Terminal tab completion [duplicate]
Download bash_completion and source it from your .bashrc. Then put contrib/completion/git-completion.bash from the git distribution into bash_completion.d.
Alternatively you can install it via MacPorts.
For git there is an option available on compilation to support completion.
If you used port to install Git (which I recommend), you can reinstall git with this command
sudo port install git-core +svn+bash_completion+doc
Which will install git with bash completion, git-svn support and docs