Filemerge with git - It's all gone horribly wrong

Following this tutorial to the letter, whenever I now run a diff, I get the following:

~~$ git diff
fatal: cannot exec '/Users/john/git-diff-cmd.sh': Permission denied
external diff died, stopping at footer.php.

This is obviously undesirable!! How can I fix it, and how can I get File开发者_如何学Cmerge and GIT to play nice?

your script has to be executable:

chmod u+x '/Users/john/git-diff-cmd.sh'

It looks like you don't have execution privileges for your script file. Go to the terminal and type

chmod a+x /Users/john/git-diff-cmd.sh

and then try running git again.