sleep - sleep for a specified number of seconds
unsigned int sleep(unsigned int seconds);
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.
Zero if the requested time has elapsed, or the number of seconds left to sleep, if the call was interrupted by a signal handler.
For an explanation of the terms used in this section, see attributes(7).
|Interface ||Attribute ||Value |
|sleep () ||Thread safety ||MT-Unsafe sig:SIGCHLD/linux |
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.
Using longjmp(3) from a signal handler or modifying the handling of SIGALRM while sleeping will cause undefined results.