{ "mode": "man", "parameter": "git-gc", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/git-gc/1/json", "generated": "2026-09-22T14:23:32Z", "synopsis": "git gc [--aggressive] [--auto] [--quiet] [--prune= | --no-prune] [--force] [--keep-largest-pack]", "sections": { "NAME": { "content": "git-gc - Cleanup unnecessary files and optimize the local repository\n", "subsections": [] }, "SYNOPSIS": { "content": "git gc [--aggressive] [--auto] [--quiet] [--prune= | --no-prune] [--force] [--keep-largest-pack]\n\n", "subsections": [] }, "DESCRIPTION": { "content": "Runs a number of housekeeping tasks within the current repository, such as compressing file\nrevisions (to reduce disk space and increase performance), removing unreachable objects which\nmay have been created from prior invocations of git add, packing refs, pruning reflog, rerere\nmetadata or stale working trees. May also update ancillary indexes such as the commit-graph.\n\nWhen common porcelain operations that create objects are run, they will check whether the\nrepository has grown substantially since the last maintenance, and if so run git gc\nautomatically. See gc.auto below for how to disable this behavior.\n\nRunning git gc manually should only be needed when adding objects to a repository without\nregularly running such porcelain commands, to do a one-off repository optimization, or e.g.\nto clean up a suboptimal mass-import. See the \"PACKFILE OPTIMIZATION\" section in git-fast-\nimport(1) for more details on the import case.\n", "subsections": [] }, "OPTIONS": { "content": "", "subsections": [ { "name": "--aggressive", "content": "Usually git gc runs very quickly while providing good disk space utilization and\nperformance. This option will cause git gc to more aggressively optimize the repository\nat the expense of taking much more time. The effects of this optimization are mostly\npersistent. See the \"AGGRESSIVE\" section below for details.\n", "long": "--aggressive" }, { "name": "--auto", "content": "With this option, git gc checks whether any housekeeping is required; if not, it exits\nwithout performing any work.\n\nSee the gc.auto option in the \"CONFIGURATION\" section below for how this heuristic works.\n\nOnce housekeeping is triggered by exceeding the limits of configuration options such as\ngc.auto and gc.autoPackLimit, all other housekeeping tasks (e.g. rerere, working trees,\nreflog...) will be performed as well.\n\n--[no-]cruft\nWhen expiring unreachable objects, pack them separately into a cruft pack instead of\nstoring them as loose objects. --cruft is on by default.\n\n--max-cruft-size=\nWhen packing unreachable objects into a cruft pack, limit the size of new cruft packs to\nbe at most bytes. Overrides any value specified via the gc.maxCruftSize\nconfiguration. See the --max-cruft-size option of git-repack(1) for more.\n\n--prune=\nPrune loose objects older than date (default is 2 weeks ago, overridable by the config\nvariable gc.pruneExpire). --prune=now prunes loose objects regardless of their age and\nincreases the risk of corruption if another process is writing to the repository\nconcurrently; see \"NOTES\" below. --prune is on by default.\n", "long": "--auto" }, { "name": "--no-prune", "content": "Do not prune any loose objects.\n", "long": "--no-prune" }, { "name": "--quiet", "content": "Suppress all progress reports.\n", "long": "--quiet" }, { "name": "--force", "content": "Force git gc to run even if there may be another git gc instance running on this\nrepository.\n", "long": "--force" }, { "name": "--keep-largest-pack", "content": "All packs except the largest non-cruft pack, any packs marked with a .keep file, and any\ncruft pack(s) are consolidated into a single pack. When this option is used,\ngc.bigPackThreshold is ignored.\n", "long": "--keep-largest-pack" } ] }, "AGGRESSIVE": { "content": "When the --aggressive option is supplied, git-repack(1) will be invoked with the -f flag,\nwhich in turn will pass --no-reuse-delta to git-pack-objects(1). This will throw away any\nexisting deltas and re-compute them, at the expense of spending much more time on the\nrepacking.\n\nThe effects of this are mostly persistent, e.g. when packs and loose objects are coalesced\ninto one another pack the existing deltas in that pack might get re-used, but there are also\nvarious cases where we might pick a sub-optimal delta from a newer pack instead.\n\nFurthermore, supplying --aggressive will tweak the --depth and --window options passed to\ngit-repack(1). See the gc.aggressiveDepth and gc.aggressiveWindow settings below. By using a\nlarger window size we’re more likely to find more optimal deltas.\n\nIt’s probably not worth it to use this option on a given repository without running tailored\nperformance benchmarks on it. It takes a lot more time, and the resulting space/delta\noptimization may or may not be worth it. Not using this at all is the right trade-off for\nmost users and their repositories.\n", "subsections": [] }, "CONFIGURATION": { "content": "Everything below this line in this section is selectively included from the git-config(1)\ndocumentation. The content is the same as what’s found there:\n\ngc.aggressiveDepth\nThe depth parameter used in the delta compression algorithm used by git gc --aggressive.\nThis defaults to 50, which is the default for the --depth option when --aggressive isn’t\nin use.\n\nSee the documentation for the --depth option in git-repack(1) for more details.\n\ngc.aggressiveWindow\nThe window size parameter used in the delta compression algorithm used by git gc\n--aggressive. This defaults to 250, which is a much more aggressive window size than the\ndefault --window of 10.