[Vm-dev] reattaching a detatched git head...

Ben Coman btc at openinworld.com
Wed Oct 12 17:22:08 UTC 2016

On Wed, Oct 12, 2016 at 8:20 AM, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> I'm stuck.  Don't know how I detached from the master.

Maybe a good opportunity to peek under the hood to understand how it
may have happened.   I'm freshly enlightened from reading around the
subject past couple of hours and I picked a few of the best

A programming analogy providing an interesting alternative to most articles...

coupled with a visual presentation...

and bringing it together (with a comparison to Mercurial)...

> I'm seeing this:
> You are in 'detached HEAD' state. You can look around, make experimental
> changes and commit them, and you can discard any commits you make in this
> state without impacting any branches by performing another checkout.
> If you want to create a new branch to retain commits you create, you may
> do so (now or later) by using -b with the checkout command again. Example:
>   git checkout -b <new-branch-name>
> HEAD is now at ed4a499... CogVM source as per VMMaker.oscog-eem.1958
> I want to make this the new master, and then add a commit.  I'm stuck.  Git mavens, help please.

At  https://github.com/OpenSmalltalk/opensmalltalk-vm/network
I see that ed4a499 at this moment is a couple of commits back from the
tip of the Cog branch around the 12 Oct
but no merges after that, so without more background info I'll assume
for discussion a hypothetical scenario where you wanted to throw away
some local commits and in svn you would use 'checkout' (??) so you
used something like 'git checkout HEAD~1' instead of  'git reset
HEAD~1' to move to branch to a previous commit??   The difference is
demostrated here... (use left/right arrow keys to navigate)

John's example seems a common way to deal with a detached HEAD. Since
the commit was given to you actually could probably do...
  $ git checkout Cog
  $ git merge ed4a499
except that wouldn't help the hypothetical scenario above if the Cog
branch had moved forward with commits you wanted to kill.  If these
were only local changes, then 'reset' is probably what you need, but
if the commits had already been made public, 'revert' may be more

cheers -ben

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