Examples of inter process communication(IPC)

I am wondering about actual examples or instances of inter process communication (IPC) which we encounter on a daily basis (which happen under the hood or othe开发者_运维问答rwise) while using our laptop/desktop. I have always read about these theoretically from a textbook.

For example:

• Between a parent process and child processes: one example of this in Linux I know is when a shell starts other processes and we can kill those processes using their process IDs.

• Between two unrelated (in hierarchy) but cooperating processes?

One way of doing IPC on the two cases you mentioned is using sockets.

I recommend taking a look at Beej's Guide to Unix Interprocess Communication for information and examples.

Some examples of IPC we encounter on a daily basis:

• X applications communicate with the X server through network protocols.
• Pipes are a form of IPC: grep foo file | sort
• Servers like Apache spawn child processes to handle requests.
• many more I can't think of right now

And I am not even mentioning examples of IPC where the processes are on different computers.