You probably dont want to invoke this command yourself; it is started automatically when you use git-credential-cache(1).
This command listens on the Unix domain socket specified by <socket> for git-credential-cache clients. Clients may store and retrieve credentials. Each credential is held for a timeout specified by the client; once no credentials are held, the daemon exits.
If the --debug option is specified, the daemon does not close its stderr stream, and may output extra diagnostics to it even after it has begun listening for clients.