$GIT_DIR (e.g. "HEAD", "refs/heads/master"). When
unspecified, update from all heads the remote side has.
-
-Author
-------
-Written by Linus Torvalds <torvalds@osdl.org>
-
-Documentation
---------------
-Documentation by Junio C Hamano.
-
GIT
---
Part of the linkgit:git[1] suite