ch08_19.htm

the unix power tools

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><TD
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>${<CODE
CLASS="replaceable"
><I
>var</I
></CODE
>%%<CODE
CLASS="replaceable"
><I
>pat</I
></CODE
>}</TD
><TD
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>ksh, bash</TD
><TD
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><P
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>Value of <CODE
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><I
>var</I
></CODE
> with largest <CODE
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><I
>pat</I
></CODE
> deleted from end.</P
></TD
><TD
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><A
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HREF="ch09_07.htm"
TITLE="String Editing in ksh and bash "
>9.7</A
></TD
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><TR
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><TD
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>|</TD
><TD
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>csh, sh</TD
><TD
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>Pipe standard output.</TD
><TD
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><P
CLASS="para"
><A
CLASS="xref"
HREF="ch01_04.htm"
TITLE="Using Pipes to Create a New Tool "
>1.4</A
>,
<A
CLASS="xref"
HREF="ch13_01.htm#UPT-ART-1023"
TITLE="Using Standard Input and Output"
>13.1</A
></P
></TD
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><TR
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><TD
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>|&amp;</TD
><TD
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>csh</TD
><TD
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>Pipe standard output and standard error.</TD
><TD
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><A
CLASS="xref"
HREF="ch13_05.htm"
TITLE="Redirection in C Shell: Capture Errors, Too? "
>13.5</A
></TD
></TR
><TR
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><TD
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>^</TD
><TD
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>sh <EM
CLASS="emphasis"
>only</EM
></TD
><TD
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>Pipe character (obsolete).</TD
><TD
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></TD
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><TR
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><TD
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>^</TD
><TD
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>csh, bash</TD
><TD
CLASS="entry"
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>Edit previous command line.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch11_05.htm"
TITLE="My Favorite Is ^^ "
>11.5</A
></TD
></TR
><TR
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><TD
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>&amp;</TD
><TD
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>csh, sh</TD
><TD
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>Run program in background.</TD
><TD
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><P
CLASS="para"
><A
CLASS="xref"
HREF="ch01_27.htm"
TITLE="How Background Processing Works "
>1.27</A
>,
<A
CLASS="xref"
HREF="ch01_28.htm"
TITLE="Some Gotchas with Background Processing "
>1.28</A
></P
></TD
></TR
><TR
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><TD
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>?</TD
><TD
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>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
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>Match one character.</TD
><TD
CLASS="entry"
ROWSPAN="1"
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><P
CLASS="para"
><A
CLASS="xref"
HREF="ch01_16.htm"
TITLE="Wildcards "
>1.16</A
>,
<A
CLASS="xref"
HREF="ch15_02.htm"
TITLE="Filename Wildcards in a Nutshell "
>15.2</A
></P
></TD
></TR
><TR
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><TD
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>*</TD
><TD
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>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
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>Match zero or more characters.</TD
><TD
CLASS="entry"
ROWSPAN="1"
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><P
CLASS="para"
><A
CLASS="xref"
HREF="ch01_16.htm"
TITLE="Wildcards "
>1.16</A
>,
<A
CLASS="xref"
HREF="ch15_02.htm"
TITLE="Filename Wildcards in a Nutshell "
>15.2</A
></P
></TD
></TR
><TR
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><TD
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>;</TD
><TD
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>csh, sh</TD
><TD
CLASS="entry"
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>Command separator.</TD
><TD
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ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch08_05.htm"
TITLE="Command-Line Evaluation "
>8.5</A
></TD
></TR
><TR
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><TD
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>;;</TD
><TD
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ROWSPAN="1"
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>sh</TD
><TD
CLASS="entry"
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>End of <EM
CLASS="emphasis"
>case</EM
> statement.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_05.htm"
TITLE="Test String Values with Bourne Shell case "
>44.5</A
></TD
></TR
><TR
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><TD
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>~</TD
><TD
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>csh, ksh, bash</TD
><TD
CLASS="entry"
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>Home directory.</TD
><TD
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ROWSPAN="1"
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><A
CLASS="xref"
HREF="ch14_11.htm"
TITLE="Finding (Anyone's) Home Directory, Quickly "
>14.11</A
></TD
></TR
><TR
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><TD
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>~<CODE
CLASS="replaceable"
><I
>user</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, ksh, bash</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Home directory of <CODE
CLASS="replaceable"
><I
>user</I
></CODE
>.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch14_11.htm"
TITLE="Finding (Anyone's) Home Directory, Quickly "
>14.11</A
></TD
></TR
><TR
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><TD
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>!</TD
><TD
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ROWSPAN="1"
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>csh, bash</TD
><TD
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ROWSPAN="1"
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>Command history.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch11_02.htm"
TITLE="History in a Nutshell "
>11.2</A
></TD
></TR
><TR
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><TD
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>-</TD
><TD
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>Programs</TD
><TD
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>Start of optional argument.</TD
><TD
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ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch08_05.htm"
