index00.sgml

Shall高级编程

         Bash does not recognize</para>
      <para><link linkend="foldref">fold</link>, a filter to wrap lines of
        text</para>
      <para><link linkend="forkref">Forking</link> a <firstterm>child</firstterm>
         process</para>
      <para><link linkend="forloopref1"><firstterm>for</firstterm>
         loops</link></para>

      <para><link linkend="functionref">Functions</link></para>
         <itemizedlist>
      <listitem><para><link linkend="passedargs">Arguments
         passed</link> referred to by position</para></listitem>
      <listitem><para><link linkend="captureretval">Capturing
        the return value</link> of a function
	using <link linkend="echoref">echo</link></para></listitem>
      <listitem><para><link linkend="functdefmust">Definition
         must precede</link> first call to function</para></listitem>
      <listitem><para><link linkend="exitreturn1">Exit
         status</link></para></listitem>
      <listitem>
        <para><link
           linkend="localref1">Local variables</link></para>
        <para>and <link
           linkend="locvarrecur">recursion</link></para></listitem>

      <listitem><para><link linkend="passarray">Passing
        an <firstterm>array</firstterm></link> to a
        function</para></listitem>
      <listitem><para><link
         linkend="funcpointers">Passing pointers</link>
	 to a function</para></listitem>
      <listitem><para><link
         linkend="recursionref0">Recursion</link></para></listitem>
      <listitem><para><link
         linkend="redstdinfunc1">Redirecting
	 <filename>stdin</filename></link>
	 of a function</para></listitem>

      <listitem>
         <para><link linkend="returnref">return</link></para>

         <para><link linkend="retarray">
           Returning an <firstterm>array</firstterm></link> from
	   a function</para>

         <para><link linkend="rvt"><firstterm>return</firstterm>
           range limits</link>, workarounds</para>
      </listitem>

      <listitem><para><link
         linkend="fshiftref"><firstterm>shift</firstterm>
	 arguments passed</link> to a function</para></listitem>
         </itemizedlist>

      <para>* * *</para>

      <para><link linkend="getopty">getopt</link>,
        <firstterm>external</firstterm> command for parsing script
        <firstterm>command-line</firstterm> arguments
	   <itemizedlist>
       <listitem><para><link linkend="getoptsimple1">Emulated
         in a script</link></para></listitem>
	   </itemizedlist></para>

      <para><link linkend="getoptsx">getopts</link>,
        Bash <firstterm>builtin</firstterm> for parsing script
        <firstterm>command-line</firstterm> arguments
	   <itemizedlist>
       <listitem><para><link
         linkend="getoptsopt"><varname>$OPTIND</varname> /
         <varname>$OPTARG</varname></link></para></listitem>
	   </itemizedlist></para>

      <para><link linkend="globbingref2">Globbing</link>,
         filename expansion</para>
      <para><link linkend="ge0ref"> -ge </link>,
         <firstterm>greater-than or equal</firstterm>
	 <link linkend="icomparison1">integer comparison</link> test</para>
      <para><link linkend="gt0ref"> -gt </link>,
         <firstterm>greater-than</firstterm> <link linkend="icomparison1">integer
	 comparison</link> test</para>
      <para><link linkend="groupsref"><varname>$GROUPS</varname></link>,
         <firstterm>Groups</firstterm> user belongs to</para>
      <para><link linkend="gzipref">gzip</link>, compression utility</para>

      <para>* * *</para>

      <para><link linkend="hashref">Hashing</link>, creating lookup keys
         in a table
	   <itemizedlist>
	 <listitem><para><link linkend="hashex2_0"><firstterm>Example
	   script</firstterm></link></para></listitem>
	   </itemizedlist></para>

      <para><link linkend="headref">head</link>, <firstterm>echo</firstterm>
        to <filename>stdout</filename> lines at the beginning of a text
        file</para>
      <para><link linkend="helpref">help</link>, gives usage summary of
        a Bash <link linkend="builtinref">builtin</link></para>

<!-- ********************** -->
      <para><link linkend="heredocref"><firstterm>Here</firstterm>
         documents</link>

	 <itemizedlist>

      <listitem>
        <para><link linkend="anonheredoc0"><firstterm>Anonymous</firstterm>
           here documents</link>, using <command>:</command></para>
        <para><link linkend="cblock1">Commenting out</link>
	   blocks of code</para>
        <para><link linkend="hselfdoc">Self-documenting</link>
	   scripts</para>
      </listitem>
      <listitem><para><link
        linkend="bcheredoc"><firstterm>bc</firstterm> in a <firstterm>here
        document</firstterm></link></para></listitem>

