Zombie and orphan processes

1. We know that in unix/linux, under normal circumstances, the child process is created by the parent process, and the child process is creating a new process.The termination of the child process and the running of the parent process are an asynchronous process, that is, the parent process can never predict when the child process will end.When a process finishes its work and terminates, its parent process needs to call the wait() or waitpid() system call to obtain the termination status of the child process.
2. Orphan process: A parent process exits while one or more of its child processes are still running, then those child processes will become orphaned.The orphan process will be adopted by the init process (process number 1), and the init process will complete the state collection work for them.
3. Zombie process: A process uses fork to create a child process. If the child process exits and the parent process does not call wait or waitpid to obtain the status information of the child process, the process descriptor of the child process is still stored in the system.Such processes are called zombie processes.