are traditionally placed in parenthesis in written
documentation, so &man.chmod.1; refers to the
<command>chmod</command> user command and &man.chmod.2; refers to the
system call.</para>
<para>This is fine if you know the name of the command and simply wish to
know how to use it, but what if you cannot recall the command name? You
can use <command>man</command> to search for keywords in the command
<emphasis>descriptions</emphasis> by using the <option>-k</option>
switch:</para>
<screen>&prompt.user; <userinput>man -k mail</userinput></screen>
<para>With this command you will be presented with a list of commands that
have the keyword &ldquo;mail&rdquo; in their descriptions. This is
actually functionally equivalent to using the <command>apropos</command>
command.</para>
<para>So, you are looking at all those fancy commands in
<filename>/usr/bin</filename> but do not have the faintest idea
what most of them actually do? Simply do a
<screen>&prompt.user; <userinput>cd /usr/bin; man -f *</userinput></screen>
or
<screen>&prompt.user; <userinput>cd /usr/bin; whatis *</userinput></screen>
which does the same thing.</para>
<para>The following chapter will cover the basic commands and
functionality of the FreeBSD operating system. If you are new to
FreeBSD, you will definitely want to read through this chapter before
asking for help.</para>
</sect1>
<sect1 id="basics-info">
<title>GNU Info Files</title>
<para>FreeBSD includes many applications and utilities produced by the
Free Software Foundation (FSF). In addition to man pages, these
programs come with more extensive hypertext documents called
&ldquo;info&rdquo; files which can be viewed with the
<command>info</command> command or, if you installed
<command>emacs</command>, the info mode of
<command>emacs</command>.</para>
<para>To use the &man.info.1; command, simply type:</para>
<screen>&prompt.user; <userinput>info</userinput></screen>
<para>For a brief introduction, type <userinput>h</userinput>. For a
quick command reference, type <userinput>?</userinput>.</para>
<sect1 id="permissions">
<title>Permissions</title>
<para>FreeBSD, having its history rooted in BSD UNIX, has its
fundamentals based on several key UNIX concepts. The first, and
most pronounced, is that FreeBSD is a multi-user operating system.
The system can handle several users all working simultaneously on
completely unrelated tasks. The system is responsible for properly
sharing and managing requests for hardware devices, preferials,
memory, and cpu time evenly to each user.</para>
<para>Because the system is capable of supporting multiple users,
everything the system manages has a set of permissions governing who
can read, write, and execute the resource. These permissions are
stored as an octet broken into three pieces, one for the owner of
the file, one for the group that the file belongs to, and one for
everyone else. This numerical representation works like
this:</para>
<informaltable frame="none">
<tgroup cols="3">
<thead>
<row>
<entry>Value</entry>
<entry>Permission</entry>
<entry>Directory Listing</entry>
</row>
</thead>
<tbody>
<row>
<entry>0</entry>
<entry>No read, no write, no execute</entry>
<entry><literal>---</literal></entry>
</row>
<row>
<entry>1</entry>
<entry>No read, no write, execute</entry>
<entry><literal>--x</literal></entry>
</row>
<row>
<entry>2</entry>
<entry>No read, write, no execute</entry>
<entry><literal>-w-</literal></entry>
</row>
<row>
<entry>3</entry>
<entry>No read, write, execute</entry>
<entry><literal>-wx</literal></entry>
</row>
<row>
<entry>4</entry>
<entry>Read, no write, no execute</entry>
<entry><literal>r--</literal></entry>
</row>
<row>
<entry>5</entry>
<entry>Read, no write, execute</entry>
<entry><literal>r-x</literal></entry>
</row>
<row>
<entry>6</entry>
<entry>Read, write, no execute</entry>
<entry><literal>rw-</literal></entry>
</row>
<row>
<entry>7</entry>
<entry>Read, write, execute</entry>
<entry><literal>rwx</literal></entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>For the long directory listing by <command>ls -l</command>, a
column will show a files' permissions for the owner, group, and
everyone else. Here's how its broken up:</para>
<screen>-rw-r--r--</screen>
<para>The first character, from left to right, is a special character
that tells if this is a regular file, a directory, a special
character or block device, a socket, or any other special
pseudo-file device. The next three characters, designated as
<literal>rw-</literal> gives the permissions for the owner of the
file. The next three characters, <literal>r--</literal> gives the
permissions for the group that the file belongs to. The final three
characters, <literal>r--</literal>, gives the permissions for the
rest of the world. A dash means that the permission is turned off.
