I need to install git on a server that will be shared and accessed by multiple users.
I assume I will use git+ssh, so each user will have a system account, but how do I go about install git and a repository so that each user can push/pull over a local IP?
gitosis may make things easier for you.
Installing Gitosis is described in the Ubuntu Wiki:
https://help.ubuntu.com/community/Git#Setting%20up%20Git%20and%20Project%20Management
Gitosis is a widely used git server. The advantage with it is, that the settings are a git repository. After the initial setup, you can just change settings, push them and they'll automatically be applied.
Normally, you just need to set each user's umask to 0002, add create various groups for them to work together in (e.g.
sudo addgroup some-project; sudo adduser USER some-project
) and create a directory for them to collaborate in (e.g.sudo mkdir -p /srv/git/some-project
) and then make the directory writable (and setgid) for the group (e.g.sudo chown root:coders /srv/git/some-project; sudo chmod g+ws /srv/git/some-project
)