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usleep(3) — Linux manual page

usleep(3) Library Functions Manual usleep(3)

NAME top

 usleep - suspend execution for microsecond intervals

LIBRARY top

 Standard C library (libc, -lc)

SYNOPSIS top

 #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 top

 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 top

 The usleep() function returns 0 on success. On error, -1 is
 returned, with errno  set to indicate the error.

ERRORS top

 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 top

 For an explanation of the terms used in this section, see
 attributes(7).
 ┌──────────────────────────────────────┬───────────────┬─────────┐
 │ Interface │ Attribute │ Value │
 ├──────────────────────────────────────┼───────────────┼─────────┤
 │ usleep() │ Thread safety │ MT-Safe │
 └──────────────────────────────────────┴───────────────┴─────────┘

STANDARDS top

 None.

HISTORY top

 4.3BSD, POSIX.1-2001. POSIX.1-2001 declares it obsolete,
 suggesting nanosleep(2) instead. Removed in POSIX.1-2008.
 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.1-2001.

CAVEATS top

 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 top

 alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2),
 sleep(3), ualarm(3), useconds_t(3type), time(7)

COLOPHON top

 This page is part of the man-pages (Linux kernel and C library
 user-space interface documentation) project. Information about
 the project can be found at 
 ⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
 for this manual page, see
 ⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
 This page was obtained from the tarball man-pages-6.10.tar.gz
 fetched from
 ⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
 2025年02月02日. If you discover any rendering problems in this HTML
 version of the page, or you believe there is a better or more up-
 to-date source for the page, or you have corrections or
 improvements to the information in this COLOPHON (which is not
 part of the original manual page), send a mail to
 man-pages@man7.org
Linux man-pages 6.10 2024年07月23日 usleep(3)

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Pages that refer to this page: free(1), gawk(1), clock_nanosleep(2), getitimer(2), nanosleep(2), select(2), __ppc_get_timebase(3), time_t(3type), ualarm(3), signal(7), time(7)

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