ch05_03.htm

unix基础教程

can be expanded to its full name when the Escape key is pressed.  
If more than one filename matches, type <em class="emphasis">EOF</em> 
to list possible completions.</p>
</td></tr>
<tr><td><tt class="literal">hardpaths</tt></td><td><p>Tell <tt class="literal">dirs</tt> to display the actual pathname
<a name="IXT-5-122938" />
of any directory that is a symbolic link.</p>
</td></tr>
<tr><td><tt class="literal">histchars=</tt><em class="replaceable"><tt>ab</tt></em></td><td><p>A two-character string that sets the characters to use
<a name="IXT-5-122939" />
in history-substitution and quick-substitution (default is <tt class="literal">!^</tt>).</p>
</td></tr>
<tr><td><tt class="literal">history=</tt><em class="replaceable"><tt>n</tt></em></td><td><p>
<a name="IXT-5-122940" />Number of commands to save in history list.</p>
</td></tr>
<tr><td><tt class="literal">home=</tt><em class="replaceable"><tt>dir</tt></em></td><td><p>Home directory of user, initialized from HOME. 
<a name="IXT-5-122941" />
The <tt class="literal">~</tt> character is shorthand for this value.</p>
</td></tr>
<tr><td><tt class="literal">ignoreeof</tt></td><td><p>
<a name="IXT-5-122942" />Ignore an end-of-file (<em class="emphasis">EOF</em>) from terminals;
prevents accidental logout.</p>
</td></tr>
<tr><td><tt class="literal">mail=(</tt><em class="replaceable"><tt>n file</tt></em><tt class="literal">)</tt></td><td><p>
<a name="IXT-5-122943" />One or more files checked for new mail every five minutes or
(if <em class="emphasis">n</em> is supplied) every <em class="emphasis">n</em> seconds.</p>
</td></tr>
<tr><td><tt class="literal">nobeep</tt></td><td><p>
<a name="IXT-5-122944" />Don't ring bell for ambiguous file completion (see <tt class="literal">filec</tt>).</p>
</td></tr>
<tr><td><tt class="literal">noclobber</tt></td><td><p>Don't redirect output to an existing file; prevents accidental
<a name="IXT-5-122945" />
destruction of files.</p>
</td></tr>
<tr><td><tt class="literal">noglob</tt></td><td><p>
<a name="IXT-5-122946" />Turn off filename expansion; useful in shell scripts.</p>
</td></tr>
<tr><td><tt class="literal">nonomatch</tt></td><td><p>
<a name="IXT-5-122947" />Treat filename metacharacters as literal characters;
e.g., <tt class="literal">vi ch*</tt> creates new file 
<tt class="literal">ch*</tt> instead of printing &#8220;No match.&#8221;</p>
</td></tr>
<tr><td><tt class="literal">notify</tt></td><td><p>Notify user of completed jobs right away,
<a name="IXT-5-122948" />
instead of waiting for the next prompt.</p>
</td></tr>
<tr><td><tt class="literal">path=(</tt><em class="replaceable"><tt>dirs</tt></em><tt class="literal">)</tt></td><td><p>	List of pathnames in which to search for commands to execute.
	Initialized from PATH.
	SVR4 default is <tt class="literal">( . /usr/ucb /usr/bin )</tt>.
	On Solaris, the default path is
	<tt class="literal">( /usr/bin . )</tt>.
	However, the standard start-up scripts then change it to
	<tt class="literal">( /bin /usr/bin /usr/ucb /etc . )</tt>.
	</p>
</td></tr>
<tr><td><tt class="literal">prompt='</tt><em class="replaceable"><tt>str</tt></em><tt class="literal">'</tt></td><td><p>
<a name="IXT-5-122949" />String that prompts for interactive input;
default is <tt class="literal">%</tt>.  </p>
</td></tr>
<tr><td><tt class="literal">savehist=</tt><em class="replaceable"><tt>n</tt></em></td><td><p>Number of history commands to save in
<a name="IXT-5-122950" />
<tt class="literal">~/.history</tt> upon logout; they can be accessed
at the next login.</p>
</td></tr>
<tr><td><tt class="literal">shell=</tt><em class="replaceable"><tt>file</tt></em></td><td><p>Pathname of the shell program currently in use;
default is <tt class="literal">/bin/csh</tt>.
<a name="IXT-5-122951" /></p>
</td></tr>
<tr><td><tt class="literal">status=</tt><em class="replaceable"><tt>n</tt></em></td><td><p>Exit status of last command.  Built-in commands return
<a name="IXT-5-122952" />
0 (success) or 1 (failure).</p>
</td></tr>
<tr><td><tt class="literal">term=</tt><em class="replaceable"><tt>ID</tt></em></td><td><p>Name of terminal type,
same as TERM.
<a name="IXT-5-122953" /></p>
</td></tr>
<tr><td><tt class="literal">time='</tt><em class="replaceable"><tt>n</em> <tt class="literal">%</tt><em class="replaceable">c</em><tt class="literal">'</tt></td><td><p>If command execution takes more than <em class="emphasis">n</tt></em> CPU seconds,
<a name="IXT-5-122954" />
report user time, system time, elapsed time, and CPU percentage.
Supply optional <tt class="literal">%</tt><em class="emphasis">c</em> flags to show other data.</p>
</td></tr>
<tr><td><tt class="literal">user=</tt><em class="replaceable"><tt>name</tt></em></td><td><p>Login name of user, initialized from USER.
<a name="IXT-5-122955" /></p>
</td></tr>
<tr><td><tt class="literal">verbose</tt></td><td><p>Display a command after history substitution; same as the 
<a name="IXT-5-122956" />
command <tt class="literal">csh -v</tt>.</p>
</td></tr>
</table><p>
</div>

