Nemo action: Git diff with Meld

nemo-action-git-diff-meld.md

Nemo action: Git diff with Meld

Right-click any file, folder, or the background of a Nemo window inside a git repository to open a diff in Meld.

• Right-click a file - diff that file
• Right-click a folder icon - diff the contents of that folder
• Right-click the empty area of a Nemo window - diff the contents of the current directory

If the file or directory has no changes, a popup tells you so. If the path is not inside a git repository, an error popup is shown. Both popups appear in front of the Nemo window.

Requirements

• Meld
• xdotool (used to bring the popup in front of Nemo)
• zenity (usually installed by default on GNOME/Cinnamon)
• git

On Debian/Ubuntu/Mint:

sudo apt install meld xdotool zenity

Installation

1. Create the actions directory if it doesn't exist:

mkdir -p ~/.local/share/nemo/actions

2. Copy the script and make it executable:

cp git-meld-diff.sh ~/.local/share/nemo/actions/
chmod +x ~/.local/share/nemo/actions/git-meld-diff.sh

3. Copy the three action files:

cp git-meld-diff-file.nemo_action ~/.local/share/nemo/actions/
cp git-meld-diff-dir.nemo_action  ~/.local/share/nemo/actions/
cp git-meld-diff-bg.nemo_action   ~/.local/share/nemo/actions/

4. Edit the three .nemo_action files:

Replace /home/ozh/ with your own home directory path (full path, not ~/you).

5. Restart Nemo:

nemo -q ; sleep 1 ; nemo &

Files

git-meld-diff.sh

The script shared by all three actions. Handles file, directory, and background cases.

#!/bin/bash
# Open Meld to show git diff for a file or directory

TARGET="${1#file://}"

WINDOWID=$(xdotool getactivewindow 2>/dev/null)

zenity_msg() {
    local type="$1"
    local msg="$2"
    if [ -n "$WINDOWID" ]; then
        zenity --"$type" --text="$msg" --attach="$WINDOWID" 2>/dev/null
    else
        zenity --"$type" --text="$msg" 2>/dev/null
    fi
}

if [ -f "$TARGET" ]; then
    DIR=$(dirname "$TARGET")
else
    DIR="$TARGET"
fi

GIT_ROOT=$(git -C "$DIR" rev-parse --show-toplevel 2>/dev/null)

if [ -z "$GIT_ROOT" ]; then
    zenity_msg "error" "Not a git repository."
    exit 1
fi

if [ -f "$TARGET" ]; then
    # Single file: diff that file
    if git -C "$GIT_ROOT" diff --quiet -- "$TARGET" && \
       git -C "$GIT_ROOT" diff --quiet --cached -- "$TARGET"; then
        zenity_msg "info" "No changes in this file."
        exit 0
    fi
    meld "$TARGET" &
else
    # Directory: diff scoped to that directory
    if git -C "$GIT_ROOT" diff --quiet -- "$DIR" && \
       git -C "$GIT_ROOT" diff --quiet --cached -- "$DIR"; then
        zenity_msg "info" "No changes in this directory."
        exit 0
    fi
    meld "$DIR" &
fi

git-meld-diff-file.nemo_action

Appears when right-clicking a file.

[Nemo Action]
Name=Git diff with Meld
Comment=Show uncommitted changes in Meld
Exec=/home/ozh/.local/share/nemo/actions/git-meld-diff.sh %F
Icon-Name=meld
Selection=S
Mimetypes=text/plain;text/html;text/css;text/xml;text/x-script.python;text/x-php;text/x-shellscript;text/x-markdown;application/javascript;application/json;application/xml;application/x-php;application/x-shellscript;

git-meld-diff-dir.nemo_action

Appears when right-clicking a folder icon.

[Nemo Action]
Name=Git diff with Meld
Comment=Show uncommitted changes in Meld
Exec=/home/ozh/.local/share/nemo/actions/git-meld-diff.sh %F
Icon-Name=meld
Selection=S
Mimetypes=inode/directory;

git-meld-diff-bg.nemo_action

Appears when right-clicking the empty background of a Nemo window.

[Nemo Action]
Name=Git diff with Meld
Comment=Show uncommitted changes in Meld
Exec=/home/ozh/.local/share/nemo/actions/git-meld-diff.sh %P
Icon-Name=meld
Selection=None
Extensions=any;

Notes

• The Mimetypes list in the file action covers common dev file types. If a file type you use is missing from the right-click menu, check its mimetype with file --mime-type yourfile and add it to git-meld-diff-file.nemo_action.
• For directory and background actions, Meld is scoped to the target directory, not the git root, so you only see changes relevant to where you clicked.
• xdotool captures the active window ID at script start so the popup attaches to Nemo even after focus changes.