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



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

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(1)
