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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 .