index00.sgml

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         quoting</link></para>

      <para><command>" ... " </command>
         (double quotes)
         <link linkend="dblquo"><firstterm>weak</firstterm>
         quoting</link></para>


<!-- ********************** -->
      <para><command>() </command> Parentheses
         <itemizedlist>

      <listitem><para><command>( ... ) </command>
         <link linkend="parensref">Command group</link>;
	 starts a
	 <link linkend="subshellsref">subshell</link></para></listitem>
      <listitem><para><command>( ... ) </command>
         <link linkend="parengrps">Enclose group</link>
	 of <firstterm>Extended Regular
	 Expressions</firstterm></para></listitem>
    <listitem>
      <para><command>&gt;( ... )</command></para>
      <para><command>&lt;( ... ) </command>
      <link linkend="processsubref">Process substitution</link></para>
   </listitem>

      <listitem><para><command> ... ) </command>
         <link linkend="caseparen">Terminates test-condition</link>
	 in <firstterm>case</firstterm> construct</para></listitem>
      <listitem><para><command>(( ... )) </command>
         <link linkend="dblparensref">Double parentheses</link>,
         in arithmetic expansion</para></listitem>
         </itemizedlist></para>
<!-- ********************** -->

      <para><command>[ </command> <link linkend="leftbracket">Left bracket</link>,
        <firstterm>test</firstterm> construct</para>

      <para><command>[ ]</command>Brackets
         <itemizedlist>
      <listitem><para><link linkend="brackarray"><firstterm>Array</firstterm>
        element</link></para></listitem>
      <listitem><para><link linkend="bracketsref">Enclose character set
        to match</link> in a <firstterm>Regular
	Expression</firstterm></para></listitem>
      <listitem><para><link
        linkend="bracktest"><firstterm>Test</firstterm> construct</link></para>
      </listitem>
         </itemizedlist></para>


      <para><command>[[ ... ]]</command>
         <link linkend="dblbrackets">Double brackets</link>,
	 extended <firstterm>test</firstterm> construct</para>

      <para><command>$ </command>
        <link linkend="dollarsignref"><firstterm>Anchor</firstterm></link>,
          in a <link linkend="regexref">Regular Expression</link></para>
      <para><command>$ </command>
         <link linkend="varsubn">Prefix to a variable name</link></para>
      <para><command>$( ... ) </command>
         <link linkend="commandsubref0">Command substitution</link>,
	 setting a variable with output of a command,
	 using parentheses notation</para>
      <para><command>` ... ` </command>
         <link linkend="backquotesref">Command substitution</link>,
	 using <link linkend="backticksref">backquotes</link>
	 notation</para>

<!-- ********************** -->
      <para><command>${ ... }</command> Variable manipulation / evaluation

         <itemizedlist>
      <listitem><para><command>${var}</command>
      <link linkend="pssub1">Value of a variable</link></para></listitem>

      <listitem><para><command>${#var}</command>
      <link linkend="psorex1">Length of a variable</link></para></listitem>

      <listitem>
      <para><command>${#@}</command></para>
      <para><command>${#*}</command>
        <link linkend="numposparam">Number of
	 <firstterm>positional
	 parameters</firstterm></link></para></listitem>

      <listitem>
      <para><command>${parameter?err_msg}</command>
         <link linkend="qerrmsg">Parameter-unset
        message</link></para></listitem>

      <listitem>
      <para><command>${parameter-default}</command></para>
      <para><command>${parameter:-default}</command></para>
      <para><command>${parameter=default}</command></para>
      <para><command>${parameter:=default}</command>
      <link linkend="defparam1">Set default
      parameter</link></para></listitem>

      <listitem>
        <para><command>${parameter+alt_value}</command></para>
	<para><command>${parameter:+alt_value}</command></para>
        <para><link linkend="paramaltv">Alternate value</link>
          of parameter, if set</para>
      </listitem>

