git reflog

Your safety net. Almost everything you 'lost' is in here.

🎯 What & why

git reflog records every move of every ref tip — commits, resets, rebases, checkouts, the works. It's your local, private, time-travel log and the single most important recovery tool in Git.

🧠 Mental model

Branches are pointers. The reflog is the history of where each pointer has been. Even a reset --hard to oblivion leaves a breadcrumb here for ~90 days.

🛠️ Synopsis

git reflog [show] [<options>] [<ref>]
git reflog expire [--expire=<time>] [--expire-unreachable=<time>]
                  [--rewrite] [--updateref] [--stale-fix] [--all|<refs>...]
git reflog delete <ref>@{<specifier>}...
git reflog exists <ref>

🎚️ Switches & options

Flag	What it does
`--all`	Operate on reflogs of every ref, not just HEAD.
`--expire=<time>`	Drop entries older than `<time>` (default 90 days, `gc.reflogExpire`).
`--expire-unreachable=<time>`	Drop unreachable entries older than `<time>` (default 30 days).
`-n <num>`	Limit `show` output.
`--date=<format>`	Format timestamps: `relative`, `iso`, `short`, ...
`git reflog expire --expire=now --all`	⚠️ Wipes your safety net. Combined with `gc --prune=now`, recovery is over.

📦 Subcommands

show — Print reflog entries (default subcommand).

git reflog show master

expire — Trim old/unreachable reflog entries. gc runs this for you.

git reflog expire --expire=30.days --all

delete — Drop a specific reflog entry by <ref>@{n} selector.

git reflog delete HEAD@{2}

exists — Exit 0 if a reflog exists for <ref>. Useful in scripts.

git reflog exists refs/heads/topic

💡 Use cases

Oh god I just reset --hard — git reset --hard HEAD@{1} brings it back.
Lost a branch you deleted — find its last tip in git reflog and git branch <name> <sha>.
Botched rebase — git reflog shows the pre-rebase HEAD; reset to it.
Audit what you did last week without trusting commit dates.

🧪 Examples

The classic undo

git reflog
git reset --hard HEAD@{1}

Recover a deleted branch

git reflog --all | grep my-branch
git branch my-branch <sha-from-reflog>

Show with timestamps

git reflog --date=iso

Make sure HEAD's reflog is enabled (it is, by default)

git config core.logAllRefUpdates true

🎓 Recommendations

Before any reset --hard, rebase, or filter-branch: note git rev-parse HEAD. Belt and braces.
Leave core.logAllRefUpdates = true (the default for non-bare repos). Disabling it to save bytes is penny-wise, pound-foolish.
Reflog is local. It does not push, fetch, or replicate. Don't expect a teammate's reflog to save you.

🪤 Common pitfalls

Bare repos have core.logAllRefUpdates = false by default — no reflog, no safety net on the server.
git gc prunes expired reflog entries and then unreachable objects. After 90 days, that emergency commit may genuinely be gone.
HEAD@{2} and master@{2} are different — @{N} means the Nth prior position of that specific ref, not the Nth global reflog entry.

🔗 Related modules

📝 Quiz

Hit each option, then Check answers. Score is recorded; Next is always open.