NAME¶
git-fsck - Verifies the connectivity and validity of the objects
    in the database
SYNOPSIS¶
git fsck [--tags] [--root] [--unreachable] [--cache] [--no-reflogs]
         [--[no-]full] [--strict] [--verbose] [--lost-found]
         [--[no-]dangling] [--[no-]progress] [<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 defaults to using the
    index file, all SHA-1 references in refs namespace, and all reflogs (unless
    --no-reflogs is given) as heads.
--unreachable
Print out objects that exist but that aren’t
  reachable from any of the reference nodes.
--[no-]dangling
Print objects that exist but that are never
  directly used (default). --no-dangling can be used to omit this
  information from the output.
--root
Report root nodes.
--tags
Report tags.
--cache
Consider any object recorded in the index also as a head
  node for an unreachability trace.
--no-reflogs
Do not consider commits that are referenced only by an
  entry in a reflog to be reachable. This option is meant only to search for
  commits that used to be in a ref, but now aren’t, but are still in that
  corresponding reflog.
--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 or $GIT_DIR/objects/info/alternates, and
  in packed Git archives found in $GIT_DIR/objects/pack and corresponding pack
  subdirectories in alternate object pools. This is now default; you can turn it
  off with --no-full.
--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.
--verbose
Be chatty.
--lost-found
Write dangling objects into .git/lost-found/commit/ or
  .git/lost-found/other/, depending on type. If the object is a blob, the
  contents are written into the file, rather than its object name.
--[no-]progress
Progress status is reported on the standard error stream
  by default when it is attached to a terminal, unless --no-progress or
  --verbose is specified. --progress forces progress status even if the standard
  error stream is not directed to a terminal.
DISCUSSION¶
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).
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.
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)