git-commit-vandalism/Documentation/git-update-ref.txt
Martin von Zweigbergk 7791a1d9b9 Documentation: use [verse] for SYNOPSIS sections
The SYNOPSIS sections of most commands that span several lines already
use [verse] to retain line breaks. Most commands that don't span
several lines seem not to use [verse]. In the HTML output, [verse]
does not only preserve line breaks, but also makes the section
indented, which causes a slight inconsistency between commands that
use [verse] and those that don't. Use [verse] in all SYNOPSIS sections
for consistency.

Also remove the blank lines from git-fetch.txt and git-rebase.txt to
align with the other man pages. In the case of git-rebase.txt, which
already uses [verse], the blank line makes the [verse] not apply to
the last line, so removing the blank line also makes the formatting
within the document more consistent.

While at it, add single quotes to 'git cvsimport' for consistency with
other commands.

Signed-off-by: Martin von Zweigbergk <martin.von.zweigbergk@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2011-07-06 14:26:26 -07:00

91 lines
3.1 KiB
Plaintext

git-update-ref(1)
=================
NAME
----
git-update-ref - Update the object name stored in a ref safely
SYNOPSIS
--------
[verse]
'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" > "$GIT_DIR/HEAD"
both from a symlink following standpoint *and* an error checking
standpoint. The "refs/" rule for symlinks means that symlinks
that point to "outside" the tree are safe: they'll be followed
for reading but not for writing (so we'll never write through a
ref symlink to some other tree, if you have copied a whole
archive by creating a symlink tree).
With `-d` flag, it deletes the named <ref> after verifying it
still contains <oldvalue>.
Logging Updates
---------------
If config parameter "core.logAllRefUpdates" is true or the file
"$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
<newvalue> 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.
GIT
---
Part of the linkgit:git[1] suite