Section: Linux Programmer's Manual (3)
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ualarm - schedule signal after given number of microseconds
useconds_t ualarm(useconds_t usecs, useconds_t interval);
Feature Test Macro Requirements for glibc (see
- Since glibc 2.12:
(_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
function causes the signal
to be sent to the invoking process after (not less than)
The delay may be lengthened slightly by any system activity
or by the time spent processing the call or by the
granularity of system timers.
Unless caught or ignored, the
signal will terminate the process.
argument is nonzero, further
signals will be sent every
microseconds after the first.
This function returns the number of microseconds remaining for
any alarm that was previously set, or 0 if no alarm was pending.
Interrupted by a signal.
usecs or interval is not smaller than 1000000.
(On systems where that is considered an error.)
POSIX.1-2008 removes the specification of
4.3BSD, SUSv2, and POSIX do not define any errors.
POSIX.1-2001 does not specify what happens if the
argument is 0.
On Linux (and probably most other systems),
the effect is to cancel any pending alarm.
is an unsigned integer type capable of holding integers
in the range [0,1000000].
On the original BSD implementation, and in glibc before version 2.1,
the arguments to
were instead typed as
Programs will be more portable if they never mention
The interaction of this function with
other timer functions such as
This function is obsolete.
or POSIX interval timers
This page is part of release 3.54 of the Linux
A description of the project,
and information about reporting bugs,
can be found at
- RETURN VALUE
- CONFORMING TO
- SEE ALSO
This document was created by
using the manual pages.
Time: 07:38:53 GMT, January 16, 2018