exit(S)

Synopsis

   #include <stdlib.h>
   

   void exit(int status);
   

   #include <unistd.h>
   

   void _exit(int status);
   

   #include <unistd.h>
   

   void _Exit(int status);

Description

• All of the file descriptors, directory streams and message catalogue descriptors open in the calling process are closed.

• A SIGCHLD signal is sent to the calling process's parent process.

• If the parent process of the calling process has not specified the SA_NOCLDWAIT flag [see sigaction(S)], the calling process is transformed into a ``zombie process.'' A zombie process is a process that only occupies an entry in the process list. It has no other space allocated either in user or kernel space. The process table slot that it occupies is partially overlaid with time accounting information [see <sys/proc.h>] to be used by the times system call.

• The parent process ID of all of the calling process's existing child processes and zombie processes is set to 1. This means the initialization process [see intro(S)] inherits each of these processes.

• Each attached shared memory segment is detached and the value of shm_nattach in the data structure associated with its shared memory identifier is decremented by 1.

• For each semaphore for which the calling process has set a semadj value [see semop(S)], that semadj value is added to the semval of the specified semaphore.

• If the process has a process, text, or data lock, an unlock is performed [see plock(S)].

• An accounting record is written on the accounting file if the system's accounting routine is enabled [see acct(S)].

• If the process is a controlling process, SIGHUP is sent to the foreground process group of its controlling terminal and its controlling terminal is deallocated.

• If the calling process has any stopped children whose process group will be orphaned when the calling process exits, or if the calling process is a member of a process group that will be orphaned when the calling process exits, that process group will be sent SIGHUP and SIGCONT signals.

The C function exit calls any functions registered through the atexit function in the reverse order of their registration. The _exit and _Exit functions circumvent all such functions and cleanup. (Note also that if a process receives a signal that has an action of Exit or Core, the functions registered with atexit are not called. See signal(M).)

The symbols EXIT_SUCCESS and EXIT_FAILURE are defined in stdlib.h and may be used as the value of status to indicate successful or unsuccessful termination, respectively. The low-order 8 bits of status is available through wait(S) (and similar functions).

References

Notices

Considerations for threads programming

Considerations for lightweight processes