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NAME | LIBRARY | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | ATTRIBUTES | STANDARDS | HISTORY | NOTES | SEE ALSO | COLOPHON |
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sigvec(3) Library Functions Manual sigvec(3)
sigvec, sigblock, sigsetmask, siggetmask, sigmask - BSD signal API
Standard C library (libc, -lc)
#include <signal.h>
[[deprecated]] int sigvec(int sig, const struct sigvec *vec,
struct sigvec *ovec);
[[deprecated]] int sigmask(int signum);
[[deprecated]] int sigblock(int mask);
[[deprecated]] int sigsetmask(int mask);
[[deprecated]] int siggetmask(void);
Feature Test Macro Requirements for glibc (see
feature_test_macros(7)):
All functions shown above:
Since glibc 2.19:
_DEFAULT_SOURCE
glibc 2.19 and earlier:
_BSD_SOURCE
These functions are provided in glibc as a compatibility interface
for programs that make use of the historical BSD signal API. This
API is obsolete: new applications should use the POSIX signal API
(sigaction(2), sigprocmask(2), etc.).
The sigvec() function sets and/or gets the disposition of the
signal sig (like the POSIX sigaction(2)). If vec is not NULL, it
points to a sigvec structure that defines the new disposition for
sig. If ovec is not NULL, it points to a sigvec structure that is
used to return the previous disposition of sig. To obtain the
current disposition of sig without changing it, specify NULL for
vec, and a non-null pointer for ovec.
The dispositions for SIGKILL and SIGSTOP cannot be changed.
The sigvec structure has the following form:
struct sigvec {
void (*sv_handler)(int); /* Signal disposition */
int sv_mask; /* Signals to be blocked in handler */
int sv_flags; /* Flags */
};
The sv_handler field specifies the disposition of the signal, and
is either: the address of a signal handler function; SIG_DFL,
meaning the default disposition applies for the signal; or
SIG_IGN, meaning that the signal is ignored.
If sv_handler specifies the address of a signal handler, then
sv_mask specifies a mask of signals that are to be blocked while
the handler is executing. In addition, the signal for which the
handler is invoked is also blocked. Attempts to block SIGKILL or
SIGSTOP are silently ignored.
If sv_handler specifies the address of a signal handler, then the
sv_flags field specifies flags controlling what happens when the
handler is called. This field may contain zero or more of the
following flags:
SV_INTERRUPT
If the signal handler interrupts a blocking system call,
then upon return from the handler the system call is not
restarted: instead it fails with the error EINTR. If this
flag is not specified, then system calls are restarted by
default.
SV_RESETHAND
Reset the disposition of the signal to the default before
calling the signal handler. If this flag is not specified,
then the handler remains established until explicitly
removed by a later call to sigvec() or until the process
performs an execve(2).
SV_ONSTACK
Handle the signal on the alternate signal stack
(historically established under BSD using the obsolete
sigstack() function; the POSIX replacement is
sigaltstack(2)).
The sigmask() macro constructs and returns a "signal mask" for
signum. For example, we can initialize the vec.sv_mask field
given to sigvec() using code such as the following:
vec.sv_mask = sigmask(SIGQUIT) | sigmask(SIGABRT);
/* Block SIGQUIT and SIGABRT during
handler execution */
The sigblock() function adds the signals in mask to the process's
signal mask (like POSIX sigprocmask(SIG_BLOCK)), and returns the
process's previous signal mask. Attempts to block SIGKILL or
SIGSTOP are silently ignored.
The sigsetmask() function sets the process's signal mask to the
value given in mask (like POSIX sigprocmask(SIG_SETMASK)), and
returns the process's previous signal mask.
The siggetmask() function returns the process's current signal
mask. This call is equivalent to sigblock(0).
The sigvec() function returns 0 on success; on error, it returns
-1 and sets errno to indicate the error.
The sigblock() and sigsetmask() functions return the previous
signal mask.
The sigmask() macro returns the signal mask for signum.
See the ERRORS under sigaction(2) and sigprocmask(2).
For an explanation of the terms used in this section, see
attributes(7).
┌──────────────────────────────────────┬───────────────┬─────────┐
│ Interface │ Attribute │ Value │
├──────────────────────────────────────┼───────────────┼─────────┤
│ sigvec(), sigmask(), sigblock(), │ Thread safety │ MT-Safe │
│ sigsetmask(), siggetmask() │ │ │
└──────────────────────────────────────┴───────────────┴─────────┘
None.
sigvec()
sigblock()
sigmask()
sigsetmask()
4.3BSD.
siggetmask()
Unclear origin.
sigvec()
Removed in glibc 2.21.
On 4.3BSD, the signal() function provided reliable semantics (as
when calling sigvec() with vec.sv_mask equal to 0). On System V,
signal() provides unreliable semantics. POSIX.1 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.
kill(2), pause(2), sigaction(2), signal(2), sigprocmask(2),
raise(3), sigpause(3), sigset(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-6.15.tar.gz
fetched from
⟨https://mirrors.edge.kernel.org/pub/linux/docs/man-pages/⟩ on
2025-08-11. 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 6.15 2025-05-17 sigvec(3)
Pages that refer to this page: sgetmask(2), sigaction(2), signal(2), sigpause(3), sigset(3), signal(7)
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HTML rendering created 2025-09-06 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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