NAME
----
-git-update-ref - update the object name stored in a ref safely
+git-update-ref - Update the object name stored in a ref safely
SYNOPSIS
--------
-'git-update-ref' <ref> <newvalue> [<oldvalue>] [-m <reason>]
+'git-update-ref' [-m <reason>] (-d <ref> <oldvalue> | [--no-deref] <ref> <newvalue> [<oldvalue>])
DESCRIPTION
-----------
the current value of the <ref> matches <oldvalue>.
E.g. `git-update-ref refs/heads/master <newvalue> <oldvalue>`
updates the master branch head to <newvalue> only if its current
-value is <oldvalue>.
+value is <oldvalue>. You can specify 40 "0" or an empty string
+as <oldvalue> to make sure that the ref you are creating does
+not exist.
It also allows a "ref" file to be a symbolic pointer to another
ref file by starting with the four-byte header sequence of
filesystem to follow them, but will overwrite such a symlink to
somewhere else with a regular filename).
+If --no-deref is given, <ref> itself is overwritten, rather than
+the result of following the symbolic pointers.
+
In general, using
git-update-ref HEAD "$head"
ref symlink to some other tree, if you have copied a whole
archive by creating a symlink tree).
+With `-d` flag, it deletes the named <ref> after verifying it
+still contains <oldvalue>.
+
+
Logging Updates
---------------
If config parameter "core.logAllRefUpdates" is true or the file