The return utility shall cause the shell to stop executing the current function or dot script. If the shell is not currently executing a function or dot script, the results are unspecified.
See the DESCRIPTION.
The standard error shall be used only for diagnostic messages.
The value of the special parameter '?' shall be set to n, an unsigned decimal integer, or to the exit status of the last command executed if n is not specified. If the value of n is greater than 255, the results are undefined. When return 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
The following sections are informative.
The behavior of return when not in a function or dot script differs between the System V shell and the KornShell. In the System V shell this is an error, whereas in the KornShell, the effect is the same as exit.
The results of returning a number greater than 255 are undefined because of differing practices in the various historical implementations. Some shells AND out all but the low-order 8 bits; others allow larger values, but not of unlimited size.
See the discussion of appropriate exit status values under exit .
COPYRIGHTPortions 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 .