setpause(2) argument

[Myers]

In article <8540 at ncar.ucar.edu> steve at groucho.ucar.edu (Steve Emmerson) writes:
>Would someone who *knows* please tell me the type of argument expected
>by the sigpause(2) system call.  Is it a signal-number or a signal-mask?
>
>Steve Emmerson        steve at unidata.ucar.edu        ...!ncar!unidata!steve

The following is copied directly from the UNICOS System Calls course
taught here last week by CRAY; the reference manual UNICOS System Calls
and C library Routines (TR-USC), page 10-66.  Like I said, we just had
the class last week and I've not used this at all nor do I claim to
*know*.  BTW, we're currently migrating to UNICOS.  Hope this helps.

Cindy Myers
rebein at dtrc.dt.navy.mil
(301) 227-1271

NAME
    sigpause - suspend a process until signal received

SYNOPSIS
    int sigpause (sig)
    int sig;

RETURN
    0 -> successful
    1 -> failure

Like pause, the sigpause system call will suspend a process until ANY
signal is received.  Unlike pause, sigpause requires an argument sig.
The argument sig indicates that if a signal of that type has been
received by the process and is being held, it will be released and the
appropriate signal action taken.

NOTE:  sigpause DOES NOT cause process suspension waiting for only one
signal type (sig) but will be suspended until ANY signal type is
received.

According to the SR-2012 manual, sigpause has a special application.
It states that sigpause is useful for testing variables that are
changed on the occurrence of a signal.  The correct usage is to use
sighold to block a signal first, then test the variables.  If they have
not changed, call the sigpause system call to wait for the signal.