sigsuspend - Atomically changes the set of blocked signals and waits for a
Standard C Library (libc.so, libc.a)
int sigsuspend (
const sigset_t *signal_mask );
Interfaces documented on this reference page conform to industry standards
sigsuspend(): XPG4, XPG4-UNIX
Refer to the standards(5) reference page for more information about indus-
try standards and associated tags.
Points to a set of signals.
The sigsuspend() function replaces the signal mask of the process (or
thread) with the set of signals pointed to by the signal_mask parameter,
and then suspends execution of the caller until delivery of a signal whose
action is either to execute a signal-catching function or to terminate the
process. The sigsuspend() function does not allow the SIGKILL or SIGSTOP
signals to be blocked. If a program attempts to block one of these sig-
nals, the sigsuspend() function gives no indication of the error; the ille-
gal request is simply ignored.
If delivery of a signal causes the process to terminate, the sigsuspend()
function does not return. If delivery of a signal causes a signal-catching
function to execute, the sigsuspend() function returns after the signal-
catching function returns, with the signal mask restored to the set that
existed prior to the call to the sigsuspend() function.
The sigsuspend() function sets the signal mask and waits for an unblocked
signal as one atomic operation. This means that signals cannot occur
between the operations of setting the mask and waiting for a signal. If a
program invokes sigprocmask(SIG_SETMASK) and sigpause() separately, a sig-
nal that occurs between these functions might not be noticed by sigpause().
In normal usage, a signal is blocked by using the
sigprocmask(SIG_BLOCK,...) or pthread_sigmask(...) function at the begin-
ning of a critical section. The process then determines whether there is
work for it to do. If no work is to be done, the process waits for work by
calling the sigsuspend() function with the mask previously returned by the
The sigpause() function is provided for compatibility with older UNIX sys-
tems; its function is a subset of the sigsuspend() function.
Since the sigsuspend() function suspends process execution indefinitely,
there is no successful completion return value. If a return occurs, -1 is
returned and errno is set to indicate the error.
The sigsuspend() function sets errno to the specified values for the fol-
[EINTR] A signal is caught by the calling process and control is returned
from the signal-catching function.
Functions: pause(3), sigaction(2), sigblock(2), sigprocmask(2), sigvec(2)