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2017-09-15

manpages-dev

Manual pages about using GNU/Linux for development

man-pages

Linux kernel and C library user-space interface documentation

NAME

sleep - sleep for a specified number of seconds

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).
Interface Attribute Value
Thread safety MT-Unsafe sig:SIGCHLD/linux

CONFORMING TO

POSIX.1-2001, POSIX.1-2008.

NOTES

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

Portability notes

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

COLOPHON

This page is part of release 5.00 of the Linux man-pages project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https://www.kernel.org/doc/man-pages/.
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