Git diffs in your favourite diff tool

git-diff.sh

#!/bin/sh

function print_example() {
    echo "Example"
    echo "  git-diff develop master"
}

function print_usage() {
    echo "Usage"
    echo "  git-diff <branch|tag|commit> <branch|tag|commit>"
    echo "  OR"
    echo "  git-diff --cached"
}

if [ "$1" = "--help" ] || [ "$1" = "-h" ] ; then
    print_usage
    exit 0
fi

FROM="$1"
FROM_DESC="$FROM"
TO="$2"
TO_DESC="$TO"

if [ "$1" = "--cached" ] || [ "$1" = "-c" ] ; then
    FROM=""
    FROM_DESC="staged"
    TO="HEAD"
    TO_DESC="working dir"
elif [ -z "$FROM" ] || [ -z "$TO" ]; then
    echo "Error: missing arguments"
    echo ""
    print_usage
    echo ""
    print_example
    exit 1
fi

if ! [ -d .git ]; then # .git folder exists?
    echo "Error: current directory is not a git root directory"
    exit 1
fi

DIR=${TMPDIR%/}/gitdiff # `%/` removes trailing slash
rm -rf "$DIR"
for i in $(git diff --name-only $FROM $TO) ; do
    # Setup folder structure
    mkdir -p $DIR/"$FROM_DESC"/"$(dirname $i)";
    mkdir -p $DIR/"$TO_DESC"/"$(dirname $i)";
    
    # Get revision of files
    git show "$FROM":"$i" > "$DIR"/"$FROM_DESC"/$i;
    git show "$TO":"$i" > "$DIR"/"$TO_DESC"/$i;
done

# Use git's difftool or opendiff as alternative
DIFFTOOL=$(expr "$(git config --get diff.tool)" '|' "opendiff")

$($DIFFTOOL "$DIR"/"$FROM_DESC" "$DIR"/"$TO_DESC")

Examples

• Branches diff git-diff master develop
• Tags diff git-diff 1.0.0 1.0.1
• Commits diff git-diff 089fe25 0357e69
• Mixed diff git-diff 1.0.1 develop
• Staged diff git-diff --cached