You press Ctrl+Z while a long-running command occupies the foreground of your bash shell. What happens?
LPIC-1 Exam 101-500, objective 103. GNU and Unix commands easy
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The options
Not correct The job continues in the background immediately.
Wrong. Ctrl+Z only suspends. You must then run `bg` to let the stopped job continue in the background.
Not correct The job is terminated by SIGINT.
Wrong. SIGINT is what Ctrl+C sends, and it normally terminates the foreground job rather than suspending it.
Not correct The job keeps running but is detached from the terminal.
Wrong. Nothing is detached; the job is stopped and consumes no CPU. Detaching from the terminal is what nohup, disown or a screen/tmux session do.
Correct The job is stopped (suspended) and control returns to the shell prompt.
Correct. Ctrl+Z sends SIGTSTP, which suspends the job. It appears in `jobs` as Stopped and can be resumed with fg or bg.
Why
Ctrl+Z sends SIGTSTP and the job stops. `jobs` lists it, `bg %1` resumes it in the background, `fg %1` brings it back to the foreground. A stopped job is frozen — it makes no progress until it receives SIGCONT via bg or fg.
Where this comes from
- Cited
- LPI exam objective 103.5
- What it says
- Manage background and foreground jobs with jobs, bg and fg.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 103 and space the ones you get wrong.