Forgot to branch in git, need to move changes from master [duplicate]

Question

I eagerly ducked into code mode and modified some files, but neglected to branch from master first. The mods aren't so extensive that I can't redo them, but what's a good way of taking my (so far, uncommitted) changes in master and migrating them to a new branch, leaving master untouched in the end?

Answer 1

If not yet committed anywhere (git status shows a bunch of stuff modified, it's OK if it's "git add"-ed too):

$ git checkout -b newbranch 

Despite the name checkout this usage (with -b) does not check anything out. The -b flag says "create a new branch", so git creates the branch-name and makes it correspond to the current HEAD commit. Then it makes HEAD point to the new branch, and stops there.

Your next commit is therefore on newbranch, which has as its parent commit, the commit you were on when you started modifying files. So assuming you were on master, and you had these commits:

A - B - C       <-- HEAD=master 

the checkout -b makes this read:

A - B - C       <-- master, HEAD=newbranch 

and a later commit adds a new commit D:

A - B - C       <-- master           \             D   <-- newbranch