RSS feeds
User login
All about Linux signals
Table of Contents:
- All about Linux signals
- Introduction
- What is signaled, signal handlers
- Handling specific signals: SIGCHLD, SIGBUS, SIGSEGV, SIGABRT
- What happens when a process receives a signal, system call interruption
- Blocking signals
- Waiting for a signal
- Sending signals
- Real-time signals
- Signals and fork()
- Signals and threads
- Other uses of signals
- That's not everything!
Other uses of signals
Here I'll present non-traditional uses of signals, but mainly for historical reasons. We have better mechanisms to do the same things now, but it might be interesting that signals may be used this way.
It's possible to be notified of I/O availability by a signal. It's an alternative to functions like select(2). It's done by setting the O_ASYNC flag on the file descriptor. If you do so and if I/O is available (as select(2) would consider it) a signal is sent to the process. By default it's SIGIO, but using Real-time signals is more practical and you can set up the file descriptor using fcntl(2) so that you get more information in siginfo_t structure. See the links at the bottom of this article for more information. There is now a better way to do it on Linux: epoll(7) and similar mechanisms are available on other systems.
The dnotify mechanism uses similar technique: you are notified about file system actions using signals related to file descriptors of monitored directories or files. The recommended way of monitoring files is now inotify.
Hi, typo jerk here
Thanks. I don't consider it
I was looking for linux
Great write-up
Signals - That's not everything