mirror of https://github.com/mkerrisk/man-pages
168 lines
4.5 KiB
Groff
168 lines
4.5 KiB
Groff
.\" Copyright (C) 2001 Andries Brouwer <aeb@cwi.nl>.
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.\"
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.\" Permission is granted to make and distribute verbatim copies of this
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.\" manual provided the copyright notice and this permission notice are
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.\" preserved on all copies.
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.\"
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.\" Permission is granted to copy and distribute modified versions of this
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.\" manual under the conditions for verbatim copying, provided that the
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.\" entire resulting derived work is distributed under the terms of a
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.\" permission notice identical to this one.
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.\"
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.\" Since the Linux kernel and libraries are constantly changing, this
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.\" manual page may be incorrect or out-of-date. The author(s) assume no
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.\" responsibility for errors or omissions, or for damages resulting from
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.\" the use of the information contained herein. The author(s) may not
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.\" have taken the same level of care in the production of this manual,
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.\" which is licensed free of charge, as they might when working
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.\" professionally.
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.\"
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.\" Formatted or processed versions of this manual, if unaccompanied by
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.\" the source, must acknowledge the copyright and authors of this work.
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.\"
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.TH EXIT 3 2007-06-12 "Linux" "Linux Programmer's Manual"
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.SH NAME
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exit \- cause normal process termination
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.SH SYNOPSIS
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.nf
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.B #include <stdlib.h>
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.sp
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.BI "void exit(int " status );
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.fi
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.SH DESCRIPTION
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The
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.BR exit ()
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function causes normal process termination and the
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value of \fIstatus & 0377\fP is returned to the parent
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(see
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.BR wait (2)).
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.LP
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All functions registered with
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.BR atexit (3)
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and
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.BR on_exit (3)
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are called, in the reverse order of their registration.
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(It is possible for one of these functions to use
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.BR atexit (3)
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or
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.BR on_exit (3)
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to register an additional
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function to be executed during exit processing;
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the new registration is added to the front of the list of functions
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that remain to be called.)
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If one of these functions does not return
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(e.g., it calls
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.BR _exit (2),
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or kills itself with a signal),
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then none of the remaining functions is called,
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and further exit processing (in particular, flushing of
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.BR stdio (3)
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streams) is abandoned.
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If a function has been registered multiple times using
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.BR atexit (3)
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or
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.BR on_exit (3),
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then it is called as many times as it was registered.
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.LP
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All open
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.BR stdio (3)
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streams are flushed and closed.
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Files created by
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.BR tmpfile (3)
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are removed.
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.LP
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The C standard specifies two constants,
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\fBEXIT_SUCCESS\fP and \fBEXIT_FAILURE\fP,
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that may be passed to
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.BR exit ()
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to indicate successful or unsuccessful
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termination, respectively.
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.SH "RETURN VALUE"
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The
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.BR exit ()
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function does not return.
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.SH "CONFORMING TO"
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SVr4, 4.3BSD, POSIX.1-2001, C89, C99.
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.SH NOTES
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.LP
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It is undefined what happens if one of the
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functions registered using
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.BR atexit (3)
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and
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.BR on_exit (3)
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calls either
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.BR exit ()
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or
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.BR longjmp (3).
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.LP
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The use of
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.B EXIT_SUCCESS
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and
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.B EXIT_FAILURE
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is slightly more portable
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(to non-Unix environments) than the use of 0 and some non-zero value
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like 1 or \-1.
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In particular, VMS uses a different convention.
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.LP
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BSD has attempted to standardize exit codes; see the file
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.IR <sysexits.h> .
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.LP
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After
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.BR exit (),
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the exit status must be transmitted to the
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parent process.
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There are three cases.
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If the parent has set
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.BR SA_NOCLDWAIT ,
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or has set the
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.B SIGCHLD
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handler to
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.BR SIG_IGN ,
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the status is discarded.
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If the parent was waiting on the child
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it is notified of the exit status.
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In both cases the exiting
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process dies immediately.
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If the parent has not indicated that
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it is not interested in the exit status, but is not waiting,
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the exiting process turns into a "zombie" process
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(which is nothing but a container for the single byte representing
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the exit status) so that the parent can learn the exit status when
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it later calls one of the
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.BR wait (2)
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functions.
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.LP
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If the implementation supports the
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.B SIGCHLD
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signal, this signal
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is sent to the parent.
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If the parent has set
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.BR SA_NOCLDWAIT ,
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it is undefined whether a
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.B SIGCHLD
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signal is sent.
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.LP
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If the process is a session leader and its controlling terminal
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is the controlling terminal of the session, then each process in
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the foreground process group of this controlling terminal
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is sent a
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.B SIGHUP
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signal, and the terminal is disassociated
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from this session, allowing it to be acquired by a new controlling
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process.
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.LP
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If the exit of the process causes a process group to become orphaned,
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and if any member of the newly orphaned process group is stopped,
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then a
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.B SIGHUP
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signal followed by a
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.B SIGCONT
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signal will be
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sent to each process in this process group.
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.SH "SEE ALSO"
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.BR _exit (2),
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.BR wait (2),
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.BR atexit (3),
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.BR on_exit (3),
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.BR tmpfile (3)
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