<a name="unut-ch-5-sect-3.4" /><div class="sect2"><h3 class="sect2">5.3.4. Example .cshrc File</h3><p>
<a name="IXT-5-122957" /></p>
<blockquote><pre class="code"># PREDEFINED VARIABLES
set path=(~ ~/bin /usr/ucb /bin /usr/bin . )
set mail=(/var/mail/tom)

if ($?prompt) then            # Settings for interactive use
  set echo
  set filec
  set noclobber ignoreeof

  set cdpath=(/usr/lib /var/spool/uucp)
# Now I can type cd macros 
# instead of cd /usr/lib/macros

  set fignore=.o              # Ignore object files for filec
  set history=100 savehist=25
  set prompt='tom \!% '       # Includes history number
  set time=3

# MY VARIABLES

  set man1="/usr/man/man1"    # Lets me do    cd $man1, ls $man1
  set a="[a-z]*"              # Lets me       do vi $a
  set A="[A-Z]*"              # Or            grep string $A

# ALIASES

  alias c "clear; dirs"       # Use quotes to protect ; or |
  alias h "history | more"
  alias j jobs -l
  alias ls ls -sFC            # Redefine ls command
  alias del 'mv \!* ~/tmp_dir'# A safe alternative to rm
endif</pre></blockquote>
</div>

<a name="unut-ch-5-sect-3.5" /><div class="sect2"><h3 class="sect2">5.3.5. Environment Variables</h3><p>
<a name="IXT-5-122958" />
<a name="IXT-5-122959" />The C shell maintains a set of <em class="emphasis">environment variables</em>,
which are distinct from shell variables and aren't really part of 
the C shell.
Shell variables are meaningful only within the current shell, but
environment variables are automatically exported,
making them available globally.
For example, C shell variables are accessible 
only to a particular script in which they're defined, whereas
environment variables can be used
by any shell scripts, mail utilities, or editors you might invoke.</p>
<p>Environment variables are assigned as follows:</p>
<blockquote><pre class="code">setenv <em class="replaceable"><tt>VAR value</tt></em></pre></blockquote>


