.\" Copyright (c) 2005 Michael Kerrisk
.\" based on earlier work by faith@cs.unc.edu and
.\" Mike Battersby <mib@deakin.edu.au>
.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
.\" manual page may be incorrect or out-of-date.  The author(s) assume no
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.\" 2005-09-15, mtk, Created new page by splitting off from sigaction.2
.\"
.TH SIGSUSPEND 2 2008-08-29 "Linux" "Linux Programmer's Manual"
.SH NAME
sigsuspend \- wait for a signal
.SH SYNOPSIS
.B #include <signal.h>
.sp
.BI "int sigsuspend(const sigset_t *" mask );
.sp
.in -4n
Feature Test Macro Requirements for glibc (see
.BR feature_test_macros (7)):
.in
.sp
.ad l
.BR sigsuspend ():
_POSIX_C_SOURCE\ >=\ 1 || _XOPEN_SOURCE || _POSIX_SOURCE
.ad b
.SH DESCRIPTION
.BR sigsuspend ()
temporarily replaces the signal mask of the calling process with the
mask given by
.I mask
and then suspends the process until delivery of a signal whose
action is to invoke a signal handler or to terminate a process.

If the signal terminates the process, then
.BR sigsuspend ()
does not return.
If the signal is caught, then
.BR sigsuspend ()
returns after the signal handler returns,
and the signal mask is restored to the state before the call to
.BR sigsuspend ().

It is not possible to block
.B SIGKILL
or
.BR SIGSTOP ;
specifying these signals in
.IR mask ,
has no effect on the process's signal mask.
.SH "RETURN VALUE"
.BR sigsuspend ()
always returns \-1, normally with the error
.BR EINTR .
.SH ERRORS
.TP
.B EFAULT
.I mask
points to memory which is not a valid part of the process address space.
.TP
.B EINTR
The call was interrupted by a signal.
.SH "CONFORMING TO"
POSIX.1-2001.
.SH NOTES
.PP
Normally,
.BR sigsuspend ()
is used in conjunction with
.BR sigprocmask (2)
in order to prevent delivery of a signal during the execution of a
critical code section.
The caller first blocks the signals with
.BR sigprocmask (2).
When the critical code has completed, the caller then waits for the
signals by calling
.BR sigsuspend ()
with the signal mask that was returned by
.BR sigprocmask (2)
(in the
.I oldset
argument).
.PP
See
.BR sigsetops (3)
for details on manipulating signal sets.
.SH "SEE ALSO"
.BR kill (2),
.BR pause (2),
.BR sigaction (2),
.BR signal (2),
.BR sigprocmask (2),
.BR sigwaitinfo (2),
.BR sigsetops (3),
.BR sigwait (3),
.BR signal (7)
.SH COLOPHON
This page is part of release 3.22 of the Linux
.I man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
