NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO | COLOPHON
UALARM(3) Linux Programmer's Manual UALARM(3)
ualarm - schedule signal after given number of microseconds
#include <unistd.h>
useconds_t ualarm(useconds_t usecs, useconds_t interval);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
ualarm(): _BSD_SOURCE || _XOPEN_SOURCE >= 500
The ualarm() function causes the signal SIGALRM to be sent to the invoking
process after (not less than) usecs microseconds. 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 SIGALRM signal will terminate the process.
If the interval argument is non-zero, further SIGALRM signals will be sent
every interval 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.
EINTR Interrupted by a signal.
EINVAL usecs or interval is not smaller than 1000000. (On systems where that
is considered an error.)
4.3BSD, POSIX.1-2001. POSIX.1-2001 marks ualarm() as obsolete. POSIX.1-2008
removes the specification of ualarm(). 4.3BSD, SUSv2, and POSIX do not define
any errors.
The type useconds_t 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 ualarm() were instead typed as unsigned
int. Programs will be more portable if they never mention useconds_t
explicitly.
The interaction of this function 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), usleep(3) is
unspecified.
This function is obsolete. Use setitimer(2) or POSIX interval timers
(timer_create(2), etc.) instead.
alarm(2), getitimer(2), nanosleep(2), select(2), setitimer(2), usleep(3),
time(7)
This page is part of release 3.23 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/.
2008-08-06 UALARM(3)