EXIT(S) UNIX System V EXIT(S)
Name
exit, _exit - terminate process
Syntax
void exit (status)
int status;
void _exit (status)
int status;
Description
The exit system call terminates the calling process with the
following consequences:
All of the file descriptors open in the calling process are
closed.
If the parent process of the calling process is executing a
wait, it is notified of the calling process's termination
and the low order eight bits (that is, bits 0377) of status
are made available to it (see wait(S)).
If the parent process of the calling process is not
executing a wait, the calling process is transformed into a
zombie process. A zombie process is a process that only
occupies a slot in the process table. 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
times.
The parent process ID of all of the calling processes'
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 ID, tty group ID, and process group ID of the
calling process are equal, the SIGHUP signal is sent to each
process that has a process group ID equal to that of the
calling process.
A death of child signal is sent to the parent.
The C function exit may cause cleanup actions before the
process exits. The function _exit circumvents all cleanup.
See Also
acct(S), intro(S), plock(S), semop(S), signal(S), sigset(S),
wait(S)
Diagnostics
None. There can be no return from an exit system call.
Standards Conformance
_exit is conformant with:
The X/Open Portability Guide II of January 1987;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
exit is conformant with:
The X/Open Portability Guide II of January 1987;
ANSI X3.159-198X C Language Draft Standard, May 13, 1988;
IEEE POSIX Std 1003.1-1988 with C Standard Language-
Dependent System Support;
and NIST FIPS 151-1.
(printed 6/20/89)