CVS commit: src/bin/sh

["Robert Elz" <kre%netbsd.org@localhost>]

Module Name:    src
Committed By:   kre
Date:           Tue Dec  4 14:03:30 UTC 2018

Modified Files:
        src/bin/sh: sh.1 var.c var.h

Log Message:
Alter a design botch when magic (self modifying) variables
were added to sh ... in other shells, setting such a variable
(for most of them) causes it to lose its special properties,
and act the same as any other variable.   I had assumed that
was just implementor laziness...   I was wrong.

>From now on the NetBSD shell will act like the others, and if vars
like HOSTNAME (and SECONDS, etc) are used as variables in a script
or whatever, they will act just like normal variables (and unless
this happens when they have been made local, or as a variable-assignment
as a prefix to a command, the special properties they would have had
otherwise are lost for the remainder of the life of the (sub-)shell
in which the variables were set).

Importing a value from the environment counts as setting the
value for this purpose (so if HOSTNAME is set in the environment,
the value there will be the value $HOSTNAME expands to).

The two exceptions to this are LINENO and RANDOM.   RANDOM
needs to be able to be set to (re-)set its seed.  LINENO needs to
be able to be set (at least in the "local" command) to achieve
the desired functionality.   It is unlikely that any (sane) script
is going to want to use those two as normal vars however.

While here, fix a minor bug in popping local vars (fn return) that need
to notify the shell of changes in value (like PATH).

Change sh(1) to reflect this alteration.  Also add doc of the
(forgotten) magic var EUSER (which has been there since the others
were added), and add a few more vars (which are documented
in other places in sh(1) - like ENV) into the defined or used
variable list (as well as wherever else they appear).

XXX pullup -8


To generate a diff of this commit:
cvs rdiff -u -r1.210 -r1.211 src/bin/sh/sh.1
cvs rdiff -u -r1.71 -r1.72 src/bin/sh/var.c
cvs rdiff -u -r1.37 -r1.38 src/bin/sh/var.h

Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.