for MATCHES in $(grep -i -R -e "head -[ 0-9]" -e "tail [+-][ 0-9]" * | cut -f1 -d: | sort -u) ; do
        mv ${MATCHES} ${MATCHES}.orig
        sed -e 's/head -\(.*\)/head -n \1/' \
        -e 's/tail \([-+]\)\(.*\)/tail -n \1\2/'\
        < ${MATCHES}.orig \
        > ${MATCHES}
        rm ${MATCHES}.orig
done