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  length­
       ened  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   This function is obsolete.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)


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