alarm(2) System Calls alarm(2)
alarm - schedule an alarm signal
unsigned int alarm(unsigned int sec);
The alarm() function causes the system to generate a SIGALRM signal for
the process after the number of real-time seconds specified by seconds
have elapsed (see signal.h(3HEAD)). Processor scheduling delays may
prevent the process from handling the signal as soon as it is gener-
If seconds is 0, a pending alarm request, if any, is cancelled.
Alarm requests are not stacked; only one SIGALRM generation can be
scheduled in this manner; if the SIGALRM signal has not yet been gener-
ated, the call will result in rescheduling the time at which the
SIGALRM signal will be generated.
The fork(2) function clears pending alarms in the child process. A new
process image created by one of the exec functions inherits the time
left to an alarm signal in the old process's image.
If there is a previous alarm request with time remaining, alarm()
returns a non-zero value that is the number of seconds until the
previous request would have generated a SIGALRM signal. Otherwise,
alarm() returns 0.
The alarm() function is always successful; no return value is reserved
to indicate an error.
See attributes(5) for descriptions of the following attributes:
tab() allbox; cw(2.750000i)| cw(2.750000i) lw(2.750000i)|
lw(2.750000i). ATTRIBUTE TYPEATTRIBUTE VALUE Interface StabilityStan-
exec(2), fork(2), signal.h(3HEAD), attributes(5), standards(5)
SunOS 5.10 7 Jun 2001 alarm(2)