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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | NOTES | BUGS | SEE ALSO | COLOPHON |
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sigset(3) Library Functions Manual sigset(3)
sigset, sighold, sigrelse, sigignore - System V signal API
Standard C library (libc, -lc)
#include <signal.h>
typedef void (*sighandler_t)(int);
[[deprecated]] sighandler_t sigset(int sig, sighandler_t disp);
[[deprecated]] int sighold(int sig);
[[deprecated]] int sigrelse(int sig);
[[deprecated]] int sigignore(int sig);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
sigset(), sighold(), sigrelse(), sigignore():
_XOPEN_SOURCE >= 500
These functions are provided in glibc as a compatibility
interface for programs that make use of the historical System V
signal API. This API is obsolete: new applications should use
the POSIX signal API (sigaction(2), sigprocmask(2), etc.)
The sigset() function modifies the disposition of the signal sig.
The disp argument can be the address of a signal handler
function, or one of the following constants:
SIG_DFL
Reset the disposition of sig to the default.
SIG_IGN
Ignore sig.
SIG_HOLD
Add sig to the process's signal mask, but leave the
disposition of sig unchanged.
If disp specifies the address of a signal handler, then sig is
added to the process's signal mask during execution of the
handler.
If disp was specified as a value other than SIG_HOLD, then sig is
removed from the process's signal mask.
The dispositions for SIGKILL and SIGSTOP cannot be changed.
The sighold() function adds sig to the calling process's signal
mask.
The sigrelse() function removes sig from the calling process's
signal mask.
The sigignore() function sets the disposition of sig to SIG_IGN.
On success, sigset() returns SIG_HOLD if sig was blocked before
the call, or the signal's previous disposition if it was not
blocked before the call. On error, sigset() returns -1, with
errno set to indicate the error. (But see BUGS below.)
The sighold(), sigrelse(), and sigignore() functions return 0 on
success; on error, these functions return -1 and set errno to
indicate the error.
For sigset() see the ERRORS under sigaction(2) and
sigprocmask(2).
For sighold() and sigrelse() see the ERRORS under sigprocmask(2).
For sigignore(), see the errors under sigaction(2).
For an explanation of the terms used in this section, see
attributes(7).
┌─────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├─────────────────────────────────────┼───────────────┼─────────┤
│ sigset(), sighold(), sigrelse(), │ Thread safety │ MT-Safe │
│ sigignore() │ │ │
└─────────────────────────────────────┴───────────────┴─────────┘
POSIX.1-2008.
sighandler_t
GNU. POSIX.1 uses the same type but without a typedef.
glibc 2.1. SVr4, POSIX.1-2001. POSIX.1-2008 marks these
functions as obsolete, recommending the use of sigaction(2),
sigprocmask(2), pthread_sigmask(3), and sigsuspend(2) instead.
The sigset() function provides reliable signal handling semantics
(as when calling sigaction(2) with sa_mask equal to 0).
On System V, the signal() function provides unreliable semantics
(as when calling sigaction(2) with sa_mask equal to SA_RESETHAND
| SA_NODEFER). On BSD, signal() provides reliable semantics.
POSIX.1-2001 leaves these aspects of signal() unspecified. See
signal(2) for further details.
In order to wait for a signal, BSD and System V both provided a
function named sigpause(3), but this function has a different
argument on the two systems. See sigpause(3) for details.
Before glibc 2.2, sigset() did not unblock sig if disp was
specified as a value other than SIG_HOLD.
Before glibc 2.5, sigset() does not correctly return the previous
disposition of the signal in two cases. First, if disp is
specified as SIG_HOLD, then a successful sigset() always returns
SIG_HOLD. Instead, it should return the previous disposition of
the signal (unless the signal was blocked, in which case SIG_HOLD
should be returned). Second, if the signal is currently blocked,
then the return value of a successful sigset() should be
SIG_HOLD. Instead, the previous disposition of the signal is
returned. These problems have been fixed since glibc 2.5.
kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2),
raise(3), sigpause(3), sigvec(3), signal(7)
This page is part of the man-pages (Linux kernel and C library
user-space interface documentation) project. Information about
the project can be found at
⟨https://www.kernel.org/doc/man-pages/⟩. If you have a bug report
for this manual page, see
⟨https://git.kernel.org/pub/scm/docs/man-pages/man-pages.git/tree/CONTRIBUTING⟩.
This page was obtained from the tarball man-pages-6.9.1.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2024-06-26. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-
to-date source for the page, or you have corrections or
improvements to the information in this COLOPHON (which is not
part of the original manual page), send a mail to
man-pages@man7.org
Linux man-pages 6.9.1 2024-05-02 sigset(3)
Pages that refer to this page: sigvec(3), signal(7), signal-safety(7)
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HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
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