www.delorie.com/gnu/docs/glibc/libc_504.html

search

	Buy the book!

The GNU C Library

24.7 Blocking Signals

Blocking a signal means telling the operating system to hold it and deliver it later. Generally, a program does not block signals indefinitely--it might as well ignore them by setting their actions to SIG_IGN. But it is useful to block signals briefly, to prevent them from interrupting sensitive operations. For instance:

• You can use the sigprocmask function to block signals while you modify global variables that are also modified by the handlers for these signals.

• You can set sa_mask in your sigaction call to block certain signals while a particular signal handler runs. This way, the signal handler can run without being interrupted itself by signals.

24.7.1 Why Blocking Signals is Useful		The purpose of blocking signals.
24.7.2 Signal Sets		How to specify which signals to block.
24.7.3 Process Signal Mask		Blocking delivery of signals to your process during normal execution.
24.7.4 Blocking to Test for Delivery of a Signal
24.7.5 Blocking Signals for a Handler		Blocking additional signals while a handler is being run.
24.7.6 Checking for Pending Signals
24.7.7 Remembering a Signal to Act On Later		How you can get almost the same effect as blocking a signal, by handling it and setting a flag to be tested later.