usleep

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



NAME
       usleep - suspend execution for microsecond intervals

SYNOPSIS
       /* BSD version */
       #include <unistd.h>

       void usleep(unsigned long usec);

       /* SUSv2 version */
       #define _XOPEN_SOURCE 500
       #include <unistd.h>

       int usleep(useconds_t usec);

DESCRIPTION
       The  usleep()  function	suspends execution of the calling process 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
       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 proto-
       type used by glibc 2.2.2.  Only the EINVAL error return is  documented
       by SUSv2.

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);

       This type is defined by <sys/types.h> included by <unistd.h> but glibc
       defines it only when _XOPEN_SOURCE has a value not less than  500,  or
       both _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED are defined.

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       This function is obsolete.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



				  2003-07-23			    USLEEP(3)