.\" Copyright (c) 1980 Regents of the University of California.
.\" All rights reserved. The Berkeley software License Agreement
.\" specifies the terms and conditions for redistribution.
.\" @(#)sigset.3 4.1 (Berkeley) 5/15/85
sigset, signal, sighold, sigignore, sigrelse, sigpause \- manage signals
This is a package of signal management functions to manage the signals
These functions are available only in this version of UNIX, and should
not be used when the mechanisms of
would suffice, as they would then impair portability.
These functions are contained in the \fIjobs\fR library, obtained by
specifying the loader option \fB\-ljobs\fR.
is used to provide a default signal handler for signal
This function is remembered across subsequent calls to the other
functions, and need not be specified again.
will cause an interrupt to be taken at
with the signal then held so that recursive trapping due to
the signal will not occur. During normal return from
the routines arrange for the signal action to be restored so that
subsequent signals will also trap to
If a non-local exit is to be taken, then
must be called to un-hold the signal action, restoring the
SIG_DFL, SIG_IGN or SIG_HOLD, as described in
The value specified on the previous call to
has never been called, then the default action inherited from the
but the signal will not be held when the action routine is called;
rather it will have reverted to SIG_DFL.
This is generally unsafe, but is included for backwards compatibility
to the old signal mechanism.
in a piece of code where it cannot be tolerated.
the catch initially set with
can be used to temporarily set the action for
to ignore the signal. If the signal had been held before
any pending instance of the signal will be discarded.
may be used by a routine which wishes to check for some condition
produced at interrupt level by the
signal, and then to pause waiting for the condition to arise with
the catch of the signal enabled.
In correct usage it must be preceded by an instance of
in that it will return after
The usual thing to do then is to reenable the hold with
again if the condition has not arisen.
sigsys(2), signal(2), jobs(3), tty(4)
restores the default catch.
These functions store information in data space. You thus
in the child which is to then