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How can I detect parent process death in Linux OS?
If in parent process called fork(), that create child process. In the parent process I can use system call wait() for waiting terminated child process, and getting its status.
But, I can't find info about how child process can detect parent process' death?
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When a parent process dies before a child process, the kernel knows that it's not going to get a wait call, so instead it makes these processes "orphans" and puts them under the care of init (remember mother of all processes).
Use getpid() and getppid() function to get process id and parent process id.
The pgrep and ps commands are useful in finding the direct child processes of a parent process. The pstree command lists all of the direct and indirect child processes in a tree structure. We can also find the child processes of a parent process in the /proc file system recursively.
In computing, a parent process is a process that has created one or more child processes.
You can get the parent process id by calling getppid() and then sending signal 0 via kill(). A return code of 0 will indicate that the process is still alive.
As mentioned by @Ariel, getppid() will either return the pid of the original parent or that of init, which will be pid 1. So you either have to store the parent pid by calling getppid() at startup or later check if your parent has pid 1.
According to this answer on Linux you can also detect the death of the parent via prctl()'s PR_SET_PDEATHSIG option and a self-chosen signal.
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