redhat man page for usleep

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

NAME
       usleep - suspend execution for microsecond intervals

SYNOPSIS
       #include <unistd.h>

       void usleep(unsigned long usec);
       int usleep(unsigned long usec); /* SUSv2 */

DESCRIPTION
       The  usleep() function suspends execution of the calling process for usec microseconds.	The sleep may be lengthened slightly by any system
       activity or by the time spent processing the call.

RETURN VALUE
       None (BSD). Or: 0 on success, -1 on error (SUSv2).

ERRORS
       EINTR  Interrupted by a signal.

       EINVAL usec is not smaller than 1000000.  (On systems where that is considered an error.)

CONFORMING TO
       BSD 4.3.  The SUSv2 version returns int, and this is also the prototype used by glibc 2.2.2.  Only the EINVAL error return is documented by
       SUSv2.

NOTES
       The  interaction of this function with SIGALRM and other timer functions such as sleep(), alarm(), setitimer(), nanosleep() is unspecified.
       This function is obsolete. Use nanosleep(2) or setitimer(2) instead.

SEE ALSO
       alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), sleep(3)

								    2001-04-02								 USLEEP(3)