243 lines
8.0 KiB
HTML
243 lines
8.0 KiB
HTML
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<!-- Copyright (c) 2001 The Open Group, All Rights Reserved -->
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<title>fg</title>
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<body bgcolor="white">
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<basefont size="3"> <a name="fg"></a> <a name="tag_04_53"></a><!-- fg -->
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<!--header start-->
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<center><font size="2">The Open Group Base Specifications Issue 6<br>
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IEEE Std 1003.1-2001<br>
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Copyright © 2001 The IEEE and The Open Group, All Rights reserved.</font></center>
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<!--header end-->
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<hr size="2" noshade>
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<h4><a name="tag_04_53_01"></a>NAME</h4>
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<blockquote>fg - run jobs in the foreground</blockquote>
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<h4><a name="tag_04_53_02"></a>SYNOPSIS</h4>
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<blockquote class="synopsis">
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<div class="box"><code><tt><sup>[<a href="javascript:open_code('UP')">UP</a>]</sup> <img src="../images/opt-start.gif" alt=
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"[Option Start]" border="0"> fg</tt> <b>[</b><i>job_id</i><b>]</b><tt><img src="../images/opt-end.gif" alt="[Option End]" border=
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"0"></tt></code></div>
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</blockquote>
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<h4><a name="tag_04_53_03"></a>DESCRIPTION</h4>
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<blockquote>
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<p>If job control is enabled (see the description of <a href="../utilities/set.html"><i>set</i></a> <b>-m</b>), the
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<i>fg</i> utility shall move a background job from the current environment (see <a href="xcu_chap02.html#tag_02_12"><i>Shell
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Execution Environment</i></a> ) into the foreground.</p>
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<p>Using <i>fg</i> to place a job into the foreground shall remove its process ID from the list of those "known in the current
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shell execution environment''; see <a href="xcu_chap02.html#tag_02_09_03_02"><i>Asynchronous Lists</i></a> .</p>
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</blockquote>
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<h4><a name="tag_04_53_04"></a>OPTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_53_05"></a>OPERANDS</h4>
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<blockquote>
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<p>The following operand shall be supported:</p>
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<dl compact>
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<dt><i>job_id</i></dt>
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<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
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most recently suspended, placed in the background, or run as a background job shall be used. The format of <i>job_id</i> is
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described in the Base Definitions volume of IEEE Std 1003.1-2001, <a href=
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"../basedefs/xbd_chap03.html#tag_03_203">Section 3.203, Job Control Job ID</a>.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_53_06"></a>STDIN</h4>
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<blockquote>
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<p>Not used.</p>
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</blockquote>
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<h4><a name="tag_04_53_07"></a>INPUT FILES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_53_08"></a>ENVIRONMENT VARIABLES</h4>
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<blockquote>
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<p>The following environment variables shall affect the execution of <i>fg</i>:</p>
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<dl compact>
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<dt><i>LANG</i></dt>
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<dd>Provide a default value for the internationalization variables that are unset or null. (See the Base Definitions volume of
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IEEE Std 1003.1-2001, <a href="../basedefs/xbd_chap08.html#tag_08_02">Section 8.2, Internationalization Variables</a> for
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the precedence of internationalization variables used to determine the values of locale categories.)</dd>
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<dt><i>LC_ALL</i></dt>
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<dd>If set to a non-empty string value, override the values of all the other internationalization variables.</dd>
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<dt><i>LC_CTYPE</i></dt>
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<dd>Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as
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opposed to multi-byte characters in arguments).</dd>
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<dt><i>LC_MESSAGES</i></dt>
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<dd>Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard
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error.</dd>
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<dt><i>NLSPATH</i></dt>
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<dd><sup>[<a href="javascript:open_code('XSI')">XSI</a>]</sup> <img src="../images/opt-start.gif" alt="[Option Start]" border="0">
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Determine the location of message catalogs for the processing of <i>LC_MESSAGES .</i> <img src="../images/opt-end.gif" alt=
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"[Option End]" border="0"></dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_53_09"></a>ASYNCHRONOUS EVENTS</h4>
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<blockquote>
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<p>Default.</p>
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</blockquote>
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<h4><a name="tag_04_53_10"></a>STDOUT</h4>
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<blockquote>
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<p>The <i>fg</i> utility shall write the command line of the job to standard output in the following format:</p>
