Give all the files in a directory incremental file names based on creation date. Example: img_000.jpg, img_001.jpg, etc.

incremental-filenames.sh

#!/bin/bash

set -e

NAME=$(basename ${0})
USAGE="Usage: ${NAME} source target [prefix]"

function error {
    echo "${NAME}: ${1:-'Unknown Error'}" 1>&2
    echo ${USAGE} 1>&2
    exit 1
}

if [ "${#}" -lt 2 ]; then
    error 'Not enough arguments.'
fi

SOURCE=$(basename "${1}")
TARGET=$(basename "${2}")
PREFIX=${3:-file}

if [ ! -d "${SOURCE}" ]; then
    error "Not a valid directory: ${SOURCE}"
    exit 1
fi

mkdir -p ${TARGET}

counter=0
files=$(ls -1Rrt ${SOURCE})
total=$(echo "${files}" | wc -l | bc)
total_radix=${#total}
indices=($(seq -f "%0${total_radix}g" 0 ${total}))
IFS='
'
for file in ${files}; do
    filename=$(basename "$file")

    # Get the lowercase extension.
    extension="${filename##*.}"
    extension=$(tr '[:upper:]' '[:lower:]' <<< ${extension})
    index=${indices[${counter}]}

    cp "${SOURCE}/${file}" "${TARGET}/${PREFIX}_${index}.${extension}"
    counter=$(( counter + 1 ))
done