April 19, 1994 ALARM 3

### NAME

alarm - set signal timer alarm

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```unsigned` `int` alarm(```unsigned int seconds`)

### DESCRIPTION

This interface is made obsolete by setitimer(2).

The alarm(``) function sets a timer to deliver the signal ```SIGALRM` to the calling process seconds after the call to alarm(``). If an alarm has already been set with alarm(``) but has not been delivered, another call to alarm(``) will supersede the prior call. The request alarm(```0`) voids the current alarm and the signal SIGALRM will not be delivered. The maximum number of seconds allowed is 2147483647.

The return value of alarm(``) is the amount of time left on the timer from a previous call to alarm(``). If no alarm is currently set, the return value is 0. If there is an error setting the timer, alarm(``) returns ((unsigned int) -1).

### SEE ALSO

setitimer(2), sigaction(2), sigsuspend(2), signal(3), sigvec(3), sleep(3), ualarm(3), usleep(3)

### STANDARDS

The alarm(``) function conforms to ISO/IEC 9945-1:1990 (``POSIX.1'') .

### HISTORY

An alarm(``) function appeared in Version 7 `AT&T UNIX`.