I wrote a script to find the files which are not present between two folders. Initially I used diff which works fine for source codes but when I want to just check for folders and files newly added to a directory without having to compare its content, diff is very slow. I wrote it mainly for backup purposes. For example, I have documents written to optical disk for archiving. I want to know which are the newly added files since the archival. So I can quickly compare the folder from optical disk and the hard drive to get a list of file I need to backup. Checking content takes ages.

#!/bin/bash

if [ $# -ne 2 ]; then
    echo "Usage: $0 <folder1> <folder2>"
    exit 1
fi

folder1_path="$1"
folder2_path="$2"

# List all files in first folder
find "$folder1_path" -type f | sed "s#${folder1_path}/##" | sort > files_in_folder1.txt

# List all files in second folder
find "$folder2_path" -type f | sed "s#${folder2_path}/##" | sort > files_in_folder2.txt

echo 'Files in folder1 that are not in folder2:'
comm -23 files_in_folder1.txt files_in_folder2.txt

echo ''
echo 'Files in folder2 that are not in folder1:'
comm -23 files_in_folder2.txt files_in_folder1.txt

# Clean up
rm files_in_folder1.txt files_in_folder2.txt

Script for checking content difference using diff

#!/bin/bash

# find difference between file and folder contents

diff -rq "$1" "$2"