SYNOPSIS
git update-ref [-m <reason>] [--no-deref] (-d <ref> [<old-oid>] | [--create-reflog] <ref> <new-oid> [<old-oid>] | --stdin [-z])
DESCRIPTION
Given two arguments, stores the <new-oid> in the <ref>, possibly
dereferencing the symbolic refs. E.g. git
update-ref
HEAD
<new-oid> updates the current branch head to the new object.
Given three arguments, stores the <new-oid> in the <ref>,
possibly dereferencing the symbolic refs, after verifying that
the current value of the <ref> matches <old-oid>.
E.g. git
update-ref
refs/heads/master
<new-oid> <old-oid>
updates the master branch head to <new-oid> only if its current
value is <old-oid>. You can specify 40 "0" or an empty string
as <old-oid> to make sure that the ref you are creating does
not exist.
The final arguments are object names; this command without any options
does not support updating a symbolic ref to point to another ref (see
git-symbolic-ref(1)). But git
update-ref
--stdin
does have
the symref-
* commands so that regular refs and symbolic refs can be
committed in the same transaction.
If --no-deref is given, <ref> itself is overwritten, rather than the result of following the symbolic pointers.
With -d
, it deletes the named <ref> after verifying that it
still contains <old-oid>.
With --stdin
, update-ref reads instructions from standard input and
performs all modifications together. Specify commands of the form:
update SP <ref> SP <new-oid> [SP <old-oid>] LF create SP <ref> SP <new-oid> LF delete SP <ref> [SP <old-oid>] LF verify SP <ref> [SP <old-oid>] LF symref-update SP <ref> SP <new-target> [SP (ref SP <old-target> | oid SP <old-oid>)] LF symref-create SP <ref> SP <new-target> LF symref-delete SP <ref> [SP <old-target>] LF symref-verify SP <ref> [SP <old-target>] LF option SP <opt> LF start LF prepare LF commit LF abort LF
With --create-reflog
, update-ref will create a reflog for each ref
even if one would not ordinarily be created.
Quote fields containing whitespace as if they were strings in C source code; i.e., surrounded by double-quotes and with backslash escapes. Use 40 "0" characters or the empty string to specify a zero value. To specify a missing value, omit the value and its preceding SP entirely.
Alternatively, use -z
to specify in NUL-terminated format, without
quoting:
update SP <ref> NUL <new-oid> NUL [<old-oid>] NUL create SP <ref> NUL <new-oid> NUL delete SP <ref> NUL [<old-oid>] NUL verify SP <ref> NUL [<old-oid>] NUL symref-update SP <ref> NUL <new-target> [NUL (ref NUL <old-target> | oid NUL <old-oid>)] NUL symref-create SP <ref> NUL <new-target> NUL symref-delete SP <ref> [NUL <old-target>] NUL symref-verify SP <ref> [NUL <old-target>] NUL option SP <opt> NUL start NUL prepare NUL commit NUL abort NUL
In this format, use 40 "0" to specify a zero value, and use the empty string to specify a missing value.
In either format, values can be specified in any form that Git recognizes as an object name. Commands in any other format or a repeated <ref> produce an error. Command meanings are:
- update
-
Set <ref> to <new-oid> after verifying <old-oid>, if given. Specify a zero <new-oid> to ensure the ref does not exist after the update and/or a zero <old-oid> to make sure the ref does not exist before the update.
- create
-
Create <ref> with <new-oid> after verifying it does not exist. The given <new-oid> may not be zero.
- delete
-
Delete <ref> after verifying it exists with <old-oid>, if given. If given, <old-oid> may not be zero.
- symref-update
-
Set <ref> to <new-target> after verifying <old-target> or <old-oid>, if given. Specify a zero <old-oid> to ensure that the ref does not exist before the update.
- verify
-
Verify <ref> against <old-oid> but do not change it. If <old-oid> is zero or missing, the ref must not exist.
symref-create: Create symbolic ref <ref> with <new-target> after verifying it does not exist.
- symref-delete
-
Delete <ref> after verifying it exists with <old-target>, if given.
- symref-verify
-
Verify symbolic <ref> against <old-target> but do not change it. If <old-target> is missing, the ref must not exist. Can only be used in
no-deref
mode. - option
-
Modify the behavior of the next command naming a <ref>. The only valid option is
no-deref
to avoid dereferencing a symbolic ref. - start
-
Start a transaction. In contrast to a non-transactional session, a transaction will automatically abort if the session ends without an explicit commit. This command may create a new empty transaction when the current one has been committed or aborted already.
- prepare
-
Prepare to commit the transaction. This will create lock files for all queued reference updates. If one reference could not be locked, the transaction will be aborted.
- commit
-
Commit all reference updates queued for the transaction, ending the transaction.
- abort
-
Abort the transaction, releasing all locks if the transaction is in prepared state.
If all <ref>s can be locked with matching <old-oid>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 and the ref is one
under "refs/heads/", "refs/remotes/", "refs/notes/", or a pseudoref
like HEAD or ORIG_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:
oldsha1 SP newsha1 SP committer LF
Where "oldsha1" is the 40 character hexadecimal value previously stored in <ref>, "newsha1" is the 40 character hexadecimal value of <new-oid> and "committer" is the committer’s name, email address and date in the standard Git committer ident format.
Optionally with -m:
oldsha1 SP newsha1 SP committer TAB message LF
Where all fields are as described above and "message" is the value supplied to the -m option.
An update will fail (without changing <ref>) if the current user is unable to create a new log file, append to the existing log file or does not have committer information available.
NOTES
Symbolic refs were initially implemented using symbolic links. This is now deprecated since not all filesystems support symbolic links.
This command follows real symlinks only if they start with "refs/": otherwise it will just try to read them and update them as a regular file (i.e. it will allow the filesystem to follow them, but will overwrite such a symlink to somewhere else with a regular filename).
SEE ALSO
GIT
Part of the git(1) suite