git-fsck-objects.txt

git-fsck-objects(1)
===================

NAME
----
git-fsck-objects - Verifies the connectivity and validity of the objects in the database


SYNOPSIS
--------
[verse]
'git-fsck-objects' [--tags] [--root] [--unreachable] [--cache]
 [--standalone | --full] [--strict] [<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-objects 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 index also as a head node for
an unreachability trace.

--standalone::
Limit checks to the contents of GIT_OBJECT_DIRECTORY
($GIT_DIR/objects), making sure that it is consistent and
complete without referring to objects found in alternate
object pools listed in GIT_ALTERNATE_OBJECT_DIRECTORIES,
nor packed git archives found in $GIT_DIR/objects/pack;
cannot be used with --full.

--full::
Check not just objects in GIT_OBJECT_DIRECTORY
($GIT_DIR/objects), but also the ones found in alternate
object pools listed in GIT_ALTERNATE_OBJECT_DIRECTORIES,
and in packed git archives found in $GIT_DIR/objects/pack
and corresponding pack subdirectories in alternate
object pools; cannot be used with --standalone.

--strict::
Enable more strict checking, namely to catch a file mode
recorded with g+w bit set, which was created by older
versions of git. Existing repositories, including the
Linux kernel, git itself, and sparse repository have old
objects that triggers this check, but it is recommended
to check new projects with this flag.

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-objects --unreachable HEAD $(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-objects" 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-objects: 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.

Environment Variables
---------------------

GIT_OBJECT_DIRECTORY::
used to specify the object database root (usually $GIT_DIR/objects)

GIT_INDEX_FILE::
used to specify the index file of the index

GIT_ALTERNATE_OBJECT_DIRECTORIES::
used to specify additional object database roots (usually unset)

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 gitlink:git[7] suite