git-commit-vandalism/Documentation/git-fsck-cache.txt
Linus Torvalds 6f97a894d6 Fix up git-fsck-cache documentation
Notably, the "--unreachable" flag no longer depends on specified heads,
and we should document what happens if no heads are given.
2005-05-22 14:32:26 -07:00

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git-fsck-cache(1)
=================
v0.1, May 2005
NAME
----
git-fsck-cache - Verifies the connectivity and validity of the objects in the database
SYNOPSIS
--------
'git-fsck-cache' [--tags] [--root] [--delta-depth] [--unreachable] [--cache] [<object>*]
DESCRIPTION
-----------
Verifies the connectivity and validity of the objects in the database.
OPTIONS
-------
<object>::
An object to treat as the head of an unreachability trace.
If no objects are given, git-fsck-cache defaults to using the
index file and all SHA1 references in .git/refs/* as heads.
--unreachable::
Print out objects that exist but that aren't readable from any
of the reference nodes.
--root::
Report root nodes.
--tags::
Report tags.
--cache::
Consider any object recorded in the cache also as a head node for
an unreachability trace.
--delta-depth::
Report back the length of the longest delta chain found.
It tests SHA1 and general object sanity, and it does full tracking of
the resulting reachability and everything else. It prints out any
corruption it finds (missing or bad objects), and if you use the
'--unreachable' flag it will also print out objects that exist but
that aren't readable from any of the specified head nodes.
So for example
git-fsck-cache --unreachable $(cat .git/HEAD)
or, for Cogito users:
git-fsck-cache --unreachable $(cat .git/refs/heads/*)
will do quite a _lot_ of verification on the tree. There are a few
extra validity tests to be added (make sure that tree objects are
sorted properly etc), but on the whole if "git-fsck-cache" is happy, you
do have a valid tree.
Any corrupt objects you will have to find in backups or other archives
(ie you can just remove them and do an "rsync" with some other site in
the hopes that somebody else has the object you have corrupted).
Of course, "valid tree" doesn't mean that it wasn't generated by some
evil person, and the end result might be crap. Git is a revision
tracking system, not a quality assurance system ;)
Extracted Diagnostics
---------------------
expect dangling commits - potential heads - due to lack of head information::
You haven't specified any nodes as heads so it won't be
possible to differentiate between un-parented commits and
root nodes.
missing sha1 directory '<dir>'::
The directory holding the sha1 objects is missing.
unreachable <type> <object>::
The <type> object <object>, isn't actually referred to directly
or indirectly in any of the trees or commits seen. This can
mean that there's another root node that you're not specifying
or that the tree is corrupt. If you haven't missed a root node
then you might as well delete unreachable nodes since they
can't be used.
missing <type> <object>::
The <type> object <object>, is referred to but isn't present in
the database.
dangling <type> <object>::
The <type> object <object>, is present in the database but never
'directly' used. A dangling commit could be a root node.
warning: git-fsck-cache: tree <tree> has full pathnames in it::
And it shouldn't...
sha1 mismatch <object>::
The database has an object who's sha1 doesn't match the
database value.
This indicates a serious data integrity problem.
(note: this error occured during early git development when
the database format changed.)
Environment Variables
---------------------
GIT_OBJECT_DIRECTORY::
used to specify the object database root (usually .git/objects)
GIT_INDEX_FILE::
used to specify the cache
Author
------
Written by Linus Torvalds <torvalds@osdl.org>
Documentation
--------------
Documentation by David Greaves, Junio C Hamano and the git-list <git@vger.kernel.org>.
GIT
---
Part of the link:git.html[git] suite