how-to get commit content with pre-receive hook ?

Hello the list,

Until now I ever had a quite "basic" Git usage, but now I'm working on a project based on Git hooks feature.. and I'm a very beginner with Git hooks !

My need consist doing a syntax check on submitted files before a 'git push'. So the right hook is 'pre-receive' and I'm already able to identify the files I want to check using 'git show'.

But I don't know how to get the *content* of the file being submitted to run my syntax check rules against it !

I googled but most examples using pre-receive I found are doing sanity check on enveloppe but never on actual content of the file !

Could someone here put me on the rails ?

Regards,