The exit utility shall cause the shell to exit with the exit status specified by the unsigned decimal integer n. 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.
See the DESCRIPTION.
The standard error shall be used only for diagnostic messages.
The exit status shall be n, if specified. 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.
The following sections are informative.
Exit with a true value:
Exit with a false value:
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:
A file to be executed was found, but it was not an executable utility.
A utility to be executed was not found.
A command was interrupted by a signal.
Special Built-In Utilities
Portions of this text are reprinted and reproduced in electronic form from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable Operating System Interface (POSIX), The Open Group Base Specifications Issue 6, Copyright (C) 2001-2003 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 .