      <listitem><para><link linkend="catscriptref"><firstterm>cat</firstterm>
         scripts</link></para></listitem>
      <listitem><para><link linkend="herecs">Command
         substitution</link></para></listitem>
      <listitem><para><link linkend="exscriptref"><firstterm>ex</firstterm>
         scripts</link></para></listitem>
      <listitem><para><link
         linkend="herefunc"><firstterm>Function</firstterm></link>,
	 supplying input to</para></listitem>

      <listitem>
        <para><link
           linkend="herestringsref"><firstterm>Here</firstterm>
           strings</link></para>
        <para><link linkend="hspre">Prepending text</link></para>
        <para><link linkend="hsread">Using
	   <firstterm>read</firstterm></link></para>
      </listitem>

      <listitem><para><link
      linkend="limitstringref"><firstterm>Limit</firstterm>
      string</link></para>
         <para><link linkend="indentedls">Closing <firstterm>limit
            string</firstterm></link> may not be indented</para>
         <para><link linkend="limitstrdash">Dash option</link>
           to limit string, <option>&lt;&lt;-LimitString</option>
           </para></listitem>
      <listitem><para><link linkend="herelit">Literal
         text output</link>,
	 for generating program code</para></listitem>

      <listitem>
         <para><link linkend="hereparamsub">Parameter
           substitution</link></para>
	 <para><link linkend="hereesc">Disabling</link>
	   <firstterm>parameter substitution</firstterm></para>
      </listitem>

      <listitem><para><link linkend="herepassp">Passing
         parameters</link></para></listitem>
      <listitem><para><link linkend="heretemp">Temporary
         files</link></para></listitem>
      <listitem><para><link linkend="vihere">Using
        <firstterm>vi</firstterm> non-interactively</link></para></listitem>
	 </itemizedlist></para>
<!-- ********************** -->

      <para><link linkend="histcommands">History commands</link></para>

      <para><link linkend="homedirref"><varname>$HOME</varname></link>,
         <firstterm>user's home directory</firstterm></para>
      <para><link linkend="homework">Homework assignment solver</link></para>
      <para><link linkend="hostnameref"><varname>$HOSTNAME</varname></link>,
        system <firstterm>host name</firstterm></para>

      <para>* * *</para>

<!-- ********************** -->
      <para><link linkend="ifthen">if [ condition ]; then ...</link>
         <firstterm>test</firstterm> construct
	 <itemizedlist>

      <listitem>
        <para><link linkend="ifgrepref">if-grep</link>,
          <firstterm>if</firstterm> and <link linkend="grepref">grep</link>
          in combination</para>
        <para><link linkend="ifgrepfix">Fixup</link>
          for <firstterm>if-grep</firstterm> test</para>
      </listitem>

         </itemizedlist></para>
<!-- ********************** -->

      <para><link linkend="ifsref"><varname>$IFS</varname></link>,
         <firstterm>Internal field separator</firstterm> variable
	   <itemizedlist>
      <listitem><para><link linkend="ifsws">Defaults to
        <firstterm>whitespace</firstterm></link></para></listitem>
	   </itemizedlist></para>

      <para><link linkend="icomparison1">Integer comparison
         operators</link></para>
      <para><link linkend="doinref">in</link>,
         <firstterm>keyword</firstterm> preceding
         <varname>[list]</varname> in a <firstterm>for</firstterm>
         loop</para>
      <para><link linkend="inittabref">Initialization table</link>,
         <filename>/etc/inittab</filename></para>
      <para><link linkend="iitest">Interactive script</link>, test for</para>
      <para><link linkend="ioredirref">I/O redirection</link></para>

<!-- ********************** -->
      <para><link linkend="ivrref">Indirect referencing of variables</link>
         <itemizedlist>
      <listitem><para><link linkend="ivr2">New notation</link>, introduced
         in version 2 of Bash</para></listitem>
      <listitem><para><link linkend="varrefnew">
         Example script</link></para></listitem>
         </itemizedlist></para>
<!-- ********************** -->