TITLE="Command-Line Evaluation "
>8.5</A
></TD
></TR
><TR
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><TD
CLASS="entry"
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>-</TD
><TD
CLASS="entry"
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>Programs</TD
><TD
CLASS="entry"
ROWSPAN="1"
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><P
CLASS="para"
>Read standard input. (Only certain programs.)</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_13.htm"
TITLE='The "Filename&quot; - '
>13.13</A
></TD
></TR
><TR
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><TD
CLASS="entry"
ROWSPAN="1"
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>$#</TD
><TD
CLASS="entry"
ROWSPAN="1"
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>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Number of arguments to script.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_15.htm"
TITLE="Handling Command-Line Arguments in Shell Scripts "
>44.15</A
></TD
></TR
><TR
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><TD
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>&quot;$@&quot;</TD
><TD
CLASS="entry"
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>sh</TD
><TD
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>Original arguments to script.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_15.htm"
TITLE="Handling Command-Line Arguments in Shell Scripts "
>44.15</A
></TD
></TR
><TR
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><TD
CLASS="entry"
ROWSPAN="1"
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>$*</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Arguments to script.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_15.htm"
TITLE="Handling Command-Line Arguments in Shell Scripts "
>44.15</A
></TD
></TR
><TR
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VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
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>$-</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Flags set in shell.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch02_11.htm"
TITLE="Faster ksh and bash Startup with $- Test "
>2.11</A
></TD
></TR
><TR
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><TD
CLASS="entry"
ROWSPAN="1"
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>$?</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Status of previous command.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_07.htm"
TITLE="Exit Status of UNIX Processes "
>44.7</A
></TD
></TR
><TR
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VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>$$</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Process identification number.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch08_14.htm"
TITLE="Bourne Shell Quoting "
>8.14</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>$!</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Process identification number of last background job.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch07_12.htm"
TITLE="External Commands Send Signals to Set Variables "
>7.12</A
></TD
></TR
><TR
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VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>$&lt;</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Read input from terminal.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch09_11.htm"
TITLE="Repeating a Command with a foreach Loop "
>9.11</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>cmd1</I
></CODE
> &amp;&amp; <CODE
CLASS="replaceable"
><I
>cmd2</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Execute <CODE
CLASS="replaceable"
><I
>cmd2</I
></CODE
> if <CODE
CLASS="replaceable"
><I
>cmd1</I
></CODE
> succeeds.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_09.htm"
TITLE="Testing Your Success "
>44.9</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>cmd1</I
></CODE
> || <CODE
CLASS="replaceable"
><I
>cmd2</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Execute <CODE
CLASS="replaceable"
><I
>cmd2</I
></CODE
> if <CODE
CLASS="replaceable"
><I
>cmd1</I
></CODE
> fails.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_09.htm"
TITLE="Testing Your Success "
>44.9</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>$(..)</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>ksh, bash</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Command substitution.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
><A
CLASS="xref"
HREF="ch45_31.htm"
TITLE="Nested Command Substitution "
>45.31</A
>,
<A
CLASS="xref"
HREF="ch09_16.htm"
TITLE="Command Substitution "
>9.16</A
></P
></TD
></TR
><TR
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><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>((..))</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>ksh, bash</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Arithmetic evaluation.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>\. <CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Execute commands from <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>
in this shell.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_23.htm"
TITLE="Reading Files with the . and source Commands "
>44.23</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>:</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Evaluate arguments, return true.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_09.htm"
TITLE='The Unappreciated Bourne Shell  ":&quot; Operator'
>45.9</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>:</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Separate values in paths.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
><A
CLASS="xref"
HREF="ch06_04.htm"
TITLE="The PATH Environment Variable "
>6.4</A
>,
<A
CLASS="xref"
HREF="ch14_05.htm"
TITLE="Saving Time When You Change Directories: cdpath "
>14.5</A
>,
<A
CLASS="xref"
HREF="ch21_08.htm"
TITLE="The MAILCHECK and mail Variables Check More than Mail"
>21.8</A
></P
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>:</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Variable modifier.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch09_06.htm"
TITLE="String Editing (Colon) Operators "
>9.6</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>[]</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Match range of characters.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
><A
CLASS="xref"
HREF="ch01_16.htm"
TITLE="Wildcards "
>1.16</A
>,
<A
CLASS="xref"
HREF="ch15_02.htm"
TITLE="Filename Wildcards in a Nutshell "
>15.2</A
></P
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>[]</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Test.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch44_20.htm"
TITLE="test: Testing Files and Strings "
>44.20</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>%<CODE
CLASS="replaceable"
><I
>job</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, ksh, bash</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Identify job number.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch12_01.htm#UPT-ART-0439"
TITLE="Job Control: Work Faster, Stop Runaway Jobs "
>12.1</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>(<CODE
CLASS="replaceable"
><I
>cmd</I
></CODE
>;<CODE
CLASS="replaceable"
><I
>cmd</I
></CODE
>)</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"