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

NAME

       usleep - suspend execution for microsecond intervals

SYNOPSIS

       #include <unistd.h>

       int usleep(useconds_t usec);

   Feature Test Macro Requirements for glibc (see feature_test_macros(7)):

       usleep():
	   Since glibc 2.12:
	       _BSD_SOURCE ||
		   (_XOPEN_SOURCE >= 500 ||
		       _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED) &&
		   !(_POSIX_C_SOURCE >= 200809L || _XOPEN_SOURCE >= 700)
	   Before glibc 2.12:
	       _BSD_SOURCE || _XOPEN_SOURCE >= 500 || _XOPEN_SOURCE && _XOPEN_SOURCE_EXTENDED

DESCRIPTION

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

RETURN VALUE

       0 on success, -1 on error.

ERRORS

       EINTR  Interrupted by a signal; see signal(7).

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

CONFORMING TO

       4.3BSD, POSIX.1-2001.  POSIX.1-2001 declares this function obsolete; use nanosleep(2) instead.  POSIX.1-2008 removes the  specification	of
       usleep().

       On the original BSD implementation, and in glibc before version 2.2.2, the return type of this function is void.  The POSIX version returns
       int, and this is also the prototype used since glibc 2.2.2.

       Only the EINVAL error return is documented by SUSv2 and POSIX.1-2001.

NOTES

       The type useconds_t is an unsigned integer type capable of holding integers in the range [0,1000000].  Programs will be	more  portable	if
       they never mention this type explicitly.  Use

	   #include <unistd.h>
	   ...
	       unsigned int usecs;
	   ...
	       usleep(usecs);

       The  interaction  of  this  function  with  the	SIGALRM  signal,  and with other timer functions such as alarm(2), sleep(3), nanosleep(2),
       setitimer(2), timer_create(2), timer_delete(2), timer_getoverrun(2), timer_gettime(2), timer_settime(2), ualarm(3) is unspecified.

SEE ALSO

       alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), sleep(3), ualarm(3), time(7)

COLOPHON

       This page is part of release 3.44 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

								    2010-12-03								 USLEEP(3)