usleep


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);

       description  of  the project, and information about reporting bugs, can
       be found at http://man7.org/linux/man-pages/.



                                  2010-12-03                         USLEEP(3)
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