Signals and jobs

Questions 1 to 5 of 7

1. 1. Match each signal to what it does, as the lesson describes it.

   Choose the matching item for each row.

   SIGTERM (the default for kill)Choose…pauses the process, and it can be resumed laterresumes a process that is stoppedends the process at once, and the program cannot catch itasks the program to stop, so a handler can clean up firstSIGKILLChoose…pauses the process, and it can be resumed laterresumes a process that is stoppedends the process at once, and the program cannot catch itasks the program to stop, so a handler can clean up firstSIGTSTP (Ctrl+Z)Choose…pauses the process, and it can be resumed laterresumes a process that is stoppedends the process at once, and the program cannot catch itasks the program to stop, so a handler can clean up firstSIGCONTChoose…pauses the process, and it can be resumed laterresumes a process that is stoppedends the process at once, and the program cannot catch itasks the program to stop, so a handler can clean up first
2. 2. Match each signal to its effect.

   Choose the matching item for each row.

   SIGINT (Ctrl+C)Choose…stops the program and writes a core dump, a file with its memorystops the foreground program, which may catch it to clean upsent when the terminal closes, or to ask for a config reloadSIGHUPChoose…stops the program and writes a core dump, a file with its memorystops the foreground program, which may catch it to clean upsent when the terminal closes, or to ask for a config reloadSIGQUITChoose…stops the program and writes a core dump, a file with its memorystops the foreground program, which may catch it to clean upsent when the terminal closes, or to ask for a config reload
3. 3. A program ignores SIGTERM. Which command will still stop it?

   kill -CONT <PID>kill -TSTP <PID>kill -KILL <PID>kill -0 <PID>
4. 4. A background job was started with & from a plain script. Someone runs kill -INT <PID> on it and nothing happens. Why?

   SIGINT only works on programs started from the prompt, not from a scriptThe process has already finished, so there is nothing to signalkill -INT sends SIGTERM instead, and the program ignores SIGTERMThe process ignores SIGINT, because the shell started it without job control, so SIGTERM or SIGKILL is needed
5. 5. True or false: a program that catches SIGTERM can run its cleanup code before it exits.

   True, because the program's handler runs when SIGTERM arrives, and it can save files before it calls exitFalse, because SIGTERM always stops a program at once with no code running