169 lines
3.7 KiB
HTML
169 lines
3.7 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of FORK</TITLE>
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</HEAD><BODY>
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<H1>FORK</H1>
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Section: GNU Awk Extension Modules (3am)<BR>Updated: Feb 02 2018<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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fork, wait, waitpid - basic process management
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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@load "fork"
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<P>
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pid = fork()
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<P>
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ret = waitpid(pid)
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<P>
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ret = wait();
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<I>fork</I>
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extension adds three functions, as follows.
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<DL COMPACT>
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<DT id="1"><B>fork()</B>
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<DD>
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This function creates a new process. The return value is the zero
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in the child and the process-id number of the child in the parent,
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or -1 upon error. In the latter case,
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<B>ERRNO</B>
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indicates the problem.
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In the child, <B>PROCINFO["pid"]</B> and <B>PROCINFO["ppid"]</B>
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are updated to reflect the correct values.
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<DT id="2"><B>waitpid()</B>
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<DD>
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This function takes a numeric argument, which is the process-id to
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wait for. The return value is that of the
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<I><A HREF="/cgi-bin/man/man2html?2+waitpid">waitpid</A></I>(2)
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system call.
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<DT id="3"><B>wait()</B>
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<DD>
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This function waits for the first child to die.
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The return value is that of the
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<I><A HREF="/cgi-bin/man/man2html?2+wait">wait</A></I>(2)
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system call.
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</DL>
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<A NAME="lbAE"> </A>
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<H2>BUGS</H2>
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There is no corresponding
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<B>exec()</B>
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function.
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<P>
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The interfaces could be enhanced to provide more facilities,
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including pulling out the various bits of the return status.
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<A NAME="lbAF"> </A>
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<H2>EXAMPLE</H2>
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<PRE>
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@load "fork"
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...
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if ((pid = fork()) == 0)
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print "hello from the child"
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else
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print "hello from the parent"
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</PRE>
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<I>GAWK: Effective AWK Programming</I>,
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<I>filefuncs</I>(3am),
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<I>fnmatch</I>(3am),
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<I>inplace</I>(3am),
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<I>ordchr</I>(3am),
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<I>readdir</I>(3am),
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<I>readfile</I>(3am),
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<I>revoutput</I>(3am),
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<I>rwarray</I>(3am),
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<I>time</I>(3am).
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<P>
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<I><A HREF="/cgi-bin/man/man2html?2+fork">fork</A></I>(2),
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<I><A HREF="/cgi-bin/man/man2html?2+wait">wait</A></I>(2),
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<I><A HREF="/cgi-bin/man/man2html?2+waitpid">waitpid</A></I>(2).
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<A NAME="lbAH"> </A>
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<H2>AUTHOR</H2>
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Arnold Robbins,
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<B><A HREF="mailto:arnold@skeeve.com">arnold@skeeve.com</A></B>.
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<A NAME="lbAI"> </A>
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<H2>COPYING PERMISSIONS</H2>
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Copyright © 2012, 2013, 2018,
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Free Software Foundation, Inc.
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<P>
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Permission is granted to make and distribute verbatim copies of
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this manual page provided the copyright notice and this permission
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notice are preserved on all copies.
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<P>
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Permission is granted to copy and distribute modified versions of this
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manual page under the conditions for verbatim copying, provided that
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the entire resulting derived work is distributed under the terms of a
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permission notice identical to this one.
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<P>
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Permission is granted to copy and distribute translations of this
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manual page into another language, under the above conditions for
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modified versions, except that this permission notice may be stated in
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a translation approved by the Foundation.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="4"><A HREF="#lbAB">NAME</A><DD>
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<DT id="5"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="6"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="7"><A HREF="#lbAE">BUGS</A><DD>
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<DT id="8"><A HREF="#lbAF">EXAMPLE</A><DD>
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<DT id="9"><A HREF="#lbAG">SEE ALSO</A><DD>
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<DT id="10"><A HREF="#lbAH">AUTHOR</A><DD>
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<DT id="11"><A HREF="#lbAI">COPYING PERMISSIONS</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:43 GMT, March 31, 2021
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</BODY>
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</HTML>
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