Git Notes

This will be a continual work in progress and a testament that I should have made this post over a decade ago.

Dedicated fast-forward merge post of mine.

Reminders: the “index” is what holds staged changes. Useful site for undoing/recovering stuff: https://dangitgit.com .

This post and a lot advice and help for git on the internet assumes the command line.  That is because the git command line is same for everyone and easy to give precise instructions.  But really you should try to do as much as possible inside a nice git gui, possibly your IDE or SourceTree.  A nice git gui makes it easy to go from "I want to ..." to "I did it" by exploring menus and possibly right clicking items instead of looking up weird commands and syntax that you will soon forget.  A nice git gui also makes it much easier to see and understand your current repo state and its history.

Git Fast-Forward

Fast-forward merges have properties that are tightly tied together (basically they are equivalent)...

• A fast-forward merge is exactly the sort of merge that doesn't create a merge commit (assuming that you aren't doing destructive operations on commit history).
• A fast-forward merge is exactly the sort of merge that just updates the branch pointer. (Remember that `git pull` first does a `fetch` to get the remote commits before the merge happens, so a merge "just updating the branch pointer" can involve commits that didn't exist locally until the fetch.)
  
• A merge is fast-forwardable exactly when the source commit history is a superset of the destination branch commit history.
• A merge is fast-forwardable exactly when the destination commit is an ancestor of the source commit.