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.
RETURN VALUES
The sigismember function returns 1 if the signal is a member of the set, 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:
