Git merge branch into master

Conflicts are going to happen if both branches have changes to the files. This is a good thing. Keeping your branches up-to-date with each other will prevent some of them . However over all, conflicts are not bad. The rebase option can also prevent many of them from happening.

git merge branch_1

If you are on master, merging will bring the changes as you expect.

http://www.kernel.org/pub/software/scm/git/docs/git-merge.html

You could also

git rebase branch_1

This will take the changes from branch_1 and append them to master without a merge commit.

http://www.kernel.org/pub/software/scm/git/docs/git-rebase