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alarm(2)                         System Calls                         alarm(2)



NAME
       alarm - schedule an alarm signal

SYNOPSIS
       #include <unistd.h>

       unsigned int alarm(unsigned int sec);

DESCRIPTION
       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-
       ated.

       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.

RETURN VALUES
       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.

ERRORS
       The  alarm() function is always successful; no return value is reserved
       to indicate an error.

ATTRIBUTES
       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-
       dard MT-LevelAsync-Signal-Safe


SEE ALSO
       exec(2), fork(2), signal.h(3HEAD), attributes(5), standards(5)



SunOS 5.10                        7 Jun 2001                          alarm(2)