sigemptyset(3)sigemptyset(3)NAME
sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - Create and
manipulates signal masks
SYNOPSIS
#include <signal.h>
int sigemptyset(
sigset_t *set ); int sigfillset(
sigset_t *set ); int sigaddset(
sigset_t *set,
int sig_number ); int sigdelset(
sigset_t *set,
int sig_number ); int sigismember(
sigset_t *set,
int sig_number );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry stan‐
dards as follows:
sigemptyset(), sigfillset(), sigaddset(), sigdelset() sigismem‐
ber(): XPG4, XPG4-UNIX
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
Specifies the signal set. Specifies the individual signal.
DESCRIPTION
The sigemptyset(),sigfillset(),sigaddset()sigdelset() and sigismember()
functions manipulate sets of signals. These functions operate on data
objects that can be addressed by the application, not on any set of
signals known to the system, such as the set blocked from delivery to a
process or the set pending for a process.
The sigemptyset() function initializes the signal set pointed to by the
set parameter such that all signals are excluded. The sigfillset()
function initializes the signal set pointed to by the set parameter
such that all signals are included. A call to either the sigfillset()
or sigemptyset() function must be made at least once for each object of
the type sigset_t prior to any other use of that object.
The sigaddset() and sigdelset() functions respectively add and delete
the individual signal specified by the sig_number parameter from the
signal set specified by the set parameter. The sigismember() function
tests whether the sig_number parameter is a member of the signal set
pointed to by the set parameter.
RETURN VALUES
Upon successful completion, the sigismember() function returns a value
of 1 if the specified signal is a member of the specified set, or a
value of 0 (zero) if it is not. Upon successful completion, the other
functions return a value of 0. For all the preceding functions, if an
error is detected, a value of -1 is returned and errno is set to indi‐
cate the error.
ERRORS
The sigfillset(), sigdelset(), sigismember(), and sigaddset() functions
set errno to the specified values for the following conditions: The
value of the sig_number parameter is not a valid signal number.
EXAMPLES
To generate and use a signal mask that blocks only the SIGINT signal
from delivery, enter:
#include <signal.h> int return_value; sigset_t newset;
. . . sigemptyset(&newset); sigaddset(&newset, SIGINT);
return_value = sigprocmask (SIG_SETMASK, &newset, NULL);
SEE ALSO
Functions: sigaction(2), sigprocmask(2), sigsuspend(2), sigvec(2)
Files: signal(4)
Standards: standards(5)sigemptyset(3)
