rename.sh

#!/bin/sh

# rename.sh [-n] [-r] <regex> [file [...]]

notreally=
sedopts=

while getopts ":nr" opt ; do
    case $opt in
        n)
            notreally=y
        ;;
        r)
            sedopts=-r
        ;;
        \?)
            echo "Invalid option: -$OPTARG" >&2
            exit 1
        ;;
        :)
            echo "Option -$OPTARG requires an argument." >&2
        ;;
        *)
            echo "Arg: $opt" >&2
        ;;
    esac
done

shift $(($OPTIND - 1))

if [ -z "$1" ] ; then
    echo "No regex specified." >&2
    exit 1
fi
regex=$1
shift

if [ -z "$notreally" ] ; then
    while [ -n "$1" ] ; do
        mv "$1" "$(echo "$1" | sed $sedopts "$regex")"
        shift
    done
else
    while [ -n "$1" ] ; do
        echo "\"$1\"" "->" "\"$(echo "$1" | sed $sedopts "$regex")\""
        shift
    done
fi