I've had a look at all similar questions however. However, I've double checked and something strange is definitely happening.
On one server (Solaris with gitGit 1.8.1) I cloned the gitGit repository then copied the .git folder into my existing live files. This worked perfectly, I could run
git status then
git diff [filename] to check any files that were different.
On another server (Solaris with gitGit 1.7.6) I'm doing exactly the same however
git diff [filename] shows nothing, even if the contents of the file is definitely different. I have also tested adding a new file, committing it, and then editing. SameThe same issue, git status shows the file as changed, but git diff shows nothing. If I download the changed file and run a diff locally then I get diff output.