usleep(3)

Usage

#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

Library

Standard C library (libc, -lc)

Overview

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	MT-Safe

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.

Releases

19 releases since Debian 1.1 (Buzz); the text changed 14 times.

Referred to by