How to make child process die after parent exits?

Question

Suppose I have a process which spawns exactly one child process. Now when the parent process exits for whatever reason (normally or abnormally, by kill, ^C, assert failure or anything else) I want the child process to die. How to do that correctly?

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Some similar question on stackoverflow:

• (asked earlier) How can I cause a child process to exit when the parent does?
• (asked later) Are child processes created with fork() automatically killed when the parent is killed?

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Some similar question on stackoverflow for Windows:

• How do I automatically destroy child processes in Windows?
• Kill child process when parent process is killed

Answer 1

Child can ask kernel to deliver SIGHUP (or other signal) when parent dies by specifying option PR_SET_PDEATHSIG in prctl() syscall like this:

prctl(PR_SET_PDEATHSIG, SIGHUP);

See man 2 prctl for details.

Edit: This is Linux-only