

alarm()                COHERENT System Call               alarm()




Set a timer

aallaarrmm(_n)
uunnssiiggnneedd _n;

alarm sets  a timer associated with the  requesting process to go
off in  n seconds.  After n seconds, the  system sends the signal
SIGALRM to the process.  An  argument of zero turns off the alarm
timer.

By  default, the  receipt of  the  SIGALRM signal  terminates the
process.  However,  it may be caught or  ignored by using signal.
Because of  scheduling variation and the  one second granularity,
the action of alarm is predictable only to within one second.

alarm is  useful for such  things as timeouts.   For example, the
login process  on a dial-in port  might hang up the  line after a
sufficient time has elapsed with no user response.

alarm returns the previous alarm value, which represents the time
remaining from  the previous call.  Time  remaining is superseded
by the new alarm value.

***** See Also *****

COHERENT system calls, signal(), sleep()






























COHERENT Lexicon                                           Page 1


