mirror of https://github.com/mkerrisk/man-pages
93 lines
2.6 KiB
Groff
93 lines
2.6 KiB
Groff
.\" Copyright (c) 1993 by Thomas Koenig (ig25@rz.uni-karlsruhe.de)
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.\"
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.\" %%%LICENSE_START(VERBATIM)
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" 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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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\" %%%LICENSE_END
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.\"
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.\" Modified Sat Jul 24 18:16:02 1993 by Rik Faith (faith@cs.unc.edu)
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.TH SLEEP 3 2017-09-15 "GNU" "Linux Programmer's Manual"
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.SH NAME
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sleep \- sleep for a specified number of seconds
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.SH SYNOPSIS
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.nf
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.B #include <unistd.h>
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.PP
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.BI "unsigned int sleep(unsigned int " "seconds" );
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.fi
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.SH DESCRIPTION
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.BR sleep ()
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causes the calling thread to sleep either until
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the number of real-time seconds specified in
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.I seconds
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have elapsed or until a signal arrives which is not ignored.
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.SH RETURN VALUE
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Zero if the requested time has elapsed,
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or the number of seconds left to sleep,
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if the call was interrupted by a signal handler.
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.SH ATTRIBUTES
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For an explanation of the terms used in this section, see
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.BR attributes (7).
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.TS
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allbox;
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lb lb lbw27
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l l l.
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Interface Attribute Value
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T{
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.BR sleep ()
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T} Thread safety MT-Unsafe sig:SIGCHLD/linux
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.TE
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.sp 1
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.SH CONFORMING TO
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POSIX.1-2001, POSIX.1-2008.
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.SH NOTES
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On Linux,
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.BR sleep ()
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is implemented via
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.BR nanosleep (2).
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See the
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.BR nanosleep (2)
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man page for a discussion of the clock used.
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.SS Portability notes
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On some systems,
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.BR sleep ()
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may be implemented using
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.BR alarm (2)
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and
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.BR SIGALRM
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(POSIX.1 permits this);
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mixing calls to
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.BR alarm (2)
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and
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.BR sleep ()
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is a bad idea.
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.PP
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Using
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.BR longjmp (3)
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from a signal handler or modifying the handling of
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.B SIGALRM
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while sleeping will cause undefined results.
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.SH SEE ALSO
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.BR sleep (1),
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.BR alarm (2),
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.BR nanosleep (2),
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.BR signal (2),
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.BR signal (7)
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