alarm —
set signal timer alarm
#include
<unistd.h>
unsigned int
alarm(
unsigned
int seconds);
The
alarm() function waits a count of
seconds before asserting the terminating
signal
SIGALRM. When the signal has
successfully been caught,
alarm() returns
the amount of time left on the clock. The maximum number of
seconds allowed is 100000000.
If an alarm has been set with
alarm(),
another call to
alarm() will supersede the
prior call. The request
alarm(
0)
voids the current alarm.
If the call succeeds, any time left remaining from a previous call is returned.
If an error occurs, the value -1 is returned, and a more precise error code is
placed in the global variable
errno.
setitimer(2),
sigaction(2),
sigsuspend(2),
signal(3),
sleep(3),
ualarm(3)
The
alarm() function conforms to
IEEE Std 1003.1-2008
(“POSIX.1”).
An
alarm() system call appeared in the
Programmer's Workbench (PWB/UNIX) and was ported to
Version 7 AT&T UNIX. For
4.1cBSD, it was reimplemented as a wrapper around the
setitimer(2) system
call.
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