You run `kill 3120` with no other options. Which signal does the process receive?
LPIC-1 Exam 101-500, objective 103. GNU and Unix commands easy
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The options
Correct SIGTERM (15)
Correct. SIGTERM is the default signal for both the shell builtin and /bin/kill. It asks the process to shut down and can be caught, so the program may flush buffers and clean up first.
Not correct SIGKILL (9)
Wrong. SIGKILL is never the default; you must ask for it explicitly with -9 or -KILL. It is handled by the kernel, cannot be caught or ignored, and gives the process no chance to clean up.
Not correct SIGHUP (1)
Wrong. SIGHUP originally meant the controlling terminal went away; today many daemons are coded to reread their configuration on it. It is sent by kill only when you ask for -1 or -HUP.
Not correct SIGINT (2)
Wrong. SIGINT is what the terminal sends when you press Ctrl+C in the foreground job. kill can send it with -2, but it is not the default.
Why
kill without a signal sends SIGTERM (15), the polite request to terminate. Escalate to SIGKILL (9) only when a process ignores SIGTERM, because SIGKILL denies the process any chance to release locks, remove PID files or flush data.
Where this comes from
- Cited
- LPI exam objective 103.5
- What it says
- Send signals to processes with kill; know common signal names and numbers.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 103 and space the ones you get wrong.