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<pre>
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<tt>"%s\n", <</tt><i>command</i><tt>>
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</tt>
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</pre>
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</blockquote>
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<h4><a name="tag_04_53_11"></a>STDERR</h4>
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<blockquote>
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<p>The standard error shall be used only for diagnostic messages.</p>
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</blockquote>
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<h4><a name="tag_04_53_12"></a>OUTPUT FILES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_53_13"></a>EXTENDED DESCRIPTION</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_53_14"></a>EXIT STATUS</h4>
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<blockquote>
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<p>The following exit values shall be returned:</p>
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<dl compact>
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<dt> 0</dt>
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<dd>Successful completion.</dd>
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<dt>>0</dt>
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<dd>An error occurred.</dd>
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</dl>
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</blockquote>
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<h4><a name="tag_04_53_15"></a>CONSEQUENCES OF ERRORS</h4>
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<blockquote>
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<p>If job control is disabled, the <i>fg</i> utility shall exit with an error and no job shall be placed in the foreground.</p>
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</blockquote>
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<hr>
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<div class="box"><em>The following sections are informative.</em></div>
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<h4><a name="tag_04_53_16"></a>APPLICATION USAGE</h4>
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<blockquote>
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<p>The <i>fg</i> utility does not work as expected when it is operating in its own utility execution environment because that
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environment has no applicable jobs to manipulate. See the APPLICATION USAGE section for <a href="bg.html"><i>bg</i></a> . For this
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reason, <i>fg</i> is generally implemented as a shell regular built-in.</p>
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</blockquote>
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<h4><a name="tag_04_53_17"></a>EXAMPLES</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_53_18"></a>RATIONALE</h4>
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<blockquote>
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<p>The extensions to the shell specified in this volume of IEEE Std 1003.1-2001 have mostly been based on features
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provided by the KornShell. The job control features provided by <a href="../utilities/bg.html"><i>bg</i></a>, <i>fg</i>, and <a
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href="../utilities/jobs.html"><i>jobs</i></a> are also based on the KornShell. The standard developers examined the characteristics
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of the C shell versions of these utilities and found that differences exist. Despite widespread use of the C shell, the KornShell
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versions were selected for this volume of IEEE Std 1003.1-2001 to maintain a degree of uniformity with the rest of the
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KornShell features selected (such as the very popular command line editing features).</p>
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</blockquote>
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<h4><a name="tag_04_53_19"></a>FUTURE DIRECTIONS</h4>
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<blockquote>
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<p>None.</p>
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</blockquote>
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<h4><a name="tag_04_53_20"></a>SEE ALSO</h4>
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<blockquote>
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<p><a href="xcu_chap02.html#tag_02_09_03_02"><i>Asynchronous Lists</i></a> , <a href="xcu_chap02.html#tag_02_12"><i>Shell Execution
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Environment</i></a> , <a href="bg.html"><i>bg</i></a> , <a href="kill.html"><i>kill</i>()</a> , <a href="jobs.html"><i>jobs</i></a>
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, <a href="wait.html"><i>wait</i>()</a></p>
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</blockquote>
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<h4><a name="tag_04_53_21"></a>CHANGE HISTORY</h4>
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<blockquote>
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<p>First released in Issue 4.</p>
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</blockquote>
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<h4><a name="tag_04_53_22"></a>Issue 6</h4>
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<blockquote>
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<p>This utility is marked as part of the User Portability Utilities option.</p>
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<p>The APPLICATION USAGE section is added.</p>
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<p>The JC marking is removed from the SYNOPSIS since job control is mandatory is this issue.</p>
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</blockquote>
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<div class="box"><em>End of informative text.</em></div>
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<hr>
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<center><font size="2"><!--footer start-->
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UNIX ® is a registered Trademark of The Open Group.<br>
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POSIX ® is a registered Trademark of The IEEE.<br>
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[ <a href="../mindex.html">Main Index</a> | <a href="../basedefs/contents.html">XBD</a> | <a href=
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"../utilities/contents.html">XCU</a> | <a href="../functions/contents.html">XSH</a> | <a href="../xrat/contents.html">XRAT</a>
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]</font></center>
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