Which of the following option with reference to UNIX operating system is not…
2016
Which of the following option with reference to UNIX operating system is not correct ?
- A.
INT signal is sent by the terminal driver when one types and it is a request to terminate the current operation.
- B.
TERM is a request to terminate execution completely. The receiving process will clean up its state and exit.
- C.
QUIT is similar to TERM, except that it defaults to producing a core dump if not caught.
- D.
KILL is a blockable signal.
Attempted by 27 students.
Show answer & explanation
Correct answer: D
Answer: The statement "KILL is a blockable signal." is not correct.
SIGINT (interrupt): Sent by the terminal driver when the user types the interrupt character (usually Ctrl-C). It requests interruption of the current foreground operation; processes can catch or handle it.
SIGTERM (terminate): A polite request to terminate execution. The receiving process can catch SIGTERM, perform cleanup, and then exit.
SIGQUIT (quit): Similar to SIGTERM but by default produces a core dump if not caught. Commonly generated by typing Ctrl-\ in a terminal.
SIGKILL (kill): Cannot be caught, blocked, or ignored. It forcefully terminates a process immediately and the process cannot perform cleanup. Therefore it is not blockable.
Conclusion: The incorrect statement is the claim that KILL is a blockable signal, because SIGKILL is uncatchable and unblockable.