In the case of this file, the permissions are set so the owner can
read and write to the file, the group can read the file, and the
rest of the world can only read the file. According to the table
above, the permissions for this file would be
<literal>644</literal>, where each digit represents the three parts
of the file's permission.</para>
<para>This is all well and good files, but how does the system control
permissions on devices? FreeBSD actually treats most hardware
devices as a file that programs can open, read, and write data to
just like any other file. These special device files are stored on
the <filename>/dev</filename> directory.</para>
<para>Directories are also treated as files. They have read, write,
and execute permissions. The executable bit for a directory has a
slightly different meaning than that of files. When a directory is
marked executable, it means it can be searched into, for example, a
directory listing can be done in that directory.</para>
<para>There are more to permissions, but they are primarily used in
special circumstances such as setuid binaries and sticky
directories. If you want more information on file permissions and
how to set them, be sure to look at the &man.chmod.1; man
page.</para>
</sect1>
<sect1 id="dirstructure">
<title>Directory Structures</title>
<para>Since FreeBSD uses its file systems to determine many
fundamental system operations, the hiarchy of the file system is
extremely important. Due to the fact that the &man.hier.7; man page
provides a complete description of the directory structure, it will
not be duplicated here. Please read &man.hier.7; for more
information.</para>
<para>Of significant importance is the root of all directories, the /
directory. This directory is the first directory mounted at boot
time and it contains the base system necessary at boot time. The
root directory also contains mount points for every other file
system that you want to mount.</para>
<para>A mount point is a directory where additional file systems can
be grafted onto the root file system. Standard mount points include
<filename>/usr</filename>, <filename>/var</filename>,
<filename>/mnt</filename>, and <filename>/cdrom</filename>. These
directories are usually referenced to entries in the file
<filename>/etc/fstab</filename>. <filename>/etc/fstab</filename> is
a table of various file systems and mount points for refence by the
system. Most of the file systems in <filename>/etc/fstab</filename>
are mounted automatically at boot time from the script &man.rc.8;
unless they contain the noauto option. Consult the &man.fstab.5;
manual page for more information on the format of the
<filename>/etc/fstab</filename> file and the options it
contains.</para>
</sect1>
<sect1 id="shells">
<title>Shells</title>
<para>In FreeBSD, a lot of everyday work is done in a command line
interface called a shell. A shell's main job is to take commands
from the input channel and execute them. A lot of shells also have
built in functions to help everyday tasks such a file management,
file globing, command line editing, command mar-cos, and environment
variables. FreeBSD comes with a set of shells, such as sh, the
Bourne Shell, and csh, the C-shell. Many other shells are available
from the FreeBSD Ports Collection that have much more power, such as
tcsh and bash.</para>
<para>Which shell do you use? Its really a matter of taste. If your
a C programmer you might feel more comfortable with a C-like shell
such as tcsh. If you've come from Linux or are new to a UNIX
command line interface you might try bash. The point is that each
shell has unique properties that may or may not work with your
preferred working environment, and that you have a choice of what
shell to use.</para>
<para>One common feature in a shell is file-name completion. Given
the typing of the first few letters of a command or filename, you
can usually have the shell automatically complete the rest of the
command or filename by hitting the TAB key on the keyboard. Here is
an example. I have two files called <filename>foobar</filename> and
<filename>foo.bar</filename>. I want to delete
<filename>foo.bar</filename>. So what I would type on the keyboard
is: <command>rm fo[TAB].[TAB]</command>.</para>
<para>The shell would print out <command>rm
foo[BEEP].bar</command>.</para>
<para>The [BEEP] is the console bell, which is the shell telling me it
was unable to totally complete the filename because there is more
than one match. Both <filename>foobar</filename> and
<filename>foo.bar</filename> start with <literal>fo</literal>, but
it was able to complete to <literal>foo</literal>. Once I typed in
<literal>.</literal>, then hit TAB again, the shell was able to fill
in the rest of the filename for me.</para>
<para>Another function of the shell is environment variables.
Environment variables are a variable key pair stored in the shell's
environment space. This space can be read by any program invoked by
the shell, and thus contains a lot of program configuration. Here
is a list of common environment variables and what they mean:</para>
<informaltable frame="none">
<tgroup cols="2">
<thead>
<row>
<entry>Variable</entry>
<entry>Description</entry>
</row>
</thead>
<tbody>
<row>
<entry><envar>USER</envar></entry>
<entry>Current logged in user's name.</entry>
</row>
<row>
<entry><envar>PATH</envar></entry>
<entry>Colon separated list of directories to search for
binaries.</entry>
</row>
<row>
<entry><envar>DISPLAY</envar></entry>
<entry>Network name of the X11 display to connect to, if
available.</entry>
</row>
<row>
<entry><envar>SHELL</envar></entry>
<entry>The current shell.</entry>
</row>
<row>
<entry><envar>TERM</envar></entry>
<entry>The name of the user's terminal. Used to determine the
capabilites of the terminal.</entry>
</row>
<row>
<entry><envar>TERMCAP</envar></entry>
<entry>Database entry of the terminal escape codes to perform
various terminal functions.</entry>
</row>
<row>
<entry><envar>OSTYPE</envar></entry>
<entry>Type of operating system. E.g., FreeBSD.</entry>
</row>
<row>
<entry><envar>MACHTYPE</envar></entry>
<entry>The CPU architecture that the system is running
on.</entry>
</row>
<row>
<entry><envar>EDITOR</envar></entry>
<entry>The user's preferred text editor.</entry>
</row>
<row>
<entry><envar>PAGER</envar></entry>
<entry>The user's preferred text pager.</entry>
</row>
<row>
<entry><envar>MANPATH</envar></entry>
<entry>Colon separated list of directories to search for
manual pages.</entry>
</row>
</tbody>
</tgroup>
</informaltable>
<para>To view or set an environment variable differs somewhat from
shell to shell. For example, in the C-Style shells such as tcsh
and csh, you would use <command>setenv</command> to set and view
environment variables. Under Bourne shells such as sh and bash, you
would use <command>set</command> and <command>export</command> to
view and set your current environment variables. For example, to
set or modify the <envar>EDITOR</envar> environment variable, under
csh or tcsh a command like this would set <envar>EDITOR</envar> to
<filename>/usr/local/bin/emacs</filename>:</para>
<para><command>setenv EDITOR /usr/local/bin/emacs</command></para>
<para>Under Bourne shells:</para>
<para><command>export EDITOR="/usr/local/bin/emacs"</command></para>
<para>You can also make most shells expand the environment variable by
placing a <literal>$</literal> character in front of it on the
command line. For example, <command>echo $TERM</command> would
print out whatever <envar>$TERM</envar> is set to, because the shell
expands <envar>$TERM</envar> and passes it on to echo.</para>
<para>Shells treat a lot of special characters, called meta-characters
as special representations of data. The most common one is the
<literal>*</literal> character, which represents any number of
characters in a filename. These special meta-characters can be used
to do file name globing. For example, typing in
<command>echo *</command> is almost the same as typing in
<command>ls</command> because the shell takes all the files that
match <command>*</command> and puts them on the command line for
echo to see.</para>
<para>To prevent the shell from interpreting these special characters,
they can be escaped from the shell by putting a backslash
(<literal>\</literal>) character in front of them. <command>echo
$TERM</command> prints whatever your terminal is set to.
<command>echo \$TERM</command> prints <envar>$TERM</envar> as
is.</para>
</sect1>
<sect1 id="editors">
<title>Text Editors</title>
<para>A lot of configuration in FreeBSD is done by editing a text
file. Because of this, it would be a good idea to become familiar
with a text editor. FreeBSD comes with a few as part of the base
system, and many more are available in the ports collection.</para>
<para>The easiest and simplest editor to learn is an editor called
<application>ee</application>, which stands for easy editor. To
start <application>ee</application>, one would type at the command
line <command>ee filename</command> where
<literal>filename</literal> is the name of the file to be edited.
