Explain git log code

What this git log sample shows

commits

Each entry is one commit, newest first: its full hash, who wrote it, when, and the message. --oneline keeps only a short hash and the first line, so 6dd93ddd5276... became 6dd93dd. git log -1 --format='%h %an %ad %s' --date=short printed 6dd93dd Sam Lee 2026-11-04 Merge branch 'discount'.

merges

A merge commit has two parents, and the Merge: line lists them: b0b26af is the commit main was on, and 6788b88 is the branch's last commit. HEAD^1 named Say how to run it and HEAD^2 named Let total take a discount.

the graph

In --graph, each * is a commit and the lines show history splitting and joining: |/ is where discount branched off after Add cart total, and |\ is where the merge brought it back. --decorate adds the names that point at a commit: HEAD -> main is the branch you're on, tag: v1.0 a tag and (discount) the branch.

filtering

git log --author=Ana listed only Let total take a discount, and git log -- cart.js only the 2 commits that changed that file. git log discount..main lists what main has that discount doesn't: the merge and Say how to run it. main..discount printed nothing, because the branch is fully merged.

Good to know

• Made with git 2.55.0 in a test repo with fixed names and dates, so the same commands give the same hashes. The graph's |\ and |/ lines end in spaces in git's output; they're trimmed here.
• git log -p adds each commit's diff, and --stat a summary: for Ana's commit, cart.js | 4 ++-- and 1 file changed, 2 insertions(+), 2 deletions(-).
• A long log opens in a pager, less unless you set another, so it can look stuck: press q to get back to the prompt.

Watch out: A plain git log sorts every merged branch's commits into one list by date, so it isn't the order work landed on main: git log --oneline listed the merge, Say how to run it, then Ana's Let total take a discount from the branch, then Add cart total. git log --first-parent follows only main's side of each merge and listed 4 commits, the merge, Say how to run it, Add cart total and Start the shop, without Ana's.