SYNOPSIS
--------
-'git update-ref' [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>])
+[verse]
+'git update-ref' [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>] | --stdin [-z])
DESCRIPTION
-----------
With `-d` flag, it deletes the named <ref> after verifying it
still contains <oldvalue>.
+With `--stdin`, update-ref reads instructions from standard input and
+performs all modifications together. Specify commands of the form:
+
+ update SP <ref> SP <newvalue> [SP <oldvalue>] LF
+ create SP <ref> SP <newvalue> LF
+ delete SP <ref> [SP <oldvalue>] LF
+ verify SP <ref> [SP <oldvalue>] LF
+ option SP <opt> LF
+
+Quote fields containing whitespace as if they were strings in C source
+code. Alternatively, use `-z` to specify commands without quoting:
+
+ update SP <ref> NUL <newvalue> NUL [<oldvalue>] NUL
+ create SP <ref> NUL <newvalue> NUL
+ delete SP <ref> NUL [<oldvalue>] NUL
+ verify SP <ref> NUL [<oldvalue>] NUL
+ option SP <opt> NUL
+
+Lines of any other format or a repeated <ref> produce an error.
+Command meanings are:
+
+update::
+ Set <ref> to <newvalue> after verifying <oldvalue>, if given.
+ Specify a zero <newvalue> to ensure the ref does not exist
+ after the update and/or a zero <oldvalue> to make sure the
+ ref does not exist before the update.
+
+create::
+ Create <ref> with <newvalue> after verifying it does not
+ exist. The given <newvalue> may not be zero.
+
+delete::
+ Delete <ref> after verifying it exists with <oldvalue>, if
+ given. If given, <oldvalue> may not be zero.
+
+verify::
+ Verify <ref> against <oldvalue> but do not change it. If
+ <oldvalue> zero or missing, the ref must not exist.
+
+option::
+ Modify behavior of the next command naming a <ref>.
+ The only valid option is `no-deref` to avoid dereferencing
+ a symbolic ref.
+
+Use 40 "0" or the empty string to specify a zero value, except that
+with `-z` an empty <oldvalue> is considered missing.
+
+If all <ref>s can be locked with matching <oldvalue>s
+simultaneously, all modifications are performed. Otherwise, no
+modifications are performed. Note that while each individual
+<ref> is updated or deleted atomically, a concurrent reader may
+still see a subset of the modifications.
Logging Updates
---------------
-If config parameter "core.logAllRefUpdates" is true or the file
-"$GIT_DIR/logs/<ref>" exists then `git update-ref` will append
+If config parameter "core.logAllRefUpdates" is true and the ref is one under
+"refs/heads/", "refs/remotes/", "refs/notes/", or the symbolic ref HEAD; or
+the file "$GIT_DIR/logs/<ref>" exists then `git update-ref` will append
a line to the log file "$GIT_DIR/logs/<ref>" (dereferencing all
symbolic refs before creating the log name) describing the change
in ref value. Log lines are formatted as:
Where "oldsha1" is the 40 character hexadecimal value previously
stored in <ref>, "newsha1" is the 40 character hexadecimal value of
<newvalue> and "committer" is the committer's name, email address
-and date in the standard GIT committer ident format.
+and date in the standard Git committer ident format.
Optionally with -m: