June 4, 1993 SIGSETOPS 3

### NAME

sigemptyset, sigfillset, sigaddset, sigdelset, sigismember - manipulate signal sets

### LIBRARY

Standard C Library (libc, -lc)

### SYNOPSIS

```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(```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.

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

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

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

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

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

sigemptyset(``) and sigfillset(``) are provided as macros, but actual functions are available if their names are undefined (with #undef name).

### RETURN VALUES

The 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 errno is set to indicate the reason.

### ERRORS

These functions could fail if one of the following occurs:

[```EINVAL`]
  ```signo` has an invalid value.

### SEE ALSO

kill(2), sigaction(2), sigsuspend(2), signal(7)

### STANDARDS

These functions conform to ISO/IEC 9945-1:1990 (``POSIX.1'') .