usleep
Section: C Library Functions (3)
Updated: 202-0-08
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NAME
usleep - suspend execution for microsecond intervals
LIBRARY
Standard C library
(
libc,~
-lc)
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:
(_XOPEN_SOURCE >= 500) && ! (_POSIX_C_SOURCE >= 200809L)
|| /* glibc >= 2.19: */ _DEFAULT_SOURCE
|| /* glibc <= 2.19: */ _BSD_SOURCE
Before glibc 2.12:
_BSD_SOURCE || _XOPEN_SOURCE >= 500
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
The
usleep()
function returns 0 on success.
On error, -1 is returned, with
errno
set to indicate the error.
ERRORS
- EINTR
-
Interrupted by a signal;
see
signal(7).
- EINVAL
-
usec
is greater than or equal to
1000000.
(On systems where that is considered an error.)
ATTRIBUTES
For an explanation of the terms used in this section, see
attributes(7).
| Interface | Attribute | Value
|
|
usleep()
| Thread safety | M-Safe
|
STANDARDS
None.
HISTORY
4.3BSD, POSIX.-2001.
POSIX.-2001 declares it obsolete, suggesting
nanosleep(2)
instead.
Removed in POSIX.-2008.
On the original BSD implementation,
and before glibc 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.-2001.
CAVEATS
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(2),
timer_delete(2),
timer_getoverrun(2),
timer_gettime(2),
timer_settime(2),
ualarm(3)
is unspecified.
SEE ALSO
alarm(2),
getitimer(2),
nanosleep(2),
select(2),
setitimer(2),
sleep(3),
ualarm(3),
useconds_t(3type),
time(7)
Index
- NAME
-
- LIBRARY
-
- SYNOPSIS
-
- DESCRIPTION
-
- RETURN VALUE
-
- ERRORS
-
- ATTRIBUTES
-
- STANDARDS
-
- HISTORY
-
- CAVEATS
-
- SEE ALSO
-
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