.TH sigaddset() "" "" "Signal Function (libc)"
.PC "Add a signal to a set of signals"
.B "#include <signal.h>"
\fBint sigaddset (\fIset\^\fB, \fIsigno\^\fB)\fR
\fBsigset_t *\fIset\^\fB; int \fIsigno\^\fB;\fR
.PP
.B sigaddset()
is one of a set of signalling functions that manipulate
data objects addressable by the application, instead of a
set of signals known to the system.
It adds the signal
.I signo
to the set of signals to which
.I set
points.
.PP
If all goes well,
.B sigaddset()
returns zero.
If
.I signo
is set to an invalid or unsupported value,
it returns \-1 and sets
.B errno
to
.BR EINVAL .
.SH "See Also"
.Xr "libc," libc
.Xr "sigaction()," sigaction
.Xr "sigdelset()," sigdelset
.Xr "sigemptyset()," sigemptys
.Xr "sigfillset()," sigfillse
.Xr "sigismember()" sigismemb
.SH Notes
If your program is compiled using the System V Release 4 compilation
environment, this is a function that is linked in from
.BR libc .
If not, a macro form is used.
