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sigprocmask(2) [freebsd man page]

SIGPROCMASK(2)						      BSD System Calls Manual						    SIGPROCMASK(2)

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() 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 ISO/IEC 9945-1:1990 (``POSIX.1''). BSD
May 7, 2010 BSD

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SIGPROCMASK(2)						     Linux Programmer's Manual						    SIGPROCMASK(2)

NAME
sigprocmask - examine and change blocked signals SYNOPSIS
#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 DESCRIPTION
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). RETURN VALUE
sigprocmask() returns 0 on success and -1 on error. ERRORS
EINVAL The value specified in how was invalid. CONFORMING TO
POSIX.1-2001. NOTES
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. SEE ALSO
kill(2), pause(2), sigaction(2), signal(2), sigpending(2), sigqueue(2), sigsuspend(2), pthread_sigmask(3), sigsetops(3), signal(7) COLOPHON
This page is part of release 3.25 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)

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