I can't make git diff use opendiff

I want to use opendiff as default diff-tool for git diff. This used to work but for some reason stopped working. I'm using a script:

echo opendiff $2 $5 > opendiff-git.sh

which is set in .gitconfig:

[diff]
external = ~/opendiff-git.sh

This stopped working for me lately. What is wrong?

Update: When I cloned a new repository everything worked fine! Strange!

I found this question while I was trying to set opendiff as my git diff & merge tool. Weird thing is that when I used the echo opendiff $2 $5 > opendiff-git.sh to create a script the script did not contain the argument place holders $2 $5 I added them in manually and it started working!

This command

echo opendiff $2 $5 > opendiff-git.sh

Resulted in opendiff-git.sh file containing

opendiff

I added the two argument placeholders $2 $5 manually

opendiff $2 $5

Made the shell script executable as suggested by knittl

chmod +x ~/opendiff-git.sh

And it works!

make sure your opendiff-git.sh file has its executable bits set:

chmod +x ~/opendiff-git.sh

You can now specify a default tool using git config. To use FileMerge, i.e. opendiff, run:

git config --global diff.tool opendiff

If you view your ~/.gitconfig file, you should now see:

[diff]
    tool = opendiff

It should now work.