sleep(3) — Linux manual page

NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ATTRIBUTES | VERSIONS | STANDARDS | HISTORY | CAVEATS | SEE ALSO | COLOPHON

sleep(3)                Library Functions Manual                sleep(3)

NAME         top

       sleep - sleep for a specified number of seconds

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <unistd.h>

       unsigned int sleep(unsigned int seconds);

DESCRIPTION         top

       sleep() causes the calling thread to sleep either until the
       number of real-time seconds specified in seconds have elapsed or
       until a signal arrives which is not ignored.

RETURN VALUE         top

       Zero if the requested time has elapsed, or the number of seconds
       left to sleep, if the call was interrupted by a signal handler.

ATTRIBUTES         top

       For an explanation of the terms used in this section, see
       attributes(7).
       ┌─────────────────┬───────────────┬─────────────────────────────┐
       │ Interface       Attribute     Value                       │
       ├─────────────────┼───────────────┼─────────────────────────────┤
       │ sleep()         │ Thread safety │ MT-Unsafe sig:SIGCHLD/linux │
       └─────────────────┴───────────────┴─────────────────────────────┘

VERSIONS         top

       On Linux, sleep() is implemented via nanosleep(2).  See the
       nanosleep(2) man page for a discussion of the clock used.

       On some systems, sleep() may be implemented using alarm(2) and
       SIGALRM (POSIX.1 permits this); mixing calls to alarm(2) and
       sleep() is a bad idea.

STANDARDS         top

       POSIX.1-2008.

HISTORY         top

       POSIX.1-2001.

CAVEATS         top

       Using longjmp(3) from a signal handler or modifying the handling
       of SIGALRM while sleeping will cause undefined results.

SEE ALSO         top

       sleep(1), alarm(2), nanosleep(2), signal(2), signal(7)

COLOPHON         top

       This page is part of the man-pages (Linux kernel and C library
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       ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
       This page was obtained from the tarball man-pages-6.9.1.tar.gz
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       [email protected]

Linux man-pages 6.9.1          2024-05-02                       sleep(3)

Pages that refer to this page: sleep(1)alarm(2)clock_nanosleep(2)getitimer(2)nanosleep(2)ualarm(3)usleep(3)signal(7)signal-safety(7)time(7)