C++ || Snippet – How To Use Fork & Pipe For Interprocess Communication

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The following is sample code which demonstrates the use of the fork, read, and write function calls for use with pipes on Unix based systems.

A pipe is a mechanism for interprocess communication. Data written to a pipe by one process can be read by another process. Creating a pipe is achieved by using the pipe function, which creates both the reading and writing ends of the pipe file descriptor.

In typical use, a parent process creates a pipe just before it forks one or more child processes. The pipe is then used for communication between either the parent or child processes, or between two sibling processes.

A real world example of this kind of communication can be seen in all operating system terminal shells. When you type a command in a shell, it will spawn the executable represented by that command with a call to fork. A pipe is opened to the new child process, and its output is read and printed by the terminal.


QUICK NOTES:
The highlighted lines are sections of interest to look out for.

The code is heavily commented, so no further insight is necessary. If you have any questions, feel free to leave a comment below.

The following is sample output:

Parent is forking a child.
Parent is now waiting for child id #12776 to complete..

Starting the child process..

Message from the parent via the pipe: Greetings From Your Parent!

Program is now exiting...

The child process is complete and has terminated!

Program is now exiting...

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