\n\nSee the documentation for the --window option in git-repack(1) for more details.\n\ngc.auto\nWhen there are approximately more than this many loose objects in the repository, git gc\n--auto will pack them. Some Porcelain commands use this command to perform a light-weight\ngarbage collection from time to time. The default value is 6700.\n\nSetting this to 0 disables not only automatic packing based on the number of loose\nobjects, but also any other heuristic git gc --auto will otherwise use to determine if\nthere’s work to do, such as gc.autoPackLimit.\n\ngc.autoPackLimit\nWhen there are more than this many packs that are not marked with *.keep file in the\nrepository, git gc --auto consolidates them into one larger pack. The default value is\n50. Setting this to 0 disables it. Setting gc.auto to 0 will also disable this.\n\nSee the gc.bigPackThreshold configuration variable below. When in use, it’ll affect how\nthe auto pack limit works.\n\ngc.autoDetach\nMake git gc --auto return immediately and run in the background if the system supports\nit. Default is true.\n\ngc.bigPackThreshold\nIf non-zero, all non-cruft packs larger than this limit are kept when git gc is run. This\nis very similar to --keep-largest-pack except that all non-cruft packs that meet the\nthreshold are kept, not just the largest pack. Defaults to zero. Common unit suffixes of\nk, m, or g are supported.\n\nNote that if the number of kept packs is more than gc.autoPackLimit, this configuration\nvariable is ignored, all packs except the base pack will be repacked. After this the\nnumber of packs should go below gc.autoPackLimit and gc.bigPackThreshold should be\nrespected again.\n\nIf the amount of memory estimated for git repack to run smoothly is not available and\ngc.bigPackThreshold is not set, the largest pack will also be excluded (this is the\nequivalent of running git gc with --keep-largest-pack).\n\ngc.writeCommitGraph\nIf true, then gc will rewrite the commit-graph file when git-gc(1) is run. When using git\ngc --auto the commit-graph will be updated if housekeeping is required. Default is true.\nSee git-commit-graph(1) for details.\n\ngc.logExpiry\nIf the file gc.log exists, then git gc --auto will print its content and exit with status\nzero instead of running unless that file is more than gc.logExpiry old. Default is\n\"1.day\". See gc.pruneExpire for more ways to specify its value.\n\ngc.packRefs\nRunning git pack-refs in a repository renders it unclonable by Git versions prior to\n1.5.1.2 over dumb transports such as HTTP. This variable determines whether git gc runs\ngit pack-refs. This can be set to notbare to enable it within all non-bare repos or it\ncan be set to a boolean value. The default is true.\n\ngc.cruftPacks\nStore unreachable objects in a cruft pack (see git-repack(1)) instead of as loose\nobjects. The default is true.\n\ngc.maxCruftSize\nLimit the size of new cruft packs when repacking. When specified in addition to\n--max-cruft-size, the command line option takes priority. See the --max-cruft-size option\nof git-repack(1).\n\ngc.pruneExpire\nWhen git gc is run, it will call prune --expire 2.weeks.ago (and repack --cruft\n--cruft-expiration 2.weeks.ago if using cruft packs via gc.cruftPacks or --cruft).\nOverride the grace period with this config variable. The value \"now\" may be used to\ndisable this grace period and always prune unreachable objects immediately, or \"never\"\nmay be used to suppress pruning. This feature helps prevent corruption when git gc runs\nconcurrently with another process writing to the repository; see the \"NOTES\" section of\ngit-gc(1).\n\ngc.worktreePruneExpire\nWhen git gc is run, it calls git worktree prune --expire 3.months.ago. This config\nvariable can be used to set a different grace period. The value \"now\" may be used to\ndisable the grace period and prune $GITDIR/worktrees immediately, or \"never\" may be used\nto suppress pruning.\n\ngc.reflogExpire, gc..reflogExpire\ngit reflog expire removes reflog entries older than this time; defaults to 90 days. The\nvalue \"now\" expires all entries immediately, and \"never\" suppresses expiration\naltogether. With \"\" (e.g. \"refs/stash\") in the middle the setting applies only\nto the refs that match the .\n\ngc.reflogExpireUnreachable, gc..reflogExpireUnreachable\ngit reflog expire removes reflog entries older than this time and are not reachable from\nthe current tip; defaults to 30 days. The value \"now\" expires all entries immediately,\nand \"never\" suppresses expiration altogether. With \"\" (e.g. \"refs/stash\") in the\nmiddle, the setting applies only to the refs that match the .\n\nThese types of entries are generally created as a result of using git commit --amend or\ngit rebase and are the commits prior to the amend or rebase occurring. Since these\nchanges are not part of the current project most users will want to expire them sooner,\nwhich is why the default is more aggressive than gc.reflogExpire.\n\ngc.recentObjectsHook\nWhen considering whether or not to remove an object (either when generating a cruft pack\nor storing unreachable objects as loose), use the shell to execute the specified\ncommand(s). Interpret their output as object IDs which Git will consider as \"recent\",\nregardless of their age. By treating their mtimes as \"now\", any objects (and their\ndescendants) mentioned in the output will be kept regardless of their true age.\n\nOutput must contain exactly one hex object ID per line, and nothing else. Objects which\ncannot be found in the repository are ignored. Multiple hooks are supported, but all must\nexit successfully, else the operation (either generating a cruft pack or unpacking\nunreachable objects) will be halted.\n\ngc.repackFilter\nWhen repacking, use the specified filter to move certain objects into a separate\npackfile. See the --filter= option of git-repack(1).\n\ngc.repackFilterTo\nWhen repacking and using a filter, see gc.repackFilter, the specified location will be\nused to create the packfile containing the filtered out objects. WARNING: The specified\nlocation should be accessible, using for example the Git alternates mechanism, otherwise\nthe repo could be considered corrupt by Git as it migh not be able to access the objects\nin that packfile. See the --filter-to= option of git-repack(1) and the\nobjects/info/alternates section of gitrepository-layout(5).\n\ngc.rerereResolved\nRecords of conflicted merge you resolved earlier are kept for this many days when git\nrerere gc is run. You can also use more human-readable \"1.month.ago\", etc. The default is\n60 days. See git-rerere(1).\n\ngc.rerereUnresolved\nRecords of conflicted merge you have not resolved are kept for this many days when git\nrerere gc is run. You can also use more human-readable \"1.month.ago\", etc. The default is\n15 days. See git-rerere(1).\n", "subsections": [] }, "NOTES": { "content": "git gc tries very hard not to delete objects that are referenced anywhere in your repository.\nIn particular, it will keep not only objects referenced by your current set of branches and\ntags, but also objects referenced by the index, remote-tracking branches, reflogs (which may\nreference commits in branches that were later amended or rewound), and anything else in the\nrefs/* namespace. Note that a note (of the kind created by git notes) attached to an object\ndoes not contribute in keeping the object alive. If you are expecting some objects to be\ndeleted and they aren’t, check all of those locations and decide whether it makes sense in\nyour case to remove those references.\n\nOn the other hand, when git gc runs concurrently with another process, there is a risk of it\ndeleting an object that the other process is using but hasn’t created a reference to. This\nmay just cause the other process to fail or may corrupt the repository if the other process\nlater adds a reference to the deleted object. Git has two features that significantly\nmitigate this problem:\n\n1. Any object with modification time newer than the --prune date is kept, along with\neverything reachable from it.\n\n2. Most operations that add an object to the database update the modification time of the\nobject if it is already present so that #1 applies.\n\nHowever, these features fall short of a complete solution, so users who run commands\nconcurrently have to live with some risk of corruption (which seems to be low in practice).\n", "subsections": [] }, "HOOKS": { "content": "The git gc --auto command will run the pre-auto-gc hook. See githooks(5) for more\ninformation.\n", "subsections": [] }, "SEE ALSO": { "content": "git-prune(1) git-reflog(1) git-repack(1) git-rerere(1)\n", "subsections": [] }, "GIT": { "content": "Part of the git(1) suite\n\nGit 2.43.0 07/02/2025 GIT-GC(1)", "subsections": [] } }, "summary": "git-gc - Cleanup unnecessary files and optimize the local repository", "flags": [ { "flag": "", "long": "--aggressive", "arg": null, "description": "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." }, { "flag": "", "long": "--auto", "arg": null, "description": "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. --[no-]cruft When expiring unreachable objects, pack them separately into a cruft pack instead of storing them as loose objects. --cruft is on by default. --max-cruft-size= When packing unreachable objects into a cruft pack, limit the size of new cruft packs to be at most bytes. Overrides any value specified via the gc.maxCruftSize configuration. See the --max-cruft-size option of git-repack(1) for more. --prune= 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." }, { "flag": "", "long": "--no-prune", "arg": null, "description": "Do not prune any loose objects." }, { "flag": "", "long": "--quiet", "arg": null, "description": "Suppress all progress reports." }, { "flag": "", "long": "--force", "arg": null, "description": "Force git gc to run even if there may be another git gc instance running on this repository." }, { "flag": "", "long": "--keep-largest-pack", "arg": null, "description": "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." } ], "examples": [], "see_also": [ { "name": "git-prune", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/git-prune/1/json" }, { "name": "git-reflog", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/git-reflog/1/json" }, { "name": "git-repack", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/git-repack/1/json" }, { "name": "git-rerere", "section": "1", "url": "https://www.chedong.com/phpMan.php/man/git-rerere/1/json" } ], "tldr": { "source": "official", "description": "Optimise the local repository by cleaning unnecessary files.", "examples": [ { "description": "Optimise the repository", "command": "git gc" }, { "description": "Aggressively optimise, takes more time", "command": "git gc --aggressive" }, { "description": "Do not prune loose objects (prunes by default)", "command": "git gc --no-prune" }, { "description": "Suppress all output", "command": "git gc --quiet" }, { "description": "Display help", "command": "git gc --help" } ] } }