 
			| GNU/Linux | CentOS 5.4 | |
|  | sleep(3) |  | 
sleep − Sleep for the specified number of seconds
#include <unistd.h>
unsigned int sleep(unsigned int seconds);
sleep() makes the current process sleep until seconds seconds have elapsed or a signal arrives which is not ignored.
Zero if the requested time has elapsed, or the number of seconds left to sleep.
POSIX.1-2001.
sleep() may be implemented using SIGALRM; mixing calls to alarm() and sleep() is a bad idea.
Using longjmp() from a signal handler or modifying the handling of SIGALRM while sleeping will cause undefined results.
alarm(2), signal(2)
|  | sleep(3) |  |