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(1POSIX)