less2sass multiple files https://rubygems.org/gems/less2sass

less2sass.sh

# script by github.com/jnaklaas
# base script by github.com/dunckr: https://gist.github.com/dunckr/1e149d5decf1f02e4fb9
LESS_PATH=${1:-"./"}
SASS_PATH=${2:-$LESS_PATH}
mkdir -p $SASS_PATH

for filename in $LESS_PATH*.less; do
    DESTINATION=$SASS_PATH"_`basename $filename .less`.scss"
    echo "less2sass $filename to $DESTINATION"
    less2sass "${filename}" $DESTINATION; 
done

Execute like this:

$ sh less2sass.sh less/ sass/

If you need your sass files in the same folder:

$ sh less2sass.sh less/