<p>By convention, environment variable names are all uppercase.
You can create your own environment variables,


or you can use the following predefined environment variables.</p>
<p>These environment variables have a corresponding C shell variable:</p>
<dl><dt><i>HOME</i></dt><dd>
<a name="IXT-5-122960" />Home directory; same as <tt class="literal">home</tt>.
These may be changed independently of each other.</p>
</dd>
<dt><i>PATH</i></dt><dd>
<a name="IXT-5-122961" />Search path for commands; same as <tt class="literal">path</tt>.
Changing either one updates the value stored in the other.</p>
</dd>
<dt><i>TERM</i></dt><dd>
<a name="IXT-5-122962" />Terminal type; same as <tt class="literal">term</tt>.
Changing <tt class="literal">term</tt> updates TERM, but not
the other way around.</p>
</dd>
<dt><i>USER</i></dt><dd>
<a name="IXT-5-122963" />Username; same as <tt class="literal">user</tt>.
Changing <tt class="literal">user</tt> updates USER, but not
the other way around.</p>
</dd>
</dl>
<p>Other environment variables include the following:</p>
<dl><dt><i>EXINIT</i></dt><dd>A string of <tt class="literal">ex</tt> commands similar to those found in
<a name="IXT-5-122964" />
the startup <tt class="literal">.exrc</tt> file (e.g., <tt class="literal">set ai</tt>).
Used by <tt class="literal">vi</tt> and <tt class="literal">ex</tt>.</p>
</dd>
<dt><i>LOGNAME</i></dt><dd>
<a name="IXT-5-122965" />Another name for the USER variable.</p>
</dd>
<dt><i>MAIL</i></dt><dd>The file that holds mail.  Used by mail programs.
<a name="IXT-5-122966" />
This is not the same as the C shell <tt class="literal">mail</tt> variable,
which only checks for new mail.</p>
</dd>
<dt><i>PWD</i></dt><dd>
<a name="IXT-5-122967" />The current directory; the value is copied from <tt class="literal">cwd</tt>.</p>
</dd>
<dt><i>SHELL</i></dt><dd>Undefined by default; once initialized to <tt class="literal">shell</tt>,
<a name="IXT-5-122968" />
the two are identical.</p>
</dd>
</dl>

<a name="IXT-5-122969" />
<a name="IXT-5-122970" /></div>


<hr width="684" align="left" />
<div class="navbar"><table width="684" border="0"><tr><td align="left" valign="top" width="228"><a href="ch05_02.htm"><img src="../gifs/txtpreva.gif" alt="Previous" border="0" /></a></td><td align="center" valign="top" width="228"><a href="index.htm"><img src="../gifs/txthome.gif" alt="Home" border="0" /></a></td><td align="right" valign="top" width="228"><a href="ch05_04.htm"><img src="../gifs/txtnexta.gif" alt="Next" border="0" /></a></td></tr><tr><td align="left" valign="top" width="228">5.2. Syntax</td><td align="center" valign="top" width="228"><a href="index/index.htm"><img src="../gifs/index.gif" alt="Book Index" border="0" /></a></td><td align="right" valign="top" width="228">5.4. Expressions</td></tr></table></div>
<hr width="684" align="left" />

<img src="../gifs/navbar.gif" usemap="#library-map" border="0" alt="Library Navigation Links" />
<p><p><font size="-1"><a href="copyrght.htm">Copyright &copy; 2003</a> O'Reilly &amp; Associates. All rights reserved.</font></p>

<map name="library-map">
<area shape="rect" coords="1,0,88,96" href="../index.htm"><area shape="rect" coords="90,0,165,96" href="../upt/index.htm"><area shape="rect" coords="168,1,253,107" href="../mac/index.htm"><area shape="rect" coords="255,0,335,97" href="../korn/index.htm"><area shape="rect" coords="337,0,415,109" href="../unixnut/index.htm"><area shape="rect" coords="417,0,512,122" href="../sedawk/index.htm"><area shape="rect" coords="514,0,605,105" href="../lunix/index.htm"><area shape="rect" coords="611,2,694,121" href="../vi/index.htm">
</map>

</body></html>