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Comment by rjtobin | Hacker News Reader

Some other Git features that I find super useful, which past colleagues of mine haven't known about (which maybe suggests they are not universally known).

git rev-parse branch-name: gets the hash of a branch name, useful for verifying two branches are at the same place (so "git rev-parse HEAD" gets the current hash)

The ^ and ~ notations for navigating commits: my_branch^ points to the commit 1 before my_branch, and can be repeated multiple times, ie. my_branch^^^ to get the commit 3 from the top. Likewise the tilda notation allows one to jump a fixed number of commits up: my_branch~10 is the commit 10 above my_branch.

git rebase -i HEAD~10: interactively rebase the last 10 commits. Easy way to re-order, squash, drop, and/or edit the commit messages of recent history in a single git command.

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This one is interesting, because if I recall correctly, if you are using the single symbol they more or less mean the same thing. You can do ~~~ or ^^^ and get to the same spot

The difference is in their numerical notion. ~N means go to my Nth first parent. Where ^N means my Nth parent, which is really only valuable/useful on merge commits (Or more specifically octopus merges that merge more than two commits)

This is why ~ and ^ in the single form mean the same thing.

So, in one mental model of the DAG you can think of ^ as horizontal navigation (Right) and ~ as vertical (Down)

Oh cool! That's good to know. Sadly too late to edit my original message, but have upvoted yours so people won't learn from my errors :)

> git rev-parse branch-name: gets the hash of a branch name, useful for verifying two branches are at the same place

I believe the same thing can be done by running git log --oneline -n1 branch-name (though you will also get the commit message title in addition to the sha).

> my_branch^ points to the commit 1 before my_branch, and can be repeated multiple times, ie. my_branch^^^ to get the commit 3 from the top.

The ^ notation only references the first parent of the commit. You would have to do something like commitish^2 to reference the second parent (though this would only be an issue for merge commits or any commit that has more than one parent).

My god, we have to use git in school and no one knows about rebasing. A group member made commits with profanity in messages (ha-ha, so funny, now how about some useful messages though?) and it turned out at the end we had to submit the repo. Everyone was panicking until I told them I could change the message in literally half a minute.

Rebasing cleans up my commits so much. It is nice being able to have a chain of nice, logical commits even in the middle of a hairy refactor.

A couple of other ways to see if two branches are the same or not

  git diff branch1 branch2

git show displays any additional branches that are the same.

  $ git show -q
  commit 2ee0fd3e2717a352b6ded617184be280cb55e78c (HEAD -> master, foo)
  ...

Just learned git rebase -i last week. Added tip: git rebase --abort at any point in the process if you're not sure if you did the right thing.

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