|SIGWAIT(2)||System Calls Manual||SIGWAIT(2)|
sigwait — select a
set of signals
Standard C Library (libc, -lc)
sigset_t * restrict set,
int * restrict sig);
system call selects a set of signals, specified by
set. If none of the selected signals are pending,
sigwait() waits until one or more of the selected
signals has been generated. Then
atomically clears one of the selected signals from the set of pending
signals (for the process or for the current thread) and sets the location
pointed to by sig to the signal number that was
The signals specified by set
should be blocked at the time of the call to
If more than one thread is using
to wait for the same signal, no more than one of these threads will return
sigwait() with the signal number. If more than
a single thread is blocked in
sigwait() for a signal
when that signal is generated for the process, it is unspecified which of
the waiting threads returns from
sigwait(). If the
signal is generated for a specific thread, as by
only that thread will return.
Should any of the multiple pending signals in the range
selected, it will be the lowest numbered one. The selection order between
realtime and non-realtime signals, or between multiple pending non-realtime
signals, is unspecified.
sigwait() function is implemented as a
wrapper around the
__sys_sigwait() system call,
which retries the call on
sigwait() returns 0 and
sets the location pointed to by sig to the cleared
signal number. Otherwise, an error number is returned.
sigwait() system call will fail
- The set argument specifies one or more invalid signal numbers.
sigwait() function conforms to
ISO/IEC 9945-1:1996 (“POSIX.1”).
|September 6, 2013||Debian|