      <listitem>
	 <para><command>${!var}</command></para>
         <para><link linkend="ivr2">Indirect referencing of a variable</link>,
	   new notation</para>
      </listitem>

      <listitem>
        <para><command>${!varprefix*}</command></para>
        <para><command>${!varprefix@}</command></para>
      <para><link linkend="varprefixm">Match
        <emphasis>names</emphasis></link> of all previously declared
        variables beginning with <varname>varprefix</varname></para>
      </listitem>

      <listitem>
      <para><command>${string:position}</command></para>
      <para><command>${string:position:length}</command>
      <link linkend="substrextr01">Substring
      extraction</link></para></listitem>

      <listitem>
      <para><command>${var#Pattern}</command></para>
      <para><command>${var##Pattern}</command>
      <link linkend="psorex2">Substring
      removal</link></para></listitem>

      <listitem>
      <para><command>${var%Pattern}</command></para>
      <para><command>${var%%Pattern}</command>
      <link linkend="pctpatref">Substring
        removal</link></para></listitem>

      <listitem>
      <para><command>${string/substring/replacement}</command></para>
      <para><command>${string//substring/replacement}</command></para>
      <para><command>${string/#substring/replacement}</command></para>
      <para><command>${string/%substring/replacement}</command>
      <link linkend="substrrepl00">Substring
      replacement</link></para></listitem>

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

      <para><command>\ </command>
         <link linkend="escp">Escape</link> the character following
	    <itemizedlist>
      <listitem><para><command>\&lt; ... \&gt; </command>
         <link linkend="anglebrac">Angle brackets</link>,
         <firstterm>escaped</firstterm>,
	 word boundary in a <link linkend="regexref">Regular
	 Expression</link></para></listitem>
      <listitem><para><command>\{ N \}</command>
         <link linkend="escpcb"><quote>Curly</quote> brackets</link>,
         <firstterm>escaped</firstterm>,
	 number of character sets to match in an <link
	 linkend="extregex">Extended RE</link></para></listitem>
      <listitem><para><command>\; </command>
         <link linkend="findref0"><firstterm>Semicolon</firstterm></link>,
         <firstterm>escaped</firstterm>,
	 terminates a <link linkend="findref">find</link>
	 command</para></listitem>
      <listitem><para><command>\$$ </command> <link linkend="ivrref">Indirect
        reverencing of a variable</link>, old-style notation</para></listitem>
      <listitem><para><link linkend="escnewline">Escaping
        a <firstterm>newline</firstterm></link>,
	to write a multi-line command</para></listitem>
	    </itemizedlist></para>

<!-- ********************** -->
      <para><command>&amp; </command>
         <itemizedlist>

	 <listitem><para>
            <command>&amp;&gt; </command>
         <link linkend="redirouterror">Redirect
	    <emphasis>both</emphasis> <filename>stdout</filename>
	    and <filename>stderr</filename></link> of a command to a
	    file</para></listitem>

	 <listitem><para>
            <command>&gt;&amp;j </command>
            <link linkend="ioredirectionref1">Redirect
	    <filename>stdout</filename></link> to
	    <firstterm>file descriptor</firstterm>
	    <firstterm>j</firstterm></para>
	 <para>
            <command>&gt;&amp;2 </command>
         <link linkend="redirouterror2">Redirect
	    <filename>stdout</filename></link> of a command to
	    <filename>stderr</filename></para></listitem>

	 <listitem><para>
            <command>i&gt;&amp;j </command>
            <link linkend="ioredirectionref1">Redirect
	    <firstterm>file descriptor</firstterm></link>
	    <firstterm>i</firstterm> to
	    <firstterm>file descriptor</firstterm>
	    <firstterm>j</firstterm></para>
	 <para>
            <command>2&gt;&amp;1 </command>
         <link linkend="ioredirectionref1">Redirect
	    <filename>stderr</filename></link> to
	    <filename>stdout</filename></para></listitem>

      <listitem><para><link linkend="cfd">Closing <firstterm>file
      descriptors</firstterm></link></para>

