git-fsck-cache(1) Manual Page

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 git(7) suite