fork() to execute processes from bottom to up using wait()
fork() system call is used to create a process generally known as child process and the process that created it is known as parent process. Now, all the processes that are created using fork() runs concurrently. But what if we want the last process created to execute first and in this manner bottom to up execution such that parent process executes last.
This can be done by using wait() system call. The parent process may then issue a wait() system call, which suspends the execution of the parent process while the child executes and when the child finishes execution, it returns exit status to operating system. Now wait() suspend the process until any of its child process finish execution.
NOTE: This is a linux system call, so it must be executed on linux or unix variant system.
Grand Child Terminated 2nd Child Terminated 1st child Terminated Parent Terminated