NAME

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

SYNOPSIS

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

DESCRIPTION

       Runs a number of housekeeping tasks within the current repository, such as compressing
       file revisions (to reduce disk space and increase performance) and removing unreachable
       objects which may have been created from prior invocations of git add.

       Users are encouraged to run this task on a regular basis within each repository to
       maintain good disk space utilization and good operating performance.

       Some git commands may automatically run git gc; see the --auto flag below for details. If
       you know what you’re doing and all you want is to disable this behavior permanently
       without further considerations, just do:

           $ git config --global gc.auto 0

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 persistent, so this option only needs to be used occasionally; every few hundred
           changesets or so.

       --auto
           With this option, git gc checks whether any housekeeping is required; if not, it exits
           without performing any work. Some git commands run git gc --auto after performing
           operations that could create many loose objects.

           Housekeeping is required if there are too many loose objects or too many packs in the
           repository. If the number of loose objects exceeds the value of the gc.auto
           configuration variable, then all loose objects are combined into a single pack using
           git repack -d -l. Setting the value of gc.auto to 0 disables automatic packing of
           loose objects.

           If the number of packs exceeds the value of gc.autoPackLimit, then existing packs
           (except those marked with a .keep file) are consolidated into a single pack by using
           the -A option of git repack. Setting gc.autoPackLimit to 0 disables automatic
           consolidation of packs.

       --prune=<date>
           Prune loose objects older than date (default is 2 weeks ago, overridable by the config
           variable gc.pruneExpire). --prune=all 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.

CONFIGURATION

       The optional configuration variable gc.reflogExpire can be set to indicate how long
       historical entries within each branch’s reflog should remain available in this repository.
       The setting is expressed as a length of time, for example 90 days or 3 months. It defaults
       to 90 days.

       The optional configuration variable gc.reflogExpireUnreachable can be set to indicate how
       long historical reflog entries which are not part of the current branch should remain
       available in this repository. 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. This option defaults to 30 days.

       The above two configuration variables can be given to a pattern. For example, this sets
       non-default expiry values only to remote-tracking branches:

           [gc "refs/remotes/*"]
                   reflogExpire = never
                   reflogExpireUnreachable = 3 days

       The optional configuration variable gc.rerereResolved indicates how long records of
       conflicted merge you resolved earlier are kept. This defaults to 60 days.

       The optional configuration variable gc.rerereUnresolved indicates how long records of
       conflicted merge you have not resolved are kept. This defaults to 15 days.

       The optional configuration variable gc.packRefs determines if 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. This defaults to true.

       The optional configuration variable ‘gc.aggressiveWindow` controls how much time is spent
       optimizing the delta compression of the objects in the repository when the --aggressive
       option is specified. The larger the value, the more time is spent optimizing the delta
       compression. See the documentation for the --window’ option in git-repack(1) for more
       details. This defaults to 250.

       Similarly, the optional configuration variable gc.aggressiveDepth controls --depth option
       in git-repack(1). This defaults to 50.

       The optional configuration variable gc.pruneExpire controls how old the unreferenced loose
       objects have to be before they are pruned. The default is "2 weeks ago".

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,
       refs saved by git filter-branch in refs/original/, or reflogs (which may reference commits
       in branches that were later amended or rewound). 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)
       unless they turn off automatic garbage collection with git config gc.auto 0.

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