235 lines
5.6 KiB
HTML
235 lines
5.6 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 USLEEP</TITLE>
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</HEAD><BODY>
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<H1>USLEEP</H1>
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Section: Linux Programmer's Manual (3)<BR>Updated: 2017-09-15<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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usleep - suspend execution for microsecond intervals
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<PRE>
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<B>#include <<A HREF="file:///usr/include/unistd.h">unistd.h</A>></B>
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<B>int usleep(useconds_t </B><I>usec</I><B>);</B>
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</PRE>
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<P>
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Feature Test Macro Requirements for glibc (see
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<B><A HREF="/cgi-bin/man/man2html?7+feature_test_macros">feature_test_macros</A></B>(7)):
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<P>
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<B>usleep</B>():
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<DL COMPACT><DT id="1"><DD>
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<DL COMPACT>
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<DT id="2">Since glibc 2.12:<DD>
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<PRE>
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(_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
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|| /* Glibc since 2.19: */ _DEFAULT_SOURCE
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|| /* Glibc versions <= 2.19: */ _BSD_SOURCE
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<DT id="3"></PRE>
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<DD>
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Before glibc 2.12:
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_BSD_SOURCE || _XOPEN_SOURCE >= 500
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</DL>
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</DL>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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The
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<B>usleep</B>()
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function suspends execution of the calling thread for
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(at least) <I>usec</I> microseconds.
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The sleep may be lengthened slightly
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by any system activity or by the time spent processing the call or by the
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granularity of system timers.
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<A NAME="lbAE"> </A>
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<H2>RETURN VALUE</H2>
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The
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<B>usleep</B>()
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function returns 0 on success.
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On error, -1 is returned, with
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<I>errno</I>
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set to indicate the cause of the error.
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<A NAME="lbAF"> </A>
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<H2>ERRORS</H2>
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<DL COMPACT>
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<DT id="4"><B>EINTR</B>
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<DD>
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Interrupted by a signal; see
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<B><A HREF="/cgi-bin/man/man2html?7+signal">signal</A></B>(7).
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<DT id="5"><B>EINVAL</B>
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<DD>
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<I>usec</I> is greater than or equal to 1000000.
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(On systems where that is considered an error.)
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</DL>
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<A NAME="lbAG"> </A>
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<H2>ATTRIBUTES</H2>
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For an explanation of the terms used in this section, see
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<B><A HREF="/cgi-bin/man/man2html?7+attributes">attributes</A></B>(7).
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<TABLE BORDER>
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<TR VALIGN=top><TD><B>Interface</B></TD><TD><B>Attribute</B></TD><TD><B>Value</B><BR></TD></TR>
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<TR VALIGN=top><TD>
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<B>usleep</B>()
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</TD><TD>Thread safety</TD><TD>MT-Safe<BR></TD></TR>
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</TABLE>
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<A NAME="lbAH"> </A>
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<H2>CONFORMING TO</H2>
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4.3BSD, POSIX.1-2001.
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POSIX.1-2001 declares this function obsolete; use
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<B><A HREF="/cgi-bin/man/man2html?2+nanosleep">nanosleep</A></B>(2)
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instead.
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POSIX.1-2008 removes the specification of
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<B>usleep</B>().
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<P>
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On the original BSD implementation,
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and in glibc before version 2.2.2, the return type of this function is
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<I>void</I>.
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The POSIX version returns
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<I>int</I>,
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and this is also the prototype used since glibc 2.2.2.
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<P>
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Only the
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<B>EINVAL</B>
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error return is documented by SUSv2 and POSIX.1-2001.
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<A NAME="lbAI"> </A>
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<H2>NOTES</H2>
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The type
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<I>useconds_t</I>
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is an unsigned integer type capable of holding integers
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in the range [0,1000000].
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Programs will be more portable
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if they never mention this type explicitly.
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Use
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<P>
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#include <<A HREF="file:///usr/include/unistd.h">unistd.h</A>>
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...
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<BR> unsigned int usecs;
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...
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<BR> usleep(usecs);
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<P>
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The interaction of this function with the
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<B>SIGALRM</B>
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signal, and with other timer functions such as
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<B><A HREF="/cgi-bin/man/man2html?2+alarm">alarm</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+sleep">sleep</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?2+nanosleep">nanosleep</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+setitimer">setitimer</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+timer_create">timer_create</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+timer_delete">timer_delete</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+timer_getoverrun">timer_getoverrun</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+timer_gettime">timer_gettime</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+timer_settime">timer_settime</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+ualarm">ualarm</A></B>(3)
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is unspecified.
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<A NAME="lbAJ"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?2+alarm">alarm</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+getitimer">getitimer</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+nanosleep">nanosleep</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+select">select</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?2+setitimer">setitimer</A></B>(2),
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<B><A HREF="/cgi-bin/man/man2html?3+sleep">sleep</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?3+ualarm">ualarm</A></B>(3),
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<B><A HREF="/cgi-bin/man/man2html?7+time">time</A></B>(7)
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<A NAME="lbAK"> </A>
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<H2>COLOPHON</H2>
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This page is part of release 5.05 of the Linux
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<I>man-pages</I>
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project.
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A description of the project,
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information about reporting bugs,
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and the latest version of this page,
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can be found at
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<A HREF="https://www.kernel.org/doc/man-pages/.">https://www.kernel.org/doc/man-pages/.</A>
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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="6"><A HREF="#lbAB">NAME</A><DD>
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<DT id="7"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="8"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="9"><A HREF="#lbAE">RETURN VALUE</A><DD>
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<DT id="10"><A HREF="#lbAF">ERRORS</A><DD>
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<DT id="11"><A HREF="#lbAG">ATTRIBUTES</A><DD>
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<DT id="12"><A HREF="#lbAH">CONFORMING TO</A><DD>
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<DT id="13"><A HREF="#lbAI">NOTES</A><DD>
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<DT id="14"><A HREF="#lbAJ">SEE ALSO</A><DD>
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<DT id="15"><A HREF="#lbAK">COLOPHON</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: 00:05:59 GMT, March 31, 2021
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</BODY>
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</HTML>
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