GIT-GC(1) - man - phpMan

GIT-GC(1)                                    Git Manual                                    GIT-GC(1)



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

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


DESCRIPTION
       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 gc.auto 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.

OPTIONS
       --aggressive
           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.

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

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

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

       --prune=<date>
           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.

       --no-prune
           Do not prune any loose objects.

       --quiet
           Suppress all progress reports.

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

       --keep-largest-pack
           All packs except the largest pack and those marked with a .keep files are consolidated
           into a single pack. When this option is used, gc.bigPackThreshold is ignored.

AGGRESSIVE
       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.

CONFIGURATION
       The below documentation is the same as what’s found in git-config(1):

       gc.aggressiveDepth
           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.

       gc.aggressiveWindow
           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.

       gc.auto
           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 gc.autoPackLimit.

       gc.autoPackLimit
           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 gc.auto 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.

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

       gc.bigPackThreshold
           If non-zero, all packs larger than this limit are kept when git gc is run. This is very
           similar to --keep-largest-pack except that all 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).

       gc.writeCommitGraph
           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.

       gc.logExpiry
           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
           "1.day". See gc.pruneExpire for more ways to specify its value.

       gc.packRefs
           Running git pack-refs in a repository renders it unclonable by Git versions prior to
           1.5.1.2 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.

       gc.pruneExpire
           When git gc is run, it will call prune --expire 2.weeks.ago. 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).

       gc.worktreePruneExpire
           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 <pattern>.

           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.

       gc.rerereResolved
           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-rerere(1).

       gc.rerereUnresolved
           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-rerere(1).

NOTES
       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 applies.

       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).

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

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

GIT
       Part of the git(1) suite



Git 2.34.1                                   02/26/2026                                    GIT-GC(1)