usleep — suspend execution for microsecond intervals
#include <unistd.h>
int
usleep( |
useconds_t | usec) ; |
Note | |||
---|---|---|---|
|
The 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.
Interrupted by a signal.
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.
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.
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.
alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), ualarm(3), sleep(3), time(7)
This page is part of release 2.79 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/.
Copyright 1993 David Metcalfe (davidprism.demon.co.uk) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. References consulted: Linux libc source code Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991) 386BSD man pages Modified 1993-07-24 by Rik Faith (faithcs.unc.edu) Modified 2001-04-01 by aeb Modified 2003-07-23 by aeb |