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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(): _BSD_SOURCE || _XOPEN_SOURCE >= 500

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

       0 on success, -1 on error.

ERRORS

       EINTR  Interrupted by a signal.

       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.

       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.

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(3),  timer_delete(3),  timer_getoverrun(3),
       timer_gettime(3), timer_settime(3), ualarm(3) is unspecified.

SEE ALSO

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

COLOPHON

       This page is part of release 2.77 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/.

                                  2007-07-26                         USLEEP(3)