prefix filename with file's date

rename-idate.sh

#!/bin/bash
# Indicated files will be renamed by prefixing with their modification date.
# Useful for photos from old devices that did not store metadata.

# This only prints the `mv` commands (preview); pipe it to `sh` to apply the changes

function filetime() {
	local f=$1
	local t=$(stat -c %y "$f")
	t=${t%% *}
	echo ${t//-/}
}

for i in "$@"; do
	i2="$(filetime $i)-$i"
	echo "mv $i $i2"
done