NAME
sigprocmask —
manipulate current signal
mask
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <signal.h>
int
sigprocmask(
int
how,
const sigset_t *
restrict set,
sigset_t *
restrict oset);
DESCRIPTION
The
sigprocmask() function examines and/or changes the current
signal mask (those signals that are blocked from delivery). Signals are
blocked if they are members of the current signal mask set.
If
set is not null, the action of
sigprocmask() depends on the value of the parameter
how. The signal mask is changed as a function of the
specified
set and the current mask. The function is
specified by
how using one of the following values:
-
-
SIG_BLOCK
- The new mask is the union of the current mask and the
specified set.
-
-
SIG_UNBLOCK
- The new mask is the intersection of the current mask and
the complement of the specified set.
-
-
SIG_SETMASK
- The current mask is replaced by the specified
set.
If
oset is not null, it is set to the previous value of
the signal mask.
When
set is null, the value of
how
is insignificant and the mask remains unset providing a way to examine the
signal mask without modification.
The system quietly disallows
SIGKILL
or
SIGSTOP
to be blocked.
RETURN VALUES
A 0 value indicates that the call succeeded. A -1 return value indicates an
error occurred and
errno is set to indicate the reason.
ERRORS
The
sigprocmask() call will fail and the signal mask will be
unchanged if one of the following occurs:
-
-
- [
EINVAL
]
- how has a value other than those
listed here.
SEE ALSO
kill(2),
sigaction(2),
sigsuspend(2),
pthread_sigmask(3),
sigsetops(3),
signal(7)
STANDARDS
The
sigprocmask() function conforms to
IEEE
Std 1003.1-1990 (“POSIX.1”).