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Rewrap minimal-sh

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PR:		174029
Submitted by:	Derek Wood <ddwood@highdensity.org>
Approved by:	bcr (mentor)
This commit is contained in:
Eitan Adler 2012-12-07 13:00:58 +00:00
parent fea381ec1f
commit bab98b75e1
Notes: svn2git 2020-12-08 03:00:23 +00:00 
svn path=/head/; revision=40297
1 changed files with 18 additions and 17 deletions
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35
en_US.ISO8859-1/books/faq/book.xml
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@ -3980,33 +3980,34 @@ kern.timecounter.hardware: TSC -&gt; i8254</screen>
<qandaentry>
<question id="minimal-sh">
<para>Why is <command>/bin/sh</command> so minimal? Why does
&os; not use <command>bash</command> or another
<para>Why is <command>/bin/sh</command> so minimal? Why
does &os; not use <command>bash</command> or another
shell?</para>
</question>
<answer>
<para>Many people need to write
shell scripts which will be portable across many systems.
That is why &posix; specifies the shell and utility commands
in great detail. Most scripts are written in Bourne shell (&man.sh.1;),
and because several important programming interfaces
(&man.make.1;, &man.system.3;, &man.popen.3;, and analogues
in higher-level scripting languages like Perl and Tcl) are
specified to use the Bourne shell to interpret commands.
Because the Bourne shell is so often and widely used, it is
important for it to be quick to start, be deterministic in
its behavior, and have a small memory footprint.</para>
<para>Many people need to write shell scripts which will be
portable across many systems. That is why &posix;
specifies the shell and utility commands in great detail.
Most scripts are written in Bourne shell (&man.sh.1;), and
because several important programming interfaces
(&man.make.1;, &man.system.3;, &man.popen.3;, and
analogues in higher-level scripting languages like Perl
and Tcl) are specified to use the Bourne shell to
interpret commands. Because the Bourne shell is so often
and widely used, it is important for it to be quick to
start, be deterministic in its behavior, and have a small
memory footprint.</para>
<para>The existing implementation is our best effort at
meeting as many of these requirements simultaneously as we
can. In order to keep <command>/bin/sh</command> small, we
have not provided many of the convenience features that
can. In order to keep <command>/bin/sh</command> small,
we have not provided many of the convenience features that
other shells have. That is why the Ports Collection
includes more featureful shells like
<command>bash</command>, <command>scsh</command>,
&man.tcsh.1;, and <command>zsh</command>. (You
can compare for yourself the memory utilization of all these
&man.tcsh.1;, and <command>zsh</command>. (You can
compare for yourself the memory utilization of all these
shells by looking at the <quote>VSZ</quote> and
<quote>RSS</quote> columns in a <command>ps
<option>-u</option></command> listing.)</para>