[rename-seq] Rename files in sequence

rename-seq

#!/usr/bin/env bash
# Usage: {script} [--debug|-d] DIRECTORY [ PREFIX ]
#
#   --debug, -d  Run script in debug mode
#   --help, -h   Displays this help
#
# Report bugs to Henrique Moody <henriquemoody@gmail.com>
#

declare DEBUG_MODE=0

_help()
{
    sed -E 's/^#\s?(.*)/\1/g' "${0}" |
        sed -nE '/^Usage/,/^Report/p' |
        sed "s/{script}/$(basename "${0}")/g"
}

case "${1}" in

    --debug | -d)
        DEBUG_MODE=1
        shift
    ;;

    --help | -h)
        _help
        exit
    ;;

esac

if [[ -z "${1}" ]]; then
    _help 1>&2
    exit 1
fi

DIRECTORY="${1}"
if [ ! -d "${DIRECTORY}" ]; then
    echo "$(basename "${0}"): \`${DIRECTORY}\` is not a valid directory." 1>&2
    exit 2
else
    cd "${DIRECTORY}"
fi

INDEX=1
if [ "${2}" ]; then
    PREFIX="${2}"
else
    PREFIX=$(basename "${PWD}")
fi

COUNT="$(ls -1 | wc -l | awk '{print $1}' | wc -c | awk '{print $1}')"

ls -1 |
    sort |
    while read old_name; do

        number=$(printf "%0${COUNT}d" ${INDEX})
        extension=$(echo "${old_name}" | sed -E 's/.+\.(.+)/\1/g' | tr '[A-Z]' '[a-z]')
        new_name="${PREFIX}-${number}.${extension}"

        if [ -f "${new_name}" ]; then
            echo "File ${new_name} already exists" 1>&2
        elif [[ ${DEBUG_MODE} -eq 1 ]]; then
            echo "${old_name} -> ${new_name}"
        else
            mv -v "${old_name}" "${new_name}"
        fi

        let INDEX=${INDEX}+1

    done