      <para><link linkend="iterationref">Iteration</link></para>

      <para>* * *</para>

      <para><link linkend="jobidtable0">Job IDs</link>, table</para>

      <para><link linkend="jotref">jot</link>,
        Emit a sequence of integers. Equivalent to <link
        linkend="seqref">seq</link>.
	  <itemizedlist>
       <listitem><para><link linkend="jotrandom">Random sequence
         generation</link></para></listitem>
         </itemizedlist></para>

      <para>* * *</para>

      <para><link linkend="keywordref">Keywords</link></para>

      <para><link linkend="killref">kill</link>,
        terminate a process by <link linkend="processiddef">process ID</link>
	  <itemizedlist>
      <listitem><para><link
        linkend="zombieref">Options</link> (<option>-l</option>,
	<option>-9</option>)</para></listitem>
         </itemizedlist></para>

      <para><link linkend="killallref">killall</link>,
        terminate a process <emphasis>by name</emphasis></para>
      <para><link linkend="killall2ref"><firstterm>killall
         script</firstterm></link> in <filename
         class="directory">/etc/rc.d/init.d</filename></para>

      <para>* * *</para>

      <para><link linkend="le0ref"> -le </link>,
         <firstterm>less-than or equal</firstterm>
	 <link linkend="icomparison1">integer comparison</link> test</para>
      <para><link linkend="letref">let</link>,
        setting and carrying out arithmetic operations on variables</para>
      <para><link linkend="limitstringref">Limit string</link>,
         in a <link linkend="heredocref">here document</link></para>
      <para><link linkend="linenoref"><varname>$LINENO</varname></link>,
         variable indicating the <firstterm>line number</firstterm> where
         it appears in a script</para>

      <para><link linkend="linkref">Link</link>, file
         (using <firstterm>ln</firstterm> command)
	     <itemizedlist>
        <listitem><para><link
	  linkend="linkminvok">Invoking script with multiple names</link>,
          using <firstterm>ln</firstterm></para></listitem>
        <listitem><para><link
	  linkend="symlinkref"><firstterm>symbolic</firstterm>
	  links</link>, <firstterm>ln -s </firstterm></para></listitem>
             </itemizedlist></para>

      <para><link linkend="listconsref">List constructs</link>
        <itemizedlist>

      <listitem><para><link linkend="lcons1"><firstterm>And</firstterm>
        list</link></para></listitem>
      <listitem><para><link linkend="orlistref"><firstterm>Or</firstterm>
        list</link></para></listitem>
        </itemizedlist></para>

      <para><link linkend="localref1">Local variables</link>
         <itemizedlist>
      <listitem><para>and <link
        linkend="locvarrecur">recursion</link></para></listitem>
         </itemizedlist></para>

      <para><link linkend="localization">Localization</link></para>

      <para><link linkend="logops1">Logical operators</link>
         (<varname>&amp;&amp;</varname>, <varname>||</varname>,
         etc.)</para>
      <para><link linkend="logoutfileref1">Logout file</link>,
         the <filename>~/.bash_logout</filename> file</para>


      <para><link linkend="loops1">Loops</link>
        <itemizedlist>

      <listitem><para><link linkend="brkcont1">break</link>
         loop control command</para></listitem>
      <listitem><para><link linkend="brkcont1">continue</link> loop
        control command</para></listitem>

      <listitem>
        <para><firstterm>C</firstterm>-style
	loop within <link linkend="dblparensref">double
	parentheses</link></para>
	<para><link
	  linkend="loopcstyle"><firstterm>for</firstterm> loop</link></para>
	<para><link
	  linkend="wloopcstyle"><firstterm>while</firstterm> loop</link></para>
	</listitem>

      <listitem><para><link linkend="doinref">do</link> (keyword),
         begins execution of commands within a loop</para></listitem>
      <listitem><para><link linkend="doinref">done</link> (keyword),
         terminates a loop</para></listitem>

      <listitem>
        <para><link linkend="forloopref1"><firstterm>for</firstterm>
           loops</link></para>
        <para><replaceable>for</replaceable> <varname>arg</varname>
          <replaceable>in</replaceable> <varname>[list]</varname>;
          <replaceable>do</replaceable></para>

        <para><link linkend="loopcs"><firstterm>Command
	  substitution</firstterm> to generate
	  <varname>[list]</varname></link></para>
        <para><link linkend="liglob">Filename expansion
	  in <varname>[list]</varname></link></para>
        <para><link linkend="multparaml">Multiple parameters
	  i