sleep - Man Page

sleep for a specified number of seconds

Library

Standard C library (libc, -lc)

Synopsis

#include <unistd.h>

unsigned int sleep(unsigned int seconds);

Description

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

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

For an explanation of the terms used in this section, see attributes(7).

InterfaceAttributeValue
sleep()Thread safetyMT-Unsafe sig:SIGCHLD/linux

Versions

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

POSIX.1-2008.

History

POSIX.1-2001.

Caveats

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

See Also

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

Referenced By

aio(7), alarm(2), clock_nanosleep(2), dskutil(1), getitimer(2), libperf-sampling(7), libuv(1), nanosleep(2), OSSL_sleep.3ossl(3), pthsem(3), signal(7), signal-safety(7), sleep(1), stress-ng(1), time(7), ualarm(3), upslog(8), usleep(3).

2023-10-31 Linux man-pages 6.06