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GIT-UPDATE-REF(1) | Git Manual | GIT-UPDATE-REF(1) |
NAME¶
git-update-ref - Update the object name stored in a ref safelySYNOPSIS¶
git update-ref [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>] | --stdin [-z])
DESCRIPTION¶
Given two arguments, stores the <newvalue> in the <ref>, possibly dereferencing the symbolic refs. E.g. git update-ref HEAD <newvalue> updates the current branch head to the new object. Given three arguments, stores the <newvalue> in the <ref>, possibly dereferencing the symbolic refs, after verifying that 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>. 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 "ref:". More importantly, it allows the update of a ref file to follow these symbolic pointers, whether they are symlinks or these "regular file symbolic refs". It 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). If --no-deref is given, <ref> itself is overwritten, rather than the result of following the symbolic pointers. In general, usinggit update-ref HEAD "$head"
echo "$head" > "$GIT_DIR/HEAD"
update SP <ref> SP <newvalue> [SP <oldvalue>] LF create SP <ref> SP <newvalue> LF delete SP <ref> [SP <oldvalue>] LF verify SP <ref> [SP <oldvalue>] LF option SP <opt> LF
update SP <ref> NUL <newvalue> NUL [<oldvalue>] NUL create SP <ref> NUL <newvalue> NUL delete SP <ref> NUL [<oldvalue>] NUL verify SP <ref> NUL [<oldvalue>] NUL option SP <opt> NUL
Set <ref> to <newvalue> after verifying
<oldvalue>, if given. Specify a zero <newvalue> to ensure the ref
does not exist after the update and/or a zero <oldvalue> to make sure
the ref does not exist before the update.
create
Create <ref> with <newvalue> after verifying
it does not exist. The given <newvalue> may not be zero.
delete
Delete <ref> after verifying it exists with
<oldvalue>, if given. If given, <oldvalue> may not be zero.
verify
Verify <ref> against <oldvalue> but do not
change it. If <oldvalue> zero or missing, the ref must not exist.
option
Modify behavior of the next command naming a <ref>.
The only valid option is no-deref to avoid dereferencing a symbolic ref.
If all <ref>s can be locked with matching <oldvalue>s
simultaneously, all modifications are performed. Otherwise, no modifications
are performed. Note that while each individual <ref> is updated or
deleted atomically, a concurrent reader may still see a subset of the
modifications.
LOGGING UPDATES¶
If config parameter "core.logAllRefUpdates" is true and the ref is one under "refs/heads/", "refs/remotes/", "refs/notes/", or the symbolic ref HEAD; or the file "$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: 1.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 <newvalue> and "committer" is the committer’s
name, email address and date in the standard Git committer ident format.
Optionally with -m:
1.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.
GIT¶
Part of the git(1) suite05/28/2018 | Git 2.1.4 |