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SIGPROCMASK(2) Linux Programmer's Manual SIGPROCMASK(2)
sigprocmask - examine and change blocked signals
#include <signal.h>
int sigprocmask(int how, const sigset_t *set, sigset_t *oldset);
Feature Test Macro Requirements for glibc (see feature_test_macros(7)):
sigprocmask(): _POSIX_C_SOURCE >= 1 || _XOPEN_SOURCE || _POSIX_SOURCE
sigprocmask() is used to fetch and/or change the signal mask of the calling
thread. The signal mask is the set of signals whose delivery is currently
blocked for the caller (see also signal(7) for more details).
The behavior of the call is dependent on the value of how, as follows.
SIG_BLOCK
The set of blocked signals is the union of the current set and the set
argument.
SIG_UNBLOCK
The signals in set are removed from the current set of blocked signals.
It is permissible to attempt to unblock a signal which is not blocked.
SIG_SETMASK
The set of blocked signals is set to the argument set.
If oldset is non-NULL, the previous value of the signal mask is stored in
oldset.
If set is NULL, then the signal mask is unchanged (i.e., how is ignored), but
the current value of the signal mask is nevertheless returned in oldset (if it
is not NULL).
The use of sigprocmask() is unspecified in a multithreaded process; see
pthread_sigmask(3).
sigprocmask() returns 0 on success and -1 on error.
EINVAL The value specified in how was invalid.
POSIX.1-2001.
It is not possible to block SIGKILL or SIGSTOP. Attempts to do so are
silently ignored.
Each of the threads in a process has its own signal mask.
A child created via fork(2) inherits a copy of its parent's signal mask; the
signal mask is preserved across execve(2).
If SIGBUS, SIGFPE, SIGILL, or SIGSEGV are generated while they are blocked,
the result is undefined, unless the signal was generated by kill(2),
sigqueue(2), or raise(3).
See sigsetops(3) for details on manipulating signal sets.
kill(2), pause(2), sigaction(2), signal(2), sigpending(2), sigqueue(2),
sigsuspend(2), pthread_sigmask(3), sigsetops(3), signal(7)
This page is part of release 3.32 of the Linux man-pages project. A
description of the project, and information about reporting bugs, can be found
at http://www.kernel.org/doc/man-pages/.
Linux 2008-10-17 SIGPROCMASK(2)
HTML rendering created 2010-12-03 by Michael Kerrisk, author of The Linux Programming Interface