Linux signals
Table of Contents
Signals #
- signals are used to notify processes about events in Inter Process Communication
- signal is an asynchronous event:
- not expected
- expected, but the time is not know
- signals are sent from the kernel or from a user process via system call with
kill
- user can send signal to his own processes
- root can send signal to any process
- signals can be handled differently by the programmer or resbond according to the system defaults
- two signal always use the system default: SIGKILL and SIGSTOP
- signal has a type and the type is indicate the meaning of the signal
- signals handle:
- exceptions detected by the hardware
- exceptions generated by the environment
- when signal sent from the kernel: the meaning attached to the signal
- The full list if signals
- SIGTERM: kills the process gracefully
- SIGKILL: kills the process immediately
- SIGRTMIN:
- no predefined purpose
- can be stacked, handled in FIFO
Reference #
- LFS201 (this is just my note from LFS201, not meant to replace the original, which is explain better the above)