NAME
sigprocmask —
manipulate current signal
mask
LIBRARY
library “libc”
SYNOPSIS
#include
<signal.h>
int
sigprocmask(int how,
const sigset_t * restrict set,
sigset_t * restrict oset);
DESCRIPTION
Thesigprocmask()
system call 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 how argument. 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.
In threaded applications,
pthread_sigmask(3) must be used instead of
sigprocmask().
RETURN VALUES
The sigprocmask() function returns the
value 0 if successful; otherwise the value -1 is returned and
the global variable errno is set to indicate the
error.
ERRORS
The sigprocmask() system call will fail
and the signal mask will be unchanged if one of the following occurs:
- [
EINVAL] - The how argument has a value other than those listed here.
SEE ALSO
kill(2), sigaction(2), sigpending(2), sigsuspend(2), fpsetmask(3), pthread_sigmask(3), sigsetops(3)
STANDARDS
The sigprocmask() system call is expected
to conform to IEEE Std 1003.1-1990
(“POSIX.1”).