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git-gc(1)                         Git Manual                         git-gc(1)


       git-gc - Cleanup unnecessary files and optimize the local repository


       git gc [--aggressive] [--auto] [--quiet] [--prune=<date> | --no-prune] [--force] [--keep-largest-pack]


       Runs a number of housekeeping tasks within the current repository, such
       as compressing file revisions (to reduce disk space and increase
       performance), removing unreachable objects which may have been created
       from prior invocations of git add, packing refs, pruning reflog, rerere
       metadata or stale working trees. May also update ancillary indexes such
       as the commit-graph.

       When common porcelain operations that create objects are run, they will
       check whether the repository has grown substantially since the last
       maintenance, and if so run git gc automatically. See below for
       how to disable this behavior.

       Running git gc manually should only be needed when adding objects to a
       repository without regularly running such porcelain commands, to do a
       one-off repository optimization, or e.g. to clean up a suboptimal
       mass-import. See the "PACKFILE OPTIMIZATION" section in git-fast-
       import(1) for more details on the import case.


           Usually git gc runs very quickly while providing good disk space
           utilization and performance. This option will cause git gc to more
           aggressively optimize the repository at the expense of taking much
           more time. The effects of this optimization are mostly persistent.
           See the "AGGRESSIVE" section below for details.

           With this option, git gc checks whether any housekeeping is
           required; if not, it exits without performing any work.

           See the option in the "CONFIGURATION" section below for how
           this heuristic works.

           Once housekeeping is triggered by exceeding the limits of
           configuration options such as and gc.autoPackLimit, all
           other housekeeping tasks (e.g. rerere, working trees, reflog...)
           will be performed as well.

           When expiring unreachable objects, pack them separately into a
           cruft pack instead of storing them as loose objects.  --cruft is on
           by default.

           Prune loose objects older than date (default is 2 weeks ago,
           overridable by the config variable gc.pruneExpire). --prune=now
           prunes loose objects regardless of their age and increases the risk
           of corruption if another process is writing to the repository
           concurrently; see "NOTES" below. --prune is on by default.

           Do not prune any loose objects.

           Suppress all progress reports.

           Force git gc to run even if there may be another git gc instance
           running on this repository.

           All packs except the largest non-cruft pack, any packs marked with
           a .keep file, and any cruft pack(s) are consolidated into a single
           pack. When this option is used, gc.bigPackThreshold is ignored.


       When the --aggressive option is supplied, git-repack(1) will be invoked
       with the -f flag, which in turn will pass --no-reuse-delta to git-pack-
       objects(1). This will throw away any existing deltas and re-compute
       them, at the expense of spending much more time on the repacking.

       The effects of this are mostly persistent, e.g. when packs and loose
       objects are coalesced into one another pack the existing deltas in that
       pack might get re-used, but there are also various cases where we might
       pick a sub-optimal delta from a newer pack instead.

       Furthermore, supplying --aggressive will tweak the --depth and --window
       options passed to git-repack(1). See the gc.aggressiveDepth and
       gc.aggressiveWindow settings below. By using a larger window size we're
       more likely to find more optimal deltas.

       It's probably not worth it to use this option on a given repository
       without running tailored performance benchmarks on it. It takes a lot
       more time, and the resulting space/delta optimization may or may not be
       worth it. Not using this at all is the right trade-off for most users
       and their repositories.


       Everything below this line in this section is selectively included from
       the git-config(1) documentation. The content is the same as what's
       found there:

           The depth parameter used in the delta compression algorithm used by
           git gc --aggressive. This defaults to 50, which is the default for
           the --depth option when --aggressive isn't in use.

           See the documentation for the --depth option in git-repack(1) for
           more details.

           The window size parameter used in the delta compression algorithm
           used by git gc --aggressive. This defaults to 250, which is a much
           more aggressive window size than the default --window of 10.

           See the documentation for the --window option in git-repack(1) for
           more details.
           When there are approximately more than this many loose objects in
           the repository, git gc --auto will pack them. Some Porcelain
           commands use this command to perform a light-weight garbage
           collection from time to time. The default value is 6700.

           Setting this to 0 disables not only automatic packing based on the
           number of loose objects, but any other heuristic git gc --auto will
           otherwise use to determine if there's work to do, such as

           When there are more than this many packs that are not marked with
           *.keep file in the repository, git gc --auto consolidates them into
           one larger pack. The default value is 50. Setting this to 0
           disables it. Setting to 0 will also disable this.

           See the gc.bigPackThreshold configuration variable below. When in
           use, it'll affect how the auto pack limit works.

           Make git gc --auto return immediately and run in background if the
           system supports it. Default is true.

           If non-zero, all non-cruft packs larger than this limit are kept
           when git gc is run. This is very similar to --keep-largest-pack
           except that all non-cruft packs that meet the threshold are kept,
           not just the largest pack. Defaults to zero. Common unit suffixes
           of k, m, or g are supported.

           Note that if the number of kept packs is more than
           gc.autoPackLimit, this configuration variable is ignored, all packs
           except the base pack will be repacked. After this the number of
           packs should go below gc.autoPackLimit and gc.bigPackThreshold
           should be respected again.

