git-update-ref (1)

Name

git-update-ref - Update the object name stored in a ref safely

Synopsis

git update-ref [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>])

Description

Git Manual                                      GIT-UPDATE-REF(1)



NAME
     git-update-ref - Update the object name stored in a ref
     safely

SYNOPSIS
     git update-ref [-m <reason>] (-d <ref> [<oldvalue>] | [--no-deref] <ref> <newvalue> [<oldvalue>])


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, using

         git update-ref HEAD "$head"

     should be a lot safer than doing

         echo "$head" > "$GIT_DIR/HEAD"

     both from a symlink following standpoint and an error
     checking standpoint. The "refs/" rule for symlinks means
     that symlinks that point to "outside" the tree are safe:
     they'll be followed for reading but not for writing (so
     we'll never write through a ref symlink to some other tree,
     if you have copied a whole archive by creating a symlink



Git 1.7.9.2          Last change: 02/22/2012                    1






Git Manual                                      GIT-UPDATE-REF(1)



     tree).

     With -d flag, it deletes the named <ref> after verifying it
     still contains <oldvalue>.

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) suite



ATTRIBUTES
     See attributes(5) for descriptions of the following
     attributes:

     +---------------+--------------------------+
     |ATTRIBUTE TYPE |     ATTRIBUTE VALUE      |
     +---------------+--------------------------+
     |Availability   | developer/versioning/git |
     +---------------+--------------------------+
     |Stability      | Uncommitted              |
     +---------------+--------------------------+
NOTES
     This software was built from source available at



Git 1.7.9.2          Last change: 02/22/2012                    2






Git Manual                                      GIT-UPDATE-REF(1)



     https://java.net/projects/solaris-userland.  The original
     community source was downloaded from  http://git-
     core.googlecode.com/files/git-1.7.9.2.tar.gz

     Further information about this software can be found on the
     open source community website at http://git-scm.com/.

















































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