Merging 2 branches together in GIT

Question

I've only just started to use GIT and think its wonderful, however I'm a little confused over what the merge command does.

Let us say we have a working project in the branch "A".

I go home and make changes to this branch and save it as "B". Another programmer makes changes to "A" and saves it as "C".

Is there a way to merge the two branches "B" and "C" together, then commit the changes as a new branch, say "D"?

Or am missing the point of 'merge'?

Answer 1

merge is used to bring two (or more) branches together.

a little example:

# on branch A:
# create new branch B
$ git checkout -b B
# hack hack
$ git commit -am "commit on branch B"

# create new branch C from A
$ git checkout -b C A
# hack hack
$ git commit -am "commit on branch C"

# go back to branch A
$ git checkout A
# hack hack
$ git commit -am "commit on branch A"

so now there are three separate branches (namely A B and C) with different heads

to get the changes from B and C back to A, checkout A (already done in this example) and then use the merge command:

# create an octopus merge
$ git merge B C

your history will then look something like this:

…-o-o-x-------A
      |\     /|
      | B---/ |
       \     /
        C---/

if you want to merge across repository/computer borders, have a look at git pull command, e.g. from the pc with branch A (this example will create two new commits):

# pull branch B
$ git pull ssh://host/… B
# pull branch C
$ git pull ssh://host/… C