ch08_19.htm

the unix power tools

>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Run <CODE
CLASS="replaceable"
><I
>cmd</I
></CODE
><CODE
CLASS="literal"
>;</CODE
><CODE
CLASS="replaceable"
><I
>cmd</I
></CODE
> in a subshell.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_07.htm"
TITLE="The () Subshell Operators "
>13.7</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>{}</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, bash</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>In-line expansions.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
><A
CLASS="xref"
HREF="ch09_05.htm"
TITLE="Build Strings with {&nbsp;} "
>9.5</A
></P
></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"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Like <CODE
CLASS="literal"
>(</CODE
><CODE
CLASS="replaceable"
><I
>cmd</I
></CODE
><CODE
CLASS="literal"
>;</CODE
><CODE
CLASS="replaceable"
><I
>cmd</I
></CODE
><CODE
CLASS="literal"
>)</CODE
> without a subshell.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_08.htm"
TITLE="Using {list} to Group Bourne Shell Commands "
>13.8</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;<CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Redirect standard output.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_01.htm#UPT-ART-1023"
TITLE="Using Standard Input and Output"
>13.1</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;&gt;<CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Append standard output.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_01.htm#UPT-ART-1023"
TITLE="Using Standard Input and Output"
>13.1</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&lt;<CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Redirect standard input.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_01.htm#UPT-ART-1023"
TITLE="Using Standard Input and Output"
>13.1</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&lt;&lt;<CODE
CLASS="replaceable"
><I
>word</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Read until <CODE
CLASS="replaceable"
><I
>word</I
></CODE
>, do command and variable substitution.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
><A
CLASS="xref"
HREF="ch08_18.htm"
TITLE="Here Documents "
>8.18</A
>,
<A
CLASS="xref"
HREF="ch09_14.htm"
TITLE="Using Here Documents for Form Letters, etc. "
>9.14</A
></P
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&lt;&lt;\<CODE
CLASS="replaceable"
><I
>word</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh, sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Read until <CODE
CLASS="replaceable"
><I
>word</I
></CODE
>, no substitution.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch08_18.htm"
TITLE="Here Documents "
>8.18</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&lt;&lt;-<CODE
CLASS="replaceable"
><I
>word</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Read until <CODE
CLASS="replaceable"
><I
>word</I
></CODE
>, ignoring leading TABs.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch08_18.htm"
TITLE="Here Documents "
>8.18</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;&gt;!&nbsp;<CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Append to <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>, even if <EM
CLASS="emphasis"
>noclobber</EM
> 
set and <CODE
CLASS="replaceable"
><I
>file</I
></CODE
> doesn't exist.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_06.htm"
TITLE="Safe I/O Redirection with noclobber "
>13.6</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;!&nbsp;<CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Output to <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>, even if <EM
CLASS="emphasis"
>noclobber</EM
> 
set and <CODE
CLASS="replaceable"
><I
>file</I
></CODE
> exists.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_06.htm"
TITLE="Safe I/O Redirection with noclobber "
>13.6</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;|&nbsp;<CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>ksh, bash</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Output to <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>, even if <EM
CLASS="emphasis"
>noclobber</EM
> 
set and <CODE
CLASS="replaceable"
><I
>file</I
></CODE
> exists.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_06.htm"
TITLE="Safe I/O Redirection with noclobber "
>13.6</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;&amp; <CODE
CLASS="replaceable"
><I
>file</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>csh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Redirect standard output and standard error 
to <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch13_05.htm"
TITLE="Redirection in C Shell: Capture Errors, Too? "
>13.5</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>m</I
></CODE
>&gt; <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"
>Redirect output file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
> to 
<CODE
CLASS="replaceable"
><I
>file</I
></CODE
>.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_21.htm"
TITLE="n&gt;&amp;m: Swap Standard Output and Standard Error "
>45.21</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>m</I
></CODE
>&gt;&gt; <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"
>Append output file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
> to <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>.</P
></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
>m</I
></CODE
>&lt; <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"
>Redirect input file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
> from <CODE
CLASS="replaceable"
><I
>file</I
></CODE
>.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&lt;&amp;<CODE
CLASS="replaceable"
><I
>m</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Take standard input from file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
>.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&lt;&amp;-</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Close standard input.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_10.htm"
TITLE="Removing a File Once It's Opened&nbsp;- for Security and Easy Cleanup"
>45.10</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;&amp;<CODE
CLASS="replaceable"
><I
>m</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Use file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
> as standard output.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_21.htm"
TITLE="n&gt;&amp;m: Swap Standard Output and Standard Error "
>45.21</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>&gt;&amp;-</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Close standard output.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_21.htm"
TITLE="n&gt;&amp;m: Swap Standard Output and Standard Error "
>45.21</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>m</I
></CODE
>&lt;&amp;<CODE
CLASS="replaceable"
><I
>n</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Connect input file descriptor <CODE
CLASS="replaceable"
><I
>n</I
></CODE
> to file 
descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
>.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_22.htm"
TITLE="Handling Files Line-by-Line "
>45.22</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>m</I
></CODE
>&lt;&amp;-</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Close input file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
>.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_21.htm"
TITLE="n&gt;&amp;m: Swap Standard Output and Standard Error "
>45.21</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>n</I
></CODE
>&gt;&amp;<CODE
CLASS="replaceable"
><I
>m</I
></CODE
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><P
CLASS="para"
>Connect output file descriptor <CODE
CLASS="replaceable"
><I
>n</I
></CODE
> to file 
descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
>.</P
></TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_21.htm"
TITLE="n&gt;&amp;m: Swap Standard Output and Standard Error "
>45.21</A
></TD
></TR
><TR
CLASS="row"
VALIGN="TOP"
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><CODE
CLASS="replaceable"
><I
>m</I
></CODE
>&gt;&amp;-</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>sh</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
>Close output file descriptor <CODE
CLASS="replaceable"
><I
>m</I
></CODE
>.</TD
><TD
CLASS="entry"
ROWSPAN="1"
COLSPAN="1"
><A
CLASS="xref"
HREF="ch45_21.htm"
TITLE="n&gt;&amp;m: Swap Standard Output and Standard Error "
>45.21</A
></TD
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><P
CLASS="SECT1INFO"
>- <SPAN
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>BB</SPAN
>, <SPAN
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