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.Dd June 4, 1993
.Dt SIGSETOPS 3
.Os
.Sh NAME
.Nm sigemptyset ,
.Nm sigfillset ,
.Nm sigaddset ,
.Nm sigdelset ,
.Nm sigismember
.Nd manipulate signal sets
.Sh SYNOPSIS
.Fd #include <signal.h>
.Ft int
.Fn sigemptyset "sigset_t *set"
.Ft int
.Fn sigfillset "sigset_t *set"
.Ft int
.Fn sigaddset "sigset_t *set" "int signo"
.Ft int
.Fn sigdelset "sigset_t *set" "int signo"
.Ft int
.Fn sigismember "const sigset_t *set" "int signo"
.Sh DESCRIPTION
These functions manipulate signal sets stored in a
.Fa sigset_t .
Either
.Fn sigemptyset
or
.Fn sigfillset
must be called for every object of type
.Fa sigset_t
before any other use of the object.
.Fn sigemptyset
and
.Fn sigfillset
are provided as macros, but actual functions are available
if their names are undefined (with #undef
.Ar name ) .
.Pp
The
.Fn sigemptyset
function initializes a signal set to be empty.
.Pp
.Fn sigfillset
initializes a signal set to contain all signals.
.Pp
.Fn sigaddset
adds the specified signal
.Fa signo
to the signal set.
.Pp
.Fn sigdelset
deletes the specified signal
.Fa signo
from the signal set.
.Pp
.Fn sigismember
returns whether a specified signal
.Fa signo
is contained in the signal set.
.Sh RETURN VALUES
The
.Fn sigismember
function returns 1
if the signal is a member of the set,
a 0 otherwise.
The other functions return 0 upon success.
A \-1 return value
indicates an error occurred and the global variable
.Va errno
is set to indicate the reason.
.Sh ERRORS
These functions may fail if one of the following occurs:
.Bl -tag -width Er
.It Bq Er EINVAL
The specified signal
.Fa signo
is not a valid signal number.
.El
.Sh SEE ALSO
.Xr kill 2 ,
.Xr sigaction 2 ,
.Xr sigpending 2 ,
.Xr sigprocmask 2 ,
.Xr sigsuspend 2
.Sh STANDARDS
These functions are defined by
.St -p1003.1-90 .