|
HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|
|
NAME | SYNOPSIS | DESCRIPTION | LOGGING UPDATES | NOTES | SEE ALSO | GIT | COLOPHON |
|
|
|
GIT-UPDATE-REF(1) Git Manual GIT-UPDATE-REF(1)
git-update-ref - Update the object name stored in a ref safely
git update-ref [-m <reason>] [--no-deref] -d <ref> [<old-oid>]
git update-ref [-m <reason>] [--no-deref] [--create-reflog] <ref> <new-oid> [<old-oid>]
git update-ref [-m <reason>] [--no-deref] --stdin [-z] [--batch-updates]
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.
With --batch-updates, update-ref executes the updates in a batch
but allows individual updates to fail due to invalid or incorrect
user input, applying only the successful updates. However,
system-related errors—such as I/O failures or memory issues—will
result in a full failure of all batched updates. Any failed
updates will be reported in the following format:
rejected SP (<old-oid> | <old-target>) SP (<new-oid> | <new-target>) SP <rejection-reason> LF
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 that it does not
exist. The given <new-oid> may not be zero.
delete
Delete <ref> after verifying that 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 that it does not exist.
symref-delete
Delete <ref> after verifying that 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.
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.
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).
git-symbolic-ref(1)
Part of the git(1) suite
This page is part of the git (Git distributed version control
system) project. Information about the project can be found at
⟨http://git-scm.com/⟩. If you have a bug report for this manual
page, see ⟨http://git-scm.com/community⟩. This page was obtained
from the project's upstream Git repository
⟨https://github.com/git/git.git⟩ on 2025-08-11. (At that time,
the date of the most recent commit that was found in the
repository was 2025-08-07.) If you discover any rendering
problems in this HTML version of the page, or you believe there is
a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
[email protected]
Git 2.51.0.rc1 2025-08-07 GIT-UPDATE-REF(1)
Pages that refer to this page: git(1), git-merge-tree(1), git-show-ref(1), git-symbolic-ref(1), git-worktree(1), gitrepository-layout(5), gitglossary(7)
|
HTML rendering created 2025-09-06 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH. |
|