For example, to edit <filename>/etc/rc.conf</filename>, type in
<command>ee /etc/rc.conf</command>. Once inside of ee, all of the
commands for manipulating the editor's functions are listed at the
top of the display. The caret <literal>^</literal> character means
the control key on the keyboard, so ^e expands to pressing the
control key plus the letter <literal>e</literal>. To leave
<application>ee</application>, hit the escape key, then choose leave
editor. The editor will prompt you to save any changes if the file
has been modified.</para>
<para>FreeBSD also comes with more powerful text editors such as
<application>vi</application> as part of the base system, and
<application>emacs</application> and <application>vim</application>
as part of the FreeBSD ports collection. These editors offer much
more functionality and power at the expense of being a little more
complicated to learn. However if you plan on doing a lot of text
editing, learning a more powerful editor such as
<application>vim</application> or <application>emacs</application>
will save you much more time in the long run.</para>
</sect1>
<sect1>
<title>For more information...</title>
<sect2 id="basics-man">
<title>Manual pages</title>
<para>The most comprehensive documentation on FreeBSD is in the form
of man pages. Nearly every program on the system comes with a
short reference manual explaining the basic operation and various
arguments. These manuals can be viewed with the man command. Use
of the man command is simple:</para>
<para><command>&prompt.user; man command</command></para>
<para><literal>command</literal> is the name of the command you
wish to learn about. For example, to learn more about
<command>ls</command> command type:</para>
<para><command>&prompt.user; man ls</command></para>
<para>The online manual is divided up into numbered sections:</para>
<orderedlist>
<listitem>
<para>User commands.</para>
</listitem>
<listitem>
<para>System calls and error numbers.</para>
</listitem>
<listitem>
<para>Functions in the C libraries.</para>
</listitem>
<listitem>
<para>Device drivers.</para>
</listitem>
<listitem>
<para>File formats.</para>
</listitem>
<listitem>
<para>Games and other diversions.</para>
</listitem>
<listitem>
<para>Miscellaneous information.</para>
</listitem>
<listitem>
<para>System maintenance and operation commands.</para>
</listitem>
<listitem>
<para>Kernel developers.</para>
</listitem>
</orderedlist>
<para>In some cases, the same topic may appear in more than one
section of the online manual. For example, there is a chmod user
command and a <literal>chmod()</literal> system call. In this
case, you can tell the man command which one you want by
specifying the section:</para>
<para><command>&prompt.user; man 1 chmod</command></para>
<para>This will display the manual page for the user command
<command>chmod</command>. References to a particular section of
the online manual are traditionally placed in parenthesis in
written documentation, so &man.chmod.1; refers to the
<command>chmod</command> user command and &man.chmod.2; refers to
the system call.</para>
<para>This is fine if you know the name of the command and simply
wish to know how to use it, but what if you cannot recall the
command name? You can use man to search for keywords in the
command descriptions by using the <option>-k</option>
switch:</para>
<para><command>&prompt.user; man -k mail</command></para>
<para>With this command you will be presented with a list of
commands that have the keyword &ldquo;mail&rdquo; in their
descriptions. This is actually functionally equivalent to using
the apropos command.</para>
<para>So, you are looking at all those fancy commands in
<filename>/usr/bin</filename> but do not have the faintest idea
what most of them actually do? Simply do a
<command>&prompt.user; cd /usr/bin; man -f *</command> or
<command>&prompt.user; cd /usr/bin; whatis *</command> which
does the same thing.</para>
</sect2>
<sect2 id="basics-info">
<title>GNU Info Files</title>
<para>FreeBSD includes many applications and utilities produced by
the Free Software Foundation (FSF). In addition to man pages,
these programs come with more extensive hypertext documents called
<literal>info</literal> files which can be viewed with the
<command>info</command> command or, if you installed
<application>emacs</application>, the info mode of
<application>emacs</application>.</para>
<para>To use the &man.info.1; command, simply type:</para>
<para><command>&prompt.user; info</command></para>
<para>For a brief introduction, type <literal>h</literal>. For a
quick command reference, type <literal>?</literal>.</para>
</sect2>
</sect1>
</chapter>
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