        <para><command>n&lt;&amp;-</command>
           Close input file descriptor
	   <firstterm>n</firstterm></para>
        <para><command>0&lt;&amp;-</command>,
	   <command>&lt;&amp;-</command>
           Close <filename>stdin</filename></para>
        <para><command>n&gt;&amp;-</command>
          Close output file descriptor
	  <firstterm>n</firstterm></para>
        <para><command>1&gt;&amp;-</command>,
	   <command>&gt;&amp;-</command>
	   Close <filename>stdout</filename></para></listitem>


         <listitem><para>
	    <command>&amp;&amp; </command>
	    <link linkend="logicaland">Logical AND
	    test operator</link></para></listitem>

         <listitem><para>
	    <command>Command &</command>
	    <link linkend="bgjob">Run job in
            <firstterm>background</firstterm></link></para></listitem>

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



      <para><command># </command>
         <link linkend="hashmarkref">Hashmark</link>,
         special symbol beginning a script
         <firstterm>comment</firstterm></para>

      <para><command>#!</command>
         <link linkend="shabangref">Sha-bang</link>,
         special string starting a
         <link linkend="whatsascript">shell script</link></para>

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

	 <listitem><para>
         <link linkend="asteriskref"><firstterm>Wild
         card</firstterm></link>,
	 in <link linkend="globbingref">globbing</link>
	 </para></listitem>

	 <listitem><para>
         <link linkend="asteriskref2">Any number of characters</link>
	 in a <link linkend="regexref">Regular Expression</link>
	 </para></listitem>
	    
	 <listitem><para>
            <command> ** </command>
         <link linkend="exponentiationref">Exponentiation</link>,
	 arithmetic operator
	 </para></listitem>

         </itemizedlist>
	 </para>
<!-- ********************** -->
      <para><command>% </command> Percent sign
         <itemizedlist>

	 <listitem><para>
         <link linkend="moduloref">Modulo</link>, division-remainder
         arithmetic operation
	 </para></listitem>

	 <listitem><para>
         <link linkend="pctpatref">Substring removal</link>
	   (pattern matching) operator</para></listitem>

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

      <para><command>+ </command> Plus sign
         <itemizedlist>
         <listitem><para><link linkend="plusref"><firstterm>Character
           match</firstterm></link>, in an <link
           linkend="extregex">extended Regular
           Expression</link></para></listitem>
        <listitem><para><link linkend="paramaltv">Prefix to
	   <firstterm>alternate parameter</firstterm></link>, in
	   <firstterm>parameter substitution</firstterm></para></listitem>
        <listitem><para><command> ++ </command>
           <link linkend="plusplusref"><firstterm>C-style</firstterm>
           variable increment</link>, within <firstterm>double
           parentheses</firstterm></para></listitem>
         </itemizedlist></para>

      <para>* * *</para>

      <para><firstterm>Shell Variables</firstterm></para>

      <para><command>$_ </command>
        <link linkend="underscoreref">Last argument to previous
	command</link></para>
      <para><command>$- </command>
        <link linkend="flpref">Flags passed to script</link>, using <link
          linkend="setref">set</link></para>
      <para><command>$! </command>
         <link linkend="pidvarref"><firstterm>Process ID</firstterm>
         of last background job</link></para>
      <para><command>$? </command>
         <link linkend="exsref"><firstterm>Exit
         status</firstterm> of a command</link></para>
      <para><command>$@ </command>
         All the <firstterm>positional parameters</firstterm>, <link
         linkend="appref2">as <emphasis>separate</emphasis>
         words</link></para>
      <para><command> $* </command>
         All the <firstterm>positional parameters</firstterm>, <link
         linkend="appref">as a <emphasis>single</emphasis>
         word</link></para>
      <para><command>$$ </command>
         <link linkend="processidref">Process ID</link> of the
         script</para>
      <para><command>$# </command>
         <link linkend="clacountref">Number of arguments passed</link> to a