           If the amount of memory estimated for git repack to run smoothly is
           not available and gc.bigPackThreshold is not set, the largest pack
           will also be excluded (this is the equivalent of running git gc
           with --keep-largest-pack).

           If true, then gc will rewrite the commit-graph file when git-gc(1)
           is run. When using git gc --auto the commit-graph will be updated
           if housekeeping is required. Default is true. See git-commit-
       graph(1) for details.

           If the file gc.log exists, then git gc --auto will print its
           content and exit with status zero instead of running unless that
           file is more than gc.logExpiry old. Default is "". See
           gc.pruneExpire for more ways to specify its value.

           Running git pack-refs in a repository renders it unclonable by Git
           versions prior to over dumb transports such as HTTP. This
           variable determines whether git gc runs git pack-refs. This can be
           set to notbare to enable it within all non-bare repos or it can be
           set to a boolean value. The default is true.

           Store unreachable objects in a cruft pack (see git-repack(1))
           instead of as loose objects. The default is true.

           When git gc is run, it will call prune --expire 2.weeks.ago (and
           repack --cruft --cruft-expiration 2.weeks.ago if using cruft packs
           via gc.cruftPacks or --cruft). Override the grace period with this
           config variable. The value "now" may be used to disable this grace
           period and always prune unreachable objects immediately, or "never"
           may be used to suppress pruning. This feature helps prevent
           corruption when git gc runs concurrently with another process
           writing to the repository; see the "NOTES" section of git-gc(1).

           When git gc is run, it calls git worktree prune --expire
           3.months.ago. This config variable can be used to set a different
           grace period. The value "now" may be used to disable the grace
           period and prune $GIT_DIR/worktrees immediately, or "never" may be
           used to suppress pruning.

       gc.reflogExpire, gc.<pattern>.reflogExpire
           git reflog expire removes reflog entries older than this time;
           defaults to 90 days. The value "now" expires all entries
           immediately, and "never" suppresses expiration altogether. With
           "<pattern>" (e.g. "refs/stash") in the middle the setting applies
           only to the refs that match the <pattern>.

       gc.reflogExpireUnreachable, gc.<pattern>.reflogExpireUnreachable
           git reflog expire removes reflog entries older than this time and
           are not reachable from the current tip; defaults to 30 days. The
           value "now" expires all entries immediately, and "never" suppresses
           expiration altogether. With "<pattern>" (e.g. "refs/stash") in the
           middle, the setting applies only to the refs that match the

           These types of entries are generally created as a result of using
           git commit --amend or git rebase and are the commits prior to the
           amend or rebase occurring. Since these changes are not part of the
           current project most users will want to expire them sooner, which
           is why the default is more aggressive than gc.reflogExpire.

           When considering whether or not to remove an object (either when
           generating a cruft pack or storing unreachable objects as loose),
           use the shell to execute the specified command(s). Interpret their
           output as object IDs which Git will consider as "recent",
           regardless of their age. By treating their mtimes as "now", any
           objects (and their descendants) mentioned in the output will be
           kept regardless of their true age.

           Output must contain exactly one hex object ID per line, and nothing
           else. Objects which cannot be found in the repository are ignored.
           Multiple hooks are supported, but all must exit successfully, else
           the operation (either generating a cruft pack or unpacking
           unreachable objects) will be halted.

           Records of conflicted merge you resolved earlier are kept for this
           many days when git rerere gc is run. You can also use more
           human-readable "1.month.ago", etc. The default is 60 days. See git-

           Records of conflicted merge you have not resolved are kept for this
           many days when git rerere gc is run. You can also use more
           human-readable "1.month.ago", etc. The default is 15 days. See git-


       git gc tries very hard not to delete objects that are referenced
       anywhere in your repository. In particular, it will keep not only
       objects referenced by your current set of branches and tags, but also
       objects referenced by the index, remote-tracking branches, reflogs
       (which may reference commits in branches that were later amended or
       rewound), and anything else in the refs/* namespace. Note that a note
       (of the kind created by git notes) attached to an object does not
       contribute in keeping the object alive. If you are expecting some
       objects to be deleted and they aren't, check all of those locations and
       decide whether it makes sense in your case to remove those references.

       On the other hand, when git gc runs concurrently with another process,
       there is a risk of it deleting an object that the other process is
       using but hasn't created a reference to. This may just cause the other
       process to fail or may corrupt the repository if the other process
       later adds a reference to the deleted object. Git has two features that
       significantly mitigate this problem:

        1. Any object with modification time newer than the --prune date is
           kept, along with everything reachable from it.

        2. Most operations that add an object to the database update the
           modification time of the object if it is already present so that #1

       However, these features fall short of a complete solution, so users who
       run commands concurrently have to live with some risk of corruption
       (which seems to be low in practice).


       The git gc --auto command will run the pre-auto-gc hook. See
       githooks(5) for more information.


       git-prune(1) git-reflog(1) git-repack(1) git-rerere(1)


       Part of the git(1) suite

Git 2.42.0                        2023-08-21                         git-gc(1)

git 2.42.0 - Generated Mon Aug 28 18:56:45 CDT 2023
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