NAME
usleep - suspend execution for microsecond intervals
SYNOPSIS
#define _XOPEN_SOURCE 500 /* Or: #define _BSD_SOURCE */
#include <unistd.h>
I int usleep(useconds_t usec );
DESCRIPTION
The
R 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
R void .
The POSIX version returns
R 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
