Exit status
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The exit status of a process in computer programming is a small number passed from a child process to a parent process when it is done executing a specific task delegated.
When software programs are run or executed, the operating system creates an abstract entity called a computer process in which all the book-keeping for that program is done. In multitasking operating systems such as UNIX or Linux, new processes can be created by active processes. Such processes are parent processes while those created are child processes. It is common in programming for a parent process to delegate some work to a child process it creates while it may remain busy with something else. When the child is done executing, it will exit by calling the exit system call. This system call facilitates passing a small number back to the parent, which can retrieve this value using the wait system call. This is the exit status of the child.
The parent and the child can have an understanding about the meaning of the exit statuses. For example, it is common programming practice for a child process to return zero to the parent signifying success. Apart from this return value from the child, other information like how the process exited, either normally or by a signal is also available to the parent process.
