How to use git pull without entering the passphrase

Question

I'm trying to pull from a GitHub repository in an unattended way, but everytime I do it I get:

Enter passphrase for key '/home/yc2/.ssh/id_rsa': 

And I have to enter it for it work. I managed to skip it by using

eval `ssh-agent`
ssh-add <I enter my passphrase>

But that's only maintained on the actual session, but I need to do it with a PHP script, but if it asks the password, the script doesn't works, so how can I make it to not ask the password?

Solution

You can use ssh-keygen -p to change the pass phrase on the key, including setting no pass phrase

ssh-keygen -p
Enter file in which the key is (/home/iain/.ssh/id_rsa): /home/iain/.ssh/tmp/id_rsa
Enter old passphrase: <existing pass phrase>
Key has comment '/home/iain/.ssh/tmp/id_rsa'
Enter new passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved with the new passphrase.

If you use this key for other things you may be safer generating a keypair just for your program to use.