git fsck [--tags] [--root] [--unreachable] [--cache] [--no-reflogs] [--[no-]full] [--strict] [--verbose] [--lost-found] [--[no-]dangling] [--[no-]progress] [--connectivity-only] [--[no-]name-objects] [<object>*]
If no objects are given, git fsck defaults to using the index file, all SHA-1 references in refs namespace, and all reflogs (unless --no-reflogs is given) as heads.
Unreachable tags, commits, and trees will also be accessed to find the tips of dangling segments of history. Use --no-dangling if you don't care about this output and want to speed it up further.
Setting fsck.<msg-id> will be picked up by git-fsck(1), but to accept pushes of such data set receive.fsck.<msg-id> instead, or to clone or fetch it set fetch.fsck.<msg-id>.
The rest of the documentation discusses fsck.* for brevity, but the same applies for the corresponding receive.fsck.* and fetch.<msg-id>.*. variables.
Unlike variables like color.ui and core.editor the receive.fsck.<msg-id> and fetch.fsck.<msg-id> variables will not fall back on the fsck.<msg-id> configuration if they aren't set. To uniformly configure the same fsck settings in different circumstances all three of them they must all set to the same values.
When fsck.<msg-id> is set, errors can be switched to warnings and vice versa by configuring the fsck.<msg-id> setting where the <msg-id> is the fsck message ID and the value is one of error, warn or ignore. For convenience, fsck prefixes the error/warning with the message ID, e.g. "missingEmail: invalid author/committer line - missing email" means that setting fsck.missingEmail = ignore will hide that issue.
In general, it is better to enumerate existing objects with problems with fsck.skipList, instead of listing the kind of breakages these problematic objects share to be ignored, as doing the latter will allow new instances of the same breakages go unnoticed.
Setting an unknown fsck.<msg-id> value will cause fsck to die, but doing the same for receive.fsck.<msg-id> and fetch.fsck.<msg-id> will only cause git to warn.
This feature is useful when an established project should be accepted despite early commits containing errors that can be safely ignored such as invalid committer email addresses. Note: corrupt objects cannot be skipped with this setting.
Like fsck.<msg-id> this variable has corresponding receive.fsck.skipList and fetch.fsck.skipList variants.
Unlike variables like color.ui and core.editor the receive.fsck.skipList and fetch.fsck.skipList variables will not fall back on the fsck.skipList configuration if they aren't set. To uniformly configure the same fsck settings in different circumstances all three of them they must all set to the same values.
Older versions of Git (before 2.20) documented that the object names list should be sorted. This was never a requirement, the object names could appear in any order, but when reading the list we tracked whether the list was sorted for the purposes of an internal binary search implementation, which could save itself some work with an already sorted list. Unless you had a humongous list there was no reason to go out of your way to pre-sort the list. After Git version 2.20 a hash implementation is used instead, so there's now no reason to pre-sort the list.
git-fsck tests SHA-1 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 reachable from any of the specified head nodes (or the default set, as mentioned above).
Any corrupt objects you will have to find in backups or other archives (i.e., 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).
If core.commitGraph is true, the commit-graph file will also be inspected using git commit-graph verify. See git-commit-graph(1).
expect dangling commits - potential heads - due to lack of head information
missing sha1 directory <dir>
unreachable <type> <object>
missing <type> <object>
dangling <type> <object>
hash mismatch <object>
Part of the git(1) suite