NAME
sigprocmask —
manipulate current signal
mask
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 from
⟨signal.h⟩:
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 indicated that the call succeeded. A -1 return value indicates an error occurred and errno is set to indicated 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
STANDARDS
The sigprocmask() function call is
expected to conform to IEEE Std 1003.1-1988
(“POSIX.1”).