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SLEEP(3) Linux Programmer's Manual SLEEP(3)

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                       |
     +----------+---------------+-----------------------------+
     |sleep()   | 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.

SEE ALSO

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

COLOPHON

     This  page  is  part of release 4.16 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/.

GNU 2017-09-15 SLEEP(3)