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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head><!-- Copyright 1997 The Open Group, All Rights Reserved --><title>fg</title></head><body bgcolor=white><center><font size=2>The Single UNIX ® Specification, Version 2<br>Copyright © 1997 The Open Group</font></center><hr size=2 noshade><h4><a name = "tag_001_014_681"> </a>NAME</h4><blockquote>fg - run jobs in the foreground</blockquote><h4><a name = "tag_001_014_682"> </a>SYNOPSIS</h4><blockquote><pre><code>fg <b>[</b><i>job_id</i><b>]</b></code></pre></blockquote><h4><a name = "tag_001_014_683"> </a>DESCRIPTION</h4><blockquote>If job control is enabled (see the description of<i>set</i><b>-m</b>),the<i>fg</i>utility will move a background jobfrom the current environment (see<xref href=shexenv><a href="chap2.html#tag_001_012">Shell Execution Environment</a></xref>)into the foreground.<p>Using<i>fg</i>to place a job into the foreground will remove its process IDfrom the list of those "known in the current shell execution environment";see<xref href=asyncl><a href="chap2.html#tag_001_009_003">Lists</a></xref>.</blockquote><h4><a name = "tag_001_014_684"> </a>OPTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_685"> </a>OPERANDS</h4><blockquote>The following operand is supported:<dl compact><dt><i>job_id</i><dd>Specify the job to be run as a foreground job.If no<i>job_id</i>operand is given,the<i>job_id</i>for the job that was mostrecently suspended, placed in the background or run as a background jobwill be used.The format of<i>job_id</i>is described in the entry for<b>job control job ID</b>inthe <b>XBD</b> specification, <a href="../xbd/glossary.html"><b>Glossary</b> </a> .</dl></blockquote><h4><a name = "tag_001_014_686"> </a>STDIN</h4><blockquote>Not used.</blockquote><h4><a name = "tag_001_014_687"> </a>INPUT FILES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_688"> </a>ENVIRONMENT VARIABLES</h4><blockquote>The following environment variables affect the execution of<i>fg</i>:<dl compact><dt><i>LANG</i><dd>Provide a default value for the internationalisation variablesthat are unset or null.If<i>LANG</i>is unset or null, the corresponding value from theimplementation-dependent default locale will be used.If any of the internationalisation variables contains an invalid setting, theutility will behave as if none of the variables had been defined.<dt><i>LC_ALL</i><dd>If set to a non-empty string value,override the values of all the other internationalisation variables.<dt><i>LC_CTYPE</i><dd>Determine thelocale for the interpretation of sequences of bytes of text data ascharacters (for example, single- as opposed to multi-byte charactersin arguments).<dt><i>LC_MESSAGES</i><dd>Determine the locale that should be used to affectthe format and contents of diagnosticmessages written to standard error.<dt><i>NLSPATH</i><dd>Determine the location of message cataloguesfor the processing of<i>LC_MESSAGES .</i></dl></blockquote><h4><a name = "tag_001_014_689"> </a>ASYNCHRONOUS EVENTS</h4><blockquote>Default.</blockquote><h4><a name = "tag_001_014_690"> </a>STDOUT</h4><blockquote>The<i>fg</i>utility writes the command line of the job to standard outputin the following format:<p><code><tt>"%s\n"</tt>, <<i>command</i>></code><p></blockquote><h4><a name = "tag_001_014_691"> </a>STDERR</h4><blockquote>Used only for diagnostic messages.</blockquote><h4><a name = "tag_001_014_692"> </a>OUTPUT FILES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_693"> </a>EXTENDED DESCRIPTION</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_694"> </a>EXIT STATUS</h4><blockquote>The following exit values are returned:<dl compact><dt>0<dd>Successful completion.<dt>>0<dd>An error occurred.</dl></blockquote><h4><a name = "tag_001_014_695"> </a>CONSEQUENCES OF ERRORS</h4><blockquote>If job control is disabled, the<i>fg</i>utility will exit with an errorand no job will be placed in the foreground.</blockquote><h4><a name = "tag_001_014_696"> </a>APPLICATION USAGE</h4><blockquote>The<i>fg</i>utility will not work as expected when itis operating in its own utility execution environmentbecause that environment will have no applicable jobsto manipulate.See the APPLICATION USAGE section for<i><a href="bg.html">bg</a></i>.For this reason,<i>fg</i>is generally implemented as a shell regular built-in.</blockquote><h4><a name = "tag_001_014_697"> </a>EXAMPLES</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_698"> </a>FUTURE DIRECTIONS</h4><blockquote>None.</blockquote><h4><a name = "tag_001_014_699"> </a>SEE ALSO</h4><blockquote><i><a href="bg.html">bg</a></i>,<i><a href="kill.html">kill</a></i>,<i><a href="jobs.html">jobs</a></i>,<i><a href="wait.html">wait</a></i>.</blockquote><hr size=2 noshade><center><font size=2>UNIX ® is a registered Trademark of The Open Group.<br>Copyright © 1997 The Open Group<br> [ <a href="../index.html">Main Index</a> | <a href="../xshix.html">XSH</a> | <a href="../xcuix.html">XCU</a> | <a href="../xbdix.html">XBD</a> | <a href="../cursesix.html">XCURSES</a> | <a href="../xnsix.html">XNS</a> ]</font></center><hr size=2 noshade></body></html>⌨️ 快捷键说明
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