HP 3000 Manuals

MPE/iX Developer's Kit Reference Manual Volume I

alarm 

Schedules a SIGALRM signal.

Syntax 

     #include <unistd.h>
     unsigned int alarm (unsigned int seconds);

Parameters 

seconds    The number of real-time seconds to wait before generating a
           SIGALRM signal.  A zero cancels any previously scheduled alarm
           request.

Return Values 

0          Success.  There is no previously scheduled alarm.

>0         Success.  The number of seconds remaining on a previously
           scheduled alarm is returned.

Description 

The alarm() function causes the operating system to generate a SIGALRM
signal for the calling process after the number of real-time seconds
specified by the seconds parameter have elapsed.  Operating system
scheduling delays may prevent delivery of the signal until after the
specified time.

Only one SIGALRM signal can be scheduled at a time.  Any previously
scheduled alarm is cancelled by the current alarm.  A previously
scheduled alarm is cancelled by passing zero in the seconds parameter.

Implementation Considerations 

Currently, alarm() does not cause a read timeout.

Errors 

None.

See Also 

fork(), pause(), sigaction(), <signal.h>, POSIX.1 (Section 3.4.1)

MPE/iX 5.0 Documentation