Bourne shell oddity

[SILL D E]

What should the following script do?

#!/bin/sh
foo=bar
while true
do
    if [ $foo = bar ]
    then
        foo=baz
        echo foo=${foo}
        break
    fi
done </dev/null
echo foo=${foo}

I would have expected it to output:

foo=baz
foo=baz

But I get:

foo=baz
foo=bar

Removing the input redirection from the while-loop gives the expected
result. 

Question:  Is this a bug, or is I/O redirection of commands supposed
to affect variable scoping somehow?  I couldn't find anything in the
FM to explain this behavior.

Another Question:  Is there a simple workaround, preferably something
more elegant than passing values in files?

Please reply by mail; I don't follow this group/list.

Thanks.

--
Dave Sill (de5 at ornl.gov)
Martin Marietta Energy Systems
Workstation Support