usleep(3)

1USLEEP(3)                  Linux Programmer's Manual                 USLEEP(3)
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NAME

6       usleep - suspend execution for microsecond intervals
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SYNOPSIS

9       #define _XOPEN_SOURCE 500     /* Or: #define _BSD_SOURCE */
10       #include <unistd.h>
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12       int usleep(useconds_t usec);
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DESCRIPTION

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

21       0 on success, -1 on error.
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ERRORS

24       EINTR  Interrupted by a signal.
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26       EINVAL usec is not smaller than 1000000.  (On  systems  where  that  is
27              considered an error.)
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CONFORMING TO

30       4.3BSD,  POSIX.1-2001.   POSIX.1-2001  declares this function obsolete;
31       use nanosleep(2) instead.
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33       On the original BSD implementation, and in glibc before version  2.2.2,
34       the  return  type  of this function is void.  The POSIX version returns
35       int, and this is also the prototype used since glibc 2.2.2.
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37       Only the EINVAL error return is documented by SUSv2.
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NOTES

40       The type useconds_t is an unsigned  integer  type  capable  of  holding
41       integers  in  the  range [0,1000000]. Programs will be more portable if
42       they never mention this type explicitly. Use
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44              #include <unistd.h>
45              ...
46                  unsigned int usecs;
47              .
48                  usleep(usecs);
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50       The interaction of this function with  the  SIGALRM  signal,  and  with
51       other   timer   functions   such   as  alarm(),  sleep(),  nanosleep(),
52       setitimer(),   timer_create(),   timer_delete(),    timer_getoverrun(),
53       timer_gettime(), timer_settime(), ualarm() is unspecified.
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