shell misfeature

[utzoo!henry]

The following does not always do what you expect:

	PATH=/bin:/usr/bin
	... something ...

Why?  Because except in some situations where all programs involved are
shell files, the offspring will see the original PATH, not "/bin:/usr/bin".
Why so?  Because the change to PATH was not exported!  Of the people
here who have run into this "feature", 100% think that it is both
(a) counterintuitive and (b) wrong.

The rule that "no change is exported unless the variable is exported"
is elegant but is bad human engineering, because the "exported" status
of the variable is not passed down to children when the value is passed
down.  Even the shell doesn't consistently follow this rule, witness the
"except" in the first sentence above.  Proposal:  variables inherited
from the environment should be implicitly and automatically marked
"exported".  Does anybody see anything wrong/bad about this?

For an example of the trouble, the "PATH=/bin:/usr/bin;" that uuxqt
prepends to every command it runs is not inherited by the command.