Programming

Assume we have an application built on *nix that uses fork()...then the processes procedure is going to act as follow:

X is considered a parent process (first click on application)
Y is considered a child process of X (second click on application)
Z is considered a child process of Y (third click on application)

If Y terminates, signal is sent to X to let X knows that Y is exited...
If Z terminates, signal is sent to Y (parent process of Z) to let Y knows that Z is exited...

1. Right?

2. If yes, then why Z exits status is not returned to X? Why not all exit status get returned to the very first parent process?

The very first parent process is not your program, it's init, the startup program UNIX runs on boot to create all other processses. I doubt you want your signals to end up there. Though if the parent dies before the child does, that is where the child's signal will end up.

ha ok, i see. orphan child signal will end up to init....

so it goes like

init()
X
y
Z

X is parent of Y. X is child of init().....

So lets say i opened a browser in *nix. This browser is multi-process.
First browser opened (X) is going to be a child on init()
Second browser (Y) opened, is going to be a child of (X).
X will take care of Y. If X dies, init() takes care of Y..

I hope this is right. I would like somebody to confirm!

Many THANKS!!!

If you open two browsers, they'd be two children of the same parent, not one as the parent of the other.

There's also more layers than init -> user application -> children, though that's enough for examples. Init creates the window server which creates the login manager which creates everything you run; or for a shell, init creates the login shell which creates your processes.

I see...

I made my assumption based on this quote:

"Every process has one parent process. Parent process always has many child processes. and every child process can create another new child process which makes the first child process becomes a parent to the new child process, and in the same time it is considered a child process to its parent process. It is like a parent creates a child and child creates a new child! so the new child process has a parent of a child process who got another parent. It goes like a chain. Parent process does not *always* have many child process only when it forks them."

Thats why i thought second browser is a child of the first browser...

That paragraph isn't written very clearly. If a process created a process, the old process is that new process' parent, it's that simple.

alright....thanks! i got it