Documentation / git-fsck.txton commit do not write null sha1s to on-disk index (4337b58)
   1git-fsck(1)
   2===========
   3
   4NAME
   5----
   6git-fsck - Verifies the connectivity and validity of the objects in the database
   7
   8
   9SYNOPSIS
  10--------
  11[verse]
  12'git fsck' [--tags] [--root] [--unreachable] [--cache] [--no-reflogs]
  13         [--[no-]full] [--strict] [--verbose] [--lost-found]
  14         [--[no-]progress] [<object>*]
  15
  16DESCRIPTION
  17-----------
  18Verifies the connectivity and validity of the objects in the database.
  19
  20OPTIONS
  21-------
  22<object>::
  23        An object to treat as the head of an unreachability trace.
  24+
  25If no objects are given, 'git fsck' defaults to using the
  26index file, all SHA1 references in .git/refs/*, and all reflogs (unless
  27--no-reflogs is given) as heads.
  28
  29--unreachable::
  30        Print out objects that exist but that aren't reachable from any
  31        of the reference nodes.
  32
  33--root::
  34        Report root nodes.
  35
  36--tags::
  37        Report tags.
  38
  39--cache::
  40        Consider any object recorded in the index also as a head node for
  41        an unreachability trace.
  42
  43--no-reflogs::
  44        Do not consider commits that are referenced only by an
  45        entry in a reflog to be reachable.  This option is meant
  46        only to search for commits that used to be in a ref, but
  47        now aren't, but are still in that corresponding reflog.
  48
  49--full::
  50        Check not just objects in GIT_OBJECT_DIRECTORY
  51        ($GIT_DIR/objects), but also the ones found in alternate
  52        object pools listed in GIT_ALTERNATE_OBJECT_DIRECTORIES
  53        or $GIT_DIR/objects/info/alternates,
  54        and in packed git archives found in $GIT_DIR/objects/pack
  55        and corresponding pack subdirectories in alternate
  56        object pools.  This is now default; you can turn it off
  57        with --no-full.
  58
  59--strict::
  60        Enable more strict checking, namely to catch a file mode
  61        recorded with g+w bit set, which was created by older
  62        versions of git.  Existing repositories, including the
  63        Linux kernel, git itself, and sparse repository have old
  64        objects that triggers this check, but it is recommended
  65        to check new projects with this flag.
  66
  67--verbose::
  68        Be chatty.
  69
  70--lost-found::
  71        Write dangling objects into .git/lost-found/commit/ or
  72        .git/lost-found/other/, depending on type.  If the object is
  73        a blob, the contents are written into the file, rather than
  74        its object name.
  75
  76--progress::
  77--no-progress::
  78        Progress status is reported on the standard error stream by
  79        default when it is attached to a terminal, unless
  80        --no-progress or --verbose is specified. --progress forces
  81        progress status even if the standard error stream is not
  82        directed to a terminal.
  83
  84DISCUSSION
  85----------
  86
  87git-fsck tests SHA1 and general object sanity, and it does full tracking
  88of the resulting reachability and everything else. It prints out any
  89corruption it finds (missing or bad objects), and if you use the
  90'--unreachable' flag it will also print out objects that exist but that
  91aren't reachable from any of the specified head nodes (or the default
  92set, as mentioned above).
  93
  94Any corrupt objects you will have to find in backups or other archives
  95(i.e., you can just remove them and do an 'rsync' with some other site in
  96the hopes that somebody else has the object you have corrupted).
  97
  98Extracted Diagnostics
  99---------------------
 100
 101expect dangling commits - potential heads - due to lack of head information::
 102        You haven't specified any nodes as heads so it won't be
 103        possible to differentiate between un-parented commits and
 104        root nodes.
 105
 106missing sha1 directory '<dir>'::
 107        The directory holding the sha1 objects is missing.
 108
 109unreachable <type> <object>::
 110        The <type> object <object>, isn't actually referred to directly
 111        or indirectly in any of the trees or commits seen. This can
 112        mean that there's another root node that you're not specifying
 113        or that the tree is corrupt. If you haven't missed a root node
 114        then you might as well delete unreachable nodes since they
 115        can't be used.
 116
 117missing <type> <object>::
 118        The <type> object <object>, is referred to but isn't present in
 119        the database.
 120
 121dangling <type> <object>::
 122        The <type> object <object>, is present in the database but never
 123        'directly' used. A dangling commit could be a root node.
 124
 125sha1 mismatch <object>::
 126        The database has an object who's sha1 doesn't match the
 127        database value.
 128        This indicates a serious data integrity problem.
 129
 130Environment Variables
 131---------------------
 132
 133GIT_OBJECT_DIRECTORY::
 134        used to specify the object database root (usually $GIT_DIR/objects)
 135
 136GIT_INDEX_FILE::
 137        used to specify the index file of the index
 138
 139GIT_ALTERNATE_OBJECT_DIRECTORIES::
 140        used to specify additional object database roots (usually unset)
 141
 142GIT
 143---
 144Part of the linkgit:git[1] suite