What's wrong with this Bourne shell script?

[Maarten Litmaath]

In article <3821 at auspex.auspex.com>,
	guy at auspex.auspex.com (Guy Harris) writes:
)...
)The Bourne shell runs some shell constructs in a sub-shell; apparently,
)the construct you gave is one of them.  [...]

[The construct was ``command | while read line; do something; done''.]

)This may change when shells become compliant with POSIX 1003.2, which
)will presumably happen sometime after POSIX 1003.2 leaves the draft
)stage and is approved; 1003.2 may put stricter controls on when a shell
)may do something inside a subshell.  I don't have recent drafts handy;
)Maarten?

I haven't read Draft 10 yet, but I pleaded for the `while' loop from the
example to be run in the current shell instead of a subshell (if the user
wants a subshell he can always use parentheses).  The advantages are
obvious.

In any case, _redirected_ loops already must be run in the current shell,
notwithstanding the current practice in a lot of Bourne shell implementations
to create a subshell:

	var=before
	while read line
	do
		var=after
	done < file
	echo var=$var

This example will print `after' on POSIX 1003.2 conformant systems,
`before' on many current systems.
--
   "UNIX was never designed to keep people from doing stupid things, because
    that policy would also keep them from doing clever things."  (Doug Gwyn)