exit(1p) — Linux manual page

EXIT(1P)                POSIX Programmer's Manual               EXIT(1P)

PROLOG

       This manual page is part of the POSIX Programmer's Manual.  The
       Linux implementation of this interface may differ (consult the
       corresponding Linux manual page for details of Linux behavior),
       or the interface may not be implemented on Linux.

NAME

       exit — cause the shell to exit

SYNOPSIS

       exit [n]

DESCRIPTION

       The exit utility shall cause the shell to exit from its current
       execution environment with the exit status specified by the
       unsigned decimal integer n.  If the current execution environment
       is a subshell environment, the shell shall exit from the subshell
       environment with the specified exit status and continue in the
       environment from which that subshell environment was invoked;
       otherwise, the shell utility shall terminate with the specified
       exit status. If n is specified, but its value is not between 0
       and 255 inclusively, the exit status is undefined.

       A trap on EXIT shall be executed before the shell terminates,
       except when the exit utility is invoked in that trap itself, in
       which case the shell shall exit immediately.

OPTIONS

       None.

OPERANDS

       See the DESCRIPTION.

STDIN

       Not used.

INPUT FILES

       None.

ENVIRONMENT VARIABLES

       None.

ASYNCHRONOUS EVENTS

       Default.

STDOUT

       Not used.

STDERR

       The standard error shall be used only for diagnostic messages.

OUTPUT FILES

       None.

EXTENDED DESCRIPTION

       None.

EXIT STATUS

       The exit status shall be n, if specified, except that the
       behavior is unspecified if n is not an unsigned decimal integer
       or is greater than 255. Otherwise, the value shall be the exit
       value of the last command executed, or zero if no command was
       executed. When exit is executed in a trap action, the last
       command is considered to be the command that executed immediately
       preceding the trap action.

CONSEQUENCES OF ERRORS

       Default.

       The following sections are informative.

APPLICATION USAGE

       None.

EXAMPLES

       Exit with a true value:

           exit 0

       Exit with a false value:

           exit 1

       Propagate error handling from within a subshell:

           (
               command1 || exit 1
               command2 || exit 1
               exec command3
           ) > outputfile || exit 1
           echo "outputfile created successfully"

RATIONALE

       As explained in other sections, certain exit status values have
       been reserved for special uses and should be used by applications
       only for those purposes:

        126    A file to be executed was found, but it was not an
               executable utility.

        127    A utility to be executed was not found.

       >128    A command was interrupted by a signal.

       The behavior of exit when given an invalid argument or unknown
       option is unspecified, because of differing practices in the
       various historical implementations. A value larger than 255 might
       be truncated by the shell, and be unavailable even to a parent
       process that uses waitid() to get the full exit value. It is
       recommended that implementations that detect any usage error
       should cause a non-zero exit status (or, if the shell is
       interactive and the error does not cause the shell to abort,
       store a non-zero value in "$?"), but even this was not done
       historically in all shells.

FUTURE DIRECTIONS

       None.

SEE ALSO

       Section 2.14, Special Built-In Utilities

COPYRIGHT

       Portions of this text are reprinted and reproduced in electronic
       form from IEEE Std 1003.1-2017, Standard for Information
       Technology -- Portable Operating System Interface (POSIX), The
       Open Group Base Specifications Issue 7, 2018 Edition, Copyright
       (C) 2018 by the Institute of Electrical and Electronics
       Engineers, Inc and The Open Group.  In the event of any
       discrepancy between this version and the original IEEE and The
       Open Group Standard, the original IEEE and The Open Group
       Standard is the referee document. The original Standard can be
       obtained online at http://www.opengroup.org/unix/online.html .

       Any typographical or formatting errors that appear in this page
       are most likely to have been introduced during the conversion of
       the source files to man page format. To report such errors, see
       https://www.kernel.org/doc/man-pages/reporting_bugs.html .

IEEE/The Open Group               2017                          EXIT(1P)

Pages that refer to this page: return(1p), sh(1p)

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