Exit (system call)On many computer operating systems, a computer process terminates its execution by making an exit system call. More generally, an exit in a multithreading environment means that a thread of execution has stopped running. For resource management, the operating system reclaims resources (memory, , etc.) that were used by the process. The process is said to be a dead process after it terminates. Under Unix and Unix-like operating systems, a process is started when its parent process executes a fork system call.
Exec (system call)In computing, exec is a functionality of an operating system that runs an in the context of an already existing process, replacing the previous executable. This act is also referred to as an overlay. It is especially important in Unix-like systems, although it exists elsewhere. As no new process is created, the process identifier (PID) does not change, but the machine code, data, heap, and stack of the process are replaced by those of the new program.
Wait (system call)In computer operating systems, a process (or task) may wait for 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.
Processus zombieEn informatique, sous les systèmes de type UNIX et similaires, zombie (on utilise plutôt l'orthographe anglaise) est un terme désignant un processus qui s'est achevé, mais qui dispose toujours d'un identifiant de processus (PID) et reste donc encore visible dans la table des processus. On parle aussi de processus défunt (en anglais "defunct"). Au moment de la terminaison d'un processus, le système désalloue les ressources que possède encore le processus mais ne détruit pas son bloc de contrôle.
