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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 "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
.Em name ) .
.Pp
The
.Fn sigemptyset
function initializes a signal set to be empty.
.Pp
The
.Fn sigfillset
function initializes a signal set to contain all signals.
.Pp
The
.Fn sigaddset
function adds the specified signal
.Fa signo
to the signal set.
.Pp
The
.Fn sigdelset
function deletes the specified signal
.Fa signo
from the signal set.
.Pp
The
.Fn sigismember
function returns whether a specified signal
.Fa signo
is contained in the signal set.
.Pp
These functions
are provided as macros in the include file <signal.h>.
Actual functions are available
if their names are undefined (with #undef
.Em name ) .
.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 indicated the reason.
.Sh ERRORS
These functions could fail if one of the following occurs:
.Bl -tag -width Er
.It Bq Er EINVAL
.Fa signo
has an invalid value.
.El
.Sh SEE ALSO
.Xr kill 2 ,
.Xr sigaction 2 ,
.Xr sigsuspend 2
.Sh STANDARDS
These functions are defined by
.St -p1003.1-90 .