Setting up visual diff and merge for Git on OSX

They are mentions around the web about the best visual diff and merge tools to use for Git on OSX - for example this question on StackOverflow.

However I decided to go with the suggestion inside of Pro Git. The following is a summary of what I did, extracted more or less from the book.

#!/bin/sh

# This script is a summary of the advice provided by the book Pro Git (Thanks to author).
# to create visual merge and diff scripts to be used from cmd line git
# Script by Peter Lynch (http://blog.peterlynch.ca)

# 1. Download p4merge from perforce
# http://www.perforce.com/perforce/downloads/macintoshlist.html#macosx104u ( summary )
# Download the "P4V: Visual Client", mount the the DMG, copy p4merge to /Applications

# 2. Create wrapper scripts
sudo cat > /usr/local/bin/extMerge <<extMerge
#!/bin/sh
/Application/p4merge.app/Contents/MacOS/p4merge \$* 
extMerge
sudo cat > /usr/local/bin/extDiff <<extDiff
#!/bin/sh
[ \$# -eq 7 ] && /usr/local/bin/extMerge "\$2" "\$5" 
extDiff

# 3. Set owner and perms
sudo chown root /usr/local/bin/extMerge
sudo chown root /usr/local/bin/extDiff
sudo chmod ugo+x /usr/local/bin/extMerge
sudo chmod ugo+x /usr/local/bin/extDiff

# 4. Configure Git to use our new scripts
git config --global merge.tool extMerge
git config --global mergetool.extMerge.cmd \
    'extMerge "$BASE" "$LOCAL" "$REMOTE" "$MERGED"'
git config --global mergetool.trustExitCode false
git config --global diff.external extDiff

# 5. confirm
git config -l
echo ----------
ls -la /usr/local/bin/ext*

Remember to execute the script using sudo or else you'll get permission denied errors.

Also, to bypass the external diff don't forget you can use

git diff --no-ext-diff

.