Ash eval wierdness

[Nigel Hathaway]

I'm trying to import a set of variables from a file containing assignments of the form "a=b", one on each line. I am finding that the variable assignments are being lost.

Here is a simplified version of my script which illustrates the problem:

echo "myvar=my value" | while read opt; do 
    if echo "$opt" | grep -q '='; then
        var=`echo "$opt" | /bin/sed "s/=.*//"`
        val=`echo "$opt" | /bin/sed "s/[^=]*=//"`
        eval $var=\'$val\'
        echo "(1)" $var=\'$val\'
        echo "(2) myvar=$myvar"
    fi
done
echo "(3) myvar=$myvar"

Which yields this:

(1) myvar='my value'
(2) myvar=my value
(3) myvar=

I am using Busybox v1.18.4

Any idea what is going on?