sleep(3) - Linux manual page (original) (raw)

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)](../man7/attributes.7.html).
   ┌──────────────────┬───────────────┬─────────────────────────────┐
   │ **Interface** │ **Attribute** │ **Value** │
   ├──────────────────┼───────────────┼─────────────────────────────┤
   │ **sleep**()          │ Thread safety │ MT-Unsafe sig:SIGCHLD/linux │
   └──────────────────┴───────────────┴─────────────────────────────┘

VERSIONS top

   On Linux, **sleep**() is implemented via [nanosleep(2)](../man2/nanosleep.2.html).  See the
   [nanosleep(2)](../man2/nanosleep.2.html) man page for a discussion of the clock used.

   On some systems, **sleep**() may be implemented using [alarm(2)](../man2/alarm.2.html) and
   **SIGALRM** (POSIX.1 permits this); mixing calls to [alarm(2)](../man2/alarm.2.html) and
   **sleep**() is a bad idea.

STANDARDS top

   POSIX.1-2008.

HISTORY top

   POSIX.1-2001.

CAVEATS top

   Using [longjmp(3)](../man3/longjmp.3.html) from a signal handler or modifying the handling
   of **SIGALRM** while sleeping will cause undefined results.

SEE ALSO top

   [sleep(1)](../man1/sleep.1.html), [alarm(2)](../man2/alarm.2.html), [nanosleep(2)](../man2/nanosleep.2.html), [signal(2)](../man2/signal.2.html), [signal(7)](../man7/signal.7.html)

COLOPHON top

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Linux man-pages 6.10 2024-07-23 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)