Rename files by date. (OSX, only)

rename-by-date.bash

#!/usr/bin/env bash
# Usage: {script} FILE1 FILE2 ...
#
#   --help, h   Displays this help
#
# Report bugs to Henrique Moody <henriquemoody@gmail.com>
#

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

_rename_by_date()
{
    file_creation=$(
        stat -t "%Y-%m-%d_%H.%M.%S" "${1}" |
        sed 's/"//g' |
        awk '{print $10}' |
        sed 's/_/ /g'
    )
    file_extension=$(
        echo "${1}" |
        rev |
        cut -d . -f 1 |
        rev |
        tr "[:upper:]" "[:lower:]"
    )
    if [ "${file_extension}" == "jpeg" ] || [ -z "${file_extension}" ]; then
        file_extension="jpg"
    fi
    mv -vn "${1}" "${file_creation}.${file_extension}"
}

if [ ${#} -eq 0 ]; then
    _help 1>&2
    exit 1
fi

while [ ! -z "${1}" ]; do

    case "${1}" in

        --help | -h)
            _help
            exit 0
        ;;

        *)
            _rename_by_date "${1}"
            shift 1
        ;;

    esac

done