SIGADDSET(3) | Library Functions Manual | SIGADDSET(3)

# NAME

`sigemptyset`, `sigfillset`, `sigaddset`, `sigdelset`, `sigismember` — manipulate signal sets

# SYNOPSIS

`#include <signal.h>`

int
`sigemptyset`(sigset_t *set);

int
`sigfillset`(sigset_t *set);

int
`sigaddset`(sigset_t *set, int signo);

int
`sigdelset`(sigset_t *set, int signo);

int
`sigismember`(const sigset_t *set, int signo);

# DESCRIPTION

These functions manipulate signal sets stored in a sigset_t. Either `sigemptyset`() or `sigfillset`() must be called for every object of type sigset_t before any other use of the object. `sigemptyset`() and `sigfillset`() are provided as macros, but actual functions are available if their names are undefined (with #undef name).

The `sigemptyset`() function initializes a signal set to be empty.

`sigfillset`() initializes a signal set to contain all signals.

`sigaddset`() adds the specified signal signo to the signal set.

`sigdelset`() deletes the specified signal signo from the signal set.

`sigismember`() returns whether a specified signal signo is contained in the signal set.

# RETURN VALUES

The `sigismember`() function returns 1 if the signal is a member of the set and 0 otherwise. The other functions return 0 upon success. A -1 return value indicates an error occurred and the global variable errno is set to indicate the reason.

# ERRORS

These functions may fail if one of the following occurs:

[`EINVAL`]
  The specified signal signo is not a valid signal number.

# SEE ALSO

kill(2), sigaction(2), sigpending(2), sigprocmask(2), sigsuspend(2)

# STANDARDS

These functions are defined by IEEE Std 1003.1-1990 (“POSIX.1”).

May 29, 2017 | Debian