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NAME
_exit — terminate the calling process
LIBRARY
Standard C Library (libc, -lc)
SYNOPSIS
#include <unistd.h> void _exit(int status);
DESCRIPTION
The _exit() system call terminates a process with the following consequences:
• All of the descriptors open in the calling process are closed. This may entail delays, for example,
waiting for output to drain; a process in this state may not be killed, as it is already dying.
• If the parent process of the calling process has an outstanding wait(2) call or catches the SIGCHLD
signal, it is notified of the calling process's termination and the status is set as defined by
wait(2).
• The parent process-ID of all of the calling process's existing child processes are set to the process-
ID of the calling process's reaper; the reaper (normally the initialization process) inherits each of
these processes (see procctl(2), init(8) and the DEFINITIONS section of intro(2)).
• If the termination of the process causes any process group to become orphaned (usually because the
parents of all members of the group have now exited; see “orphaned process group” in intro(2)), and if
any member of the orphaned group is stopped, the SIGHUP signal and the SIGCONT signal are sent to all
members of the newly-orphaned process group.
• If the process is a controlling process (see intro(2)), the SIGHUP signal is sent to the foreground
process group of the controlling terminal, and all current access to the controlling terminal is
revoked.
Most C programs call the library routine exit(3), which flushes buffers, closes streams, unlinks temporary
files, etc., before calling _exit().
RETURN VALUES
The _exit() system call can never return.
SEE ALSO
fork(2), sigaction(2), wait(2), exit(3), init(8)
STANDARDS
The _exit() system call is expected to conform to ISO/IEC 9945-1:1990 (“POSIX.1”).
HISTORY
The _exit() function appeared in Version 7 AT&T UNIX.