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usleep(S)


usleep -- suspend execution for an interval

Syntax

cc . . . -lc
#include <unistd.h>

int usleep(useconds_t useconds);

Description

The usleep function suspends the current process from execution for the number of microseconds specified by the useconds argument. Because of other activity, or because of the time spent processing the call, the process may be suspended for longer than specified in useconds.

useconds must be less than one million; if the value is 0, the call has no effect.

usleep uses the process' realtime interval timer to indicate to the system when the process should be awakened. There is one realtime interval timer per process. Previous settings of the timer are not affected by calls to usleep. If the process has the timer prior to calling usleep, and if the value specified in useconds equals or exceeds the timer's prior setting, the process is awakened just before the timer was set to expire.

Note that it is recommended that the setitimer(S) function be used instead of usleep: usleep is supplied for historical reasons.

Return values

Upon successful completion, usleep returns 0. Otherwise, -1 is returned and errno is set to indicate the error.

Diagnostics

If the following error condition occurs, usleep returns -1 and sets errno to the corresponding value:

[EINVAL]
The useconds argument was set to a value equal to or greater than one million.

See also

alarm(S), getitimer(S), sigaction(S), sleep(S)

Standards conformance

usleep is conformant with:

X/Open Portability Guide Issue 4, Version 2 (Spec-1170).


© 2003 Caldera International, Inc. All rights reserved.
SCO OpenServer Release 5.0.7 -- 11 February 2003