| NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON | The Linux Programming Interface |
USLEEP(3) Linux Programmer's Manual USLEEP(3)
usleep - suspend execution for microsecond intervals
#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
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.
0 on success, -1 on error.
EINTR Interrupted by a signal; see signal(7).
EINVAL usec is not smaller than 1000000. (On systems where that is considered
an error.)
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.
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(2), timer_delete(2), timer_getoverrun(2), timer_gettime(2),
timer_settime(2), ualarm(3) is unspecified.
alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), sleep(3),
ualarm(3), time(7)
This page is part of release 3.32 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/.
2010-12-03 USLEEP(3)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface