Question

The sources from where the signals can be generated are:

(a) keyboard

(b) hardware

(c) a C program

(d) keyboard, hardware, a C program

I had been asked this question in an interview.

This intriguing question comes from Process Control System Calls in chapter System Programming II – Process Control & Unix System Performance of Unix

Answer 1

The correct choice is (d) keyboard, hardware, a C program

To explain I would say: The event that generates the signal can take place in the hardware, in the OS or elsewhere. It can be generated from the keyboard eg; SIGINT signal or it can be generated from the hardware eg; SIGILL.