Next: Problems with
pause, Up: Waiting for a Signal [Contents][Index]
The simple way to wait until a signal arrives is to call
Please read about its disadvantages, in the following section, before
you use it.
Preliminary: | MT-Unsafe race:sigprocmask/!bsd!linux | AS-Unsafe lock/hurd | AC-Unsafe lock/hurd | See POSIX Safety Concepts.
pause function suspends program execution until a signal
arrives whose action is either to execute a handler function, or to
terminate the process.
If the signal causes a handler function to be executed, then
pause returns. This is considered an unsuccessful return (since
“successful” behavior would be to suspend the program forever), so the
return value is
-1. Even if you specify that other primitives
should resume when a system handler returns (see Primitives Interrupted by Signals), this has no effect on
pause; it always fails when a
signal is handled.
errno error conditions are defined for this function:
The function was interrupted by delivery of a signal.
If the signal causes program termination,
pause doesn’t return
This function is a cancellation point in multithreaded programs. This
is a problem if the thread allocates some resources (like memory, file
descriptors, semaphores or whatever) at the time
called. If the thread gets cancelled these resources stay allocated
until the program ends. To avoid this calls to
pause should be
protected using cancellation handlers.
pause function is declared in unistd.h.