How to Compare Two Directories With diff and Meld

Updated: 28 September 2026 · Applies to: GNU diffutils 3.7 and later and Meld 3.22 on AlmaLinux and Rocky Linux 9 and 10, Ubuntu 24.04 and 26.04, Debian 13, Fedora 44

To see how two folders differ, for example a backup and the live site, or two releases of an application, use diff on the command line or Meld on a desktop. diff is installed on every Linux server; Meld needs a graphical desktop. We tested the commands below on AlmaLinux 10 and Debian 13.

1. Which files differ (diff)

diff -rq /var/www/site /root/backup/site

-r compares all subfolders and -q only names the files instead of printing every changed line. The output looks like this:

Files /var/www/site/config.php and /root/backup/site/config.php differ
Only in /var/www/site/uploads: new-image.jpg
Only in /root/backup/site: old-plugin

2. What changed inside the files

diff -ru /root/backup/site /var/www/site > site-changes.diff

-u gives the unified format: lines starting with - were removed, lines starting with + were added, with three lines of context around each change. Open the result with less site-changes.diff.

Useful options

• -N: also show the full content of files that exist on only one side.
• --exclude=cache or -x '*.log': skip folders or files that always differ. Repeat for several patterns.
• -w: ignore changes in spaces and tabs; -B: ignore blank lines.
• --color=auto: colour the output in the terminal.

Quick check without reading the content

To know only whether anything changed, compare checksums. This is also useful across two servers:

cd /var/www/site && find . -type f -exec sha256sum {} + | sort -k 2 > /tmp/live.sha
cd /root/backup/site && find . -type f -exec sha256sum {} + | sort -k 2 > /tmp/backup.sha
diff /tmp/backup.sha /tmp/live.sha

For a dry run of what rsync would copy, rsync -rcn --delete --itemize-changes /root/backup/site/ /var/www/site/ lists the differences without changing anything. Keep the -n: without it, rsync would make the live folder match the backup and delete the extra files.

3. Meld: compare folders side by side

Meld is a graphical compare and merge tool for Linux desktops. Install it:

apt install meld                               # Ubuntu, Debian
dnf install meld                               # Fedora
dnf install epel-release && dnf install meld   # AlmaLinux, Rocky Linux (from EPEL)

Start it with two (or three) folders:

meld /root/backup/site /var/www/site

Meld shows both trees next to each other and marks new, missing and changed files in colour. Double-click a file to see its changes line by line and copy changes from one side to the other with the arrows. To compare folders on a remote server, copy them to your computer first, or mount the server's folder with sshfs.

Official documentation: GNU diffutils manual and Meld.