sigpending(2) — Linux manual page


sigpending(2)              System Calls Manual             sigpending(2)

NAME         top

       sigpending, rt_sigpending - examine pending signals

LIBRARY         top

       Standard C library (libc, -lc)

SYNOPSIS         top

       #include <signal.h>

       int sigpending(sigset_t *set);

   Feature Test Macro Requirements for glibc (see


DESCRIPTION         top

       sigpending() returns the set of signals that are pending for
       delivery to the calling thread (i.e., the signals which have been
       raised while blocked).  The mask of pending signals is returned
       in set.

RETURN VALUE         top

       sigpending() returns 0 on success.  On failure, -1 is returned
       and errno is set to indicate the error.

ERRORS         top

       EFAULT set points to memory which is not a valid part of the
              process address space.

STANDARDS         top


HISTORY         top


   C library/kernel differences
       The original Linux system call was named sigpending().  However,
       with the addition of real-time signals in Linux 2.2, the fixed-
       size, 32-bit sigset_t argument supported by that system call was
       no longer fit for purpose.  Consequently, a new system call,
       rt_sigpending(), was added to support an enlarged sigset_t type.
       The new system call takes a second argument, size_t sigsetsize,
       which specifies the size in bytes of the signal set in set.  The
       glibc sigpending() wrapper function hides these details from us,
       transparently calling rt_sigpending() when the kernel provides

NOTES         top

       See sigsetops(3) for details on manipulating signal sets.

       If a signal is both blocked and has a disposition of "ignored",
       it is not added to the mask of pending signals when generated.

       The set of signals that is pending for a thread is the union of
       the set of signals that is pending for that thread and the set of
       signals that is pending for the process as a whole; see

       A child created via fork(2) initially has an empty pending signal
       set; the pending signal set is preserved across an execve(2).

BUGS         top

       Up to and including glibc 2.2.1, there is a bug in the wrapper
       function for sigpending() which means that information about
       pending real-time signals is not correctly returned.

SEE ALSO         top

       kill(2), sigaction(2), signal(2), sigprocmask(2), sigsuspend(2),
       sigsetops(3), signal(7)

COLOPHON         top

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Linux man-pages 6.9.1          2024-05-02                  sigpending(2)

Pages that refer to this page: clone(2)fork(2)sigaction(2)signal(2)sigprocmask(2)sigwaitinfo(2)syscalls(2)pthread_create(3)pthread_kill(3)pthread_sigmask(3)sigsetops(3)sigwait(3)signal(7)signal-safety(7)system_data_types(7)