mirror of
https://github.com/git/git
synced 2024-10-30 04:01:21 +00:00
59 lines
1.8 KiB
Text
59 lines
1.8 KiB
Text
|
git-update-ref(1)
|
||
|
|
=================
|
||
|
|
|
||
|
|
NAME
|
||
|
|
----
|
||
|
|
git-update-ref - update the object name stored in a ref safely
|
||
|
|
|
||
|
|
SYNOPSIS
|
||
|
|
--------
|
||
|
|
`git-update-ref` <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>.
|
||
|
|
|
||
|
|
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).
|
||
|
|
|
||
|
|
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).
|
||
|
|
|
||
|
|
Author
|
||
|
|
------
|
||
|
|
Written by Linus Torvalds <torvalds@osdl.org>.
|
||
|
|
|
||
|
|
GIT
|
||
|
|
---
|
||
|
|
Part of the gitlink:git[7] suite
|