git merge-base
    ???

grep -r'<<<<' *
    search for all the merge conflict markers


git config --global merge.tool
git config --global diff.tool

git merge
    --no-ff
        do not do a fast-forward (for one-commit merges)
    --ff-only
        only do a fast-forward

git checkout <to-branch>
git merge <from-branch>
git merge <from-branch> <to-branch>
    one-line cmd


git merge --no-ff <issue>-<desc>
-//- no fast-forward

-s <merge-strategy>
    recursive
        the default one
    subtree

-X subtree=vendor/plugins/demo
    ???

--squash
    for squash, it does not finalize the commit (you may adjust it later)


merge-drivers:
https://medium.com/@porteneuve/how-to-make-git-preserve-specific-files-while-merging-18c92343826b

git config --global merge.ours.driver /bin/true

.gitattributes
email.json merge=ours


conf:

merge.ff
http://stackoverflow.com/questions/2500296/can-i-make-fast-forwarding-be-off-by-default-in-git
git config [--global] --add merge.ff false

pull.ff