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fsck Git Command Guide

The git fsck command is used to verify the connectivity and validity of the objects in the Git database. It checks the integrity of the repository and can help identify and recover from repository corruption or orphaned objects.

git fsck Syntax:

Section titled “git fsck Syntax:”
Terminal window
git fsck [--tags] [--root] [--unreachable] [--cache] [--no-reflogs]
         [--[no-]full] [--strict] [--verbose] [--lost-found]
         [--[no-]dangling] [--[no-]progress] [--connectivity-only]
         [--[no-]name-objects] [--[no-]references] [<object>...]

Options:

Section titled “Options:”
OptionDescription
—tagsReport tags
—rootReport root nodes
—unreachablePrint unreachable objects
—[no-]danglingPrint dangling objects (default: dangling)
—cacheConsider index entries as head nodes
—no-reflogsDon’t consider reflogs for reachability
—[no-]fullCheck alternate object pools (default: full)
—connectivity-onlyCheck only connectivity, skip blob contents
—strictEnable strict checking
—verboseProvide detailed output
—lost-foundWrite dangling objects to .git/lost-found
—name-objectsShow object names with SHAs
—[no-]progressControl progress reporting
—[no-]referencesCheck references database consistency

Parameters:

Section titled “Parameters:”
ParameterDescription
[…]Specific objects to treat as trace heads

git fsck Command Samples:

Section titled “git fsck Command Samples:”

Basic repository integrity check

Section titled “Basic repository integrity check”
Terminal window
git fsck

Check the entire repository for connectivity and validity issues.

Show unreachable objects only

Section titled “Show unreachable objects only”
Terminal window
git fsck --unreachable

Find objects that exist but aren’t reachable from any reference.

Fast connectivity check

Section titled “Fast connectivity check”
Terminal window
git fsck --connectivity-only

Check only connectivity of reachable objects, skip blob content verification.

Verbose checking with names

Section titled “Verbose checking with names”
Terminal window
git fsck --verbose --name-objects

Provide detailed output with descriptive object names.

Check with strict rules

Section titled “Check with strict rules”
Terminal window
git fsck --strict

Enable strict checking to catch issues from older Git versions.

Write dangling objects to files

Section titled “Write dangling objects to files”
Terminal window
git fsck --lost-found

Write dangling objects to .git/lost-found/ for potential recovery.

Check without reflog consideration

Section titled “Check without reflog consideration”
Terminal window
git fsck --no-reflogs

Don’t consider reflog entries when determining reachability.

Full check including alternates

Section titled “Full check including alternates”
Terminal window
git fsck --full

Check not just main object directory but also alternate object pools.

Check from specific commit

Section titled “Check from specific commit”
Terminal window
git fsck HEAD~10

Check integrity starting from a specific commit as head.

Check without progress display

Section titled “Check without progress display”
Terminal window
git fsck --no-progress

Run fsck without progress output.

How do I check repository integrity?

Section titled “How do I check repository integrity?”

To check repository integrity, run:

Terminal window
git fsck

How can I find unreachable objects?

Section titled “How can I find unreachable objects?”

To find unreachable objects, use —unreachable:

Terminal window
git fsck --unreachable

How do I speed up fsck checks?

Section titled “How do I speed up fsck checks?”

To speed up checks, use —connectivity-only to skip blob verification:

Terminal window
git fsck --connectivity-only

How can I recover dangling objects?

Section titled “How can I recover dangling objects?”

To recover dangling objects, use —lost-found to write them to files:

Terminal window
git fsck --lost-found

What’s the difference between unreachable and dangling?

Section titled “What’s the difference between unreachable and dangling?”

Unreachable objects exist but aren’t reachable from refs or reflogs. Dangling objects exist in packs but aren’t directly referenced by other objects.

How do I check only reachable objects?

Section titled “How do I check only reachable objects?”

To check only reachable objects, use —connectivity-only —no-dangling:

Terminal window
git fsck --connectivity-only --no-dangling

How does strict checking differ from normal?

Section titled “How does strict checking differ from normal?”

Strict checking catches additional issues like old Git file modes with g+w bit that modern Git would flag as problems.

When should I use fsck?

Section titled “When should I use fsck?”

Use fsck after repository corruption suspicions, before important operations, or as part of regular repository maintenance.

Can fsck fix corruption?

Section titled “Can fsck fix corruption?”

fsck only detects corruption; it doesn’t repair it. For repair, you may need git fsck results to guide manual recovery or git-repair tools.

How do I check alternates and packed archives?

Section titled “How do I check alternates and packed archives?”

To check all object locations including alternates and packs, use —full (default):

Terminal window
git fsck --full

Applications of the git fsck command

Section titled “Applications of the git fsck command”
  1. Detecting repository corruption and integrity issues
  2. Cleaning up orphaned objects and unreachable commits
  3. Verifying repository health before critical operations
  4. Troubleshooting strange Git behavior or missing objects
  5. Preventive maintenance of important repositories
  6. Debugging synchronization issues between repository copies