I'm apparently terrible at using git, despite my best attempts to understand it.
From kernel.org for git push
:
-u
–set-upstream
For every branch that is up to date or successfully pushed, add upstream (tracking) reference, used by argument-less git-pull(1) and other commands. For more information, see
branch.<name>.merge
in git-config(1).
Here's branch.<name>.merge
from git config
:
branch.<name>.merge
Defines, together with
branch.<name>.remote
, the upstream branch for the given branch. It tells git fetch/git pull which branch to merge and can also affect git push (see push.default). When in branch<name>
, it tells git fetch the default refspec to be marked for merging in FETCH_HEAD. The value is handled like the remote part of a refspec, and must match a ref which is fetched from the remote given by"branch.<name>.remote"
. The merge information is used by git pull (which at first calls git fetch) to lookup the default branch for merging. Without this option, git pull defaults to merge the first refspec fetched. Specify multiple values to get an octopus merge. If you wish to setup git pull so that it merges into<name>
from another branch in the local repository, you can pointbranch.<name>.merge
to the desired branch, and use the special setting . (a period) forbranch.<name>.remote
.
I successfully set up a remote repository with github, and I successfully pushed my first commit to it with:
git push -u origin master
Then, I unwittingly successfully pushed my second commit to my remote repository using:
git commit -m '[...]'
However, incorrectly thinking I would have to push again to origin
from master
, I ran:
# note: no -u
git push origin master
What did that do? It didn't seem to have any effect at all. Did I "undo" git push -u origin master
?
Best Answer
The key is "argument-less git-pull". When you do a
git pull
from a branch, without specifying a source remote or branch, git looks at thebranch.<name>.merge
setting to know where to pull from.git push -u
sets this information for the branch you're pushing.To see the difference, let's use a new empty branch:
First, we push without
-u
:Now if we add
-u
:Note that tracking information has been set up so that
git pull
works as expected without specifying the remote or branch.Update: Bonus tips:
git pull
this setting also affects default behavior ofgit push
. If you get in the habit of using-u
to capture the remote branch you intend to track, I recommend setting yourpush.default
config value toupstream
.git push -u <remote> HEAD
will push the current branch to a branch of the same name on<remote>
(and also set up tracking so you can dogit push
after that).