git reflog

Reflog answers "where was HEAD five minutes ago," which is why it lets you recover almost any state you have been in recently.

Basic form

git reflog

# a1b2c3d HEAD@{0}: reset: moving to HEAD~3

# 4d5e6f7 HEAD@{1}: commit: feat: add login

# 8a9b0c1 HEAD@{2}: commit: docs: update README

# ...

Each line is the state of HEAD at the moment of an operation. Newer entries appear at the top. Columns: SHA, syntactic ref, reason.

The most common scenario

After an accidental reset:

git reset --hard HEAD~10    # oops, wrong target

git reflog                  # first line shows the SHA after the reset,

                            # second line shows the SHA before it

git reset --hard HEAD@{1}   # return to the state before the reset

Or directly by SHA:

git reset --hard 4d5e6f7    # SHA from reflog

What reflog covers

Reflog records nearly every operation that moves HEAD:

• commit, commit --amend
• checkout/switch between branches
• merge, rebase (a whole series of entries)
• reset --hard, reset --soft
• pull (moves HEAD via its merge/rebase; a plain fetch does not touch HEAD, it only updates refs/remotes/*, which have their own separate reflog)
• Branch creation/deletion via branch -d/-D (the last position of that branch)

Each branch also has its own reflog:

git reflog show feature        # history of positions for branch feature

git reflog show HEAD           # equivalent to git reflog

When reflog will not help

• Uncommitted changes. If a file was only in the working tree or the index and was never committed, reflog cannot see it. Reflog tracks commits only.
• Untracked files deleted with git clean -fd. Same case.
• Other machines. Reflog is local. Your colleague has their own reflog; your actions are not in it.
• Older than the reflog retention period. The default is 90 days for reachable objects and 30 days for unreachable ones. After that, git gc cleans them up.
• After an explicit git gc --prune=now + git reflog expire. These commands erase history immediately.

Adjusting retention periods

If you work with very long-lived branches or want a longer safety net:

git config --global gc.reflogExpire "180 days"

git config --global gc.reflogExpireUnreachable "90 days"

Or to disable reflog entirely (rarely needed, saves disk space):

git config --global gc.reflogExpire 0

git config --global gc.reflogExpireUnreachable 0

Pitfalls

• HEAD@{N} is not HEAD~N. The first is the N-th entry in the reflog (by time). The second is the N-th ancestor commit (by graph). They are different things.
• HEAD@{yesterday}, HEAD@{2.hours.ago} are time-based syntax. Handy: git diff HEAD@{1.week.ago} HEAD.
• Reflog is stored in .git/logs/ as plain text files. You can read them directly, but git reflog is more convenient.
• On a freshly cloned repository the reflog is empty. History lives in the commits, not in the reflog. Reflog records only local HEAD movements, and a new clone has none yet.