1 Answers
In computer operating systems, a process may wait on another process to complete its execution. In most systems, a parent process can create an independently executing child process. The parent process may then issue a wait system call, which suspends the execution of the parent process while the child executes. When the child process terminates, it returns an exit status to the operating system, which is then returned to the waiting parent process. The parent process then resumes execution.
Modern operating systems also provide system calls that allow a process's thread to create other threads and wait for them to terminate in a similar fashion.
An operating system may provide variations of the wait call that allow a process to wait for any of its child processes to exit, or to wait for a single specific child process to exit.
Some operating systems issue a signal to the parent process when a child process terminates, notifying the parent process and allowing it to retrieve the child process's exit status.