Bash script to keep the lightest version of duplicate audio or video files that have been compressed and share a common filename beginning.

delete-largest-duplicate.sh

#!/usr/bin/env bash

# This script looks for near duplicates in the current directory and keeps only the one with the smallest filesize.
# By that I mean that a file and its duplicate have the same name beginning up to a certain character position
# (i.e: a title) with an additionnal variable part at the end (i.e: a timestamp).
#
# The duplicates contain the "same" information for a human, but are actually encoded differently. Hence they can't 
# be compared using a hash. For instance video files encoded differently, or a raw music file and its compressed mp3
# counterpart.
# The heaviest file is moved to an archive directory to review before deleting
#
# This script is courtesy of u/Mount_Gamer on reddit where he helped me solve this problem
# src: https://www.reddit.com/r/bash/comments/y70r7j/comment/istxaj2/?utm_source=share&utm_medium=web2x&context=3

archive_dir="./archive-dir/"    # Dir to store the heavier duplicate instead of deleting them immediately
num_common_chars=14             # Number of characters common for the shortest filename in the directory

for i in *
do
	for z in *
	do
		if [[ "${i:0:num_common_chars}" == "${z:0:num_common_chars}" ]] && [[ "$i" != "$z" ]]
		then
			outerloop=$(du -m "$i" | awk '{print $1}')
			innerloop=$(du -m "$z" | awk '{print $1}')

			if (( innerloop < outerloop ))
			then
				mv "$i" "$archive_dir"
			else
				mv "$z" "$archive_dir"
			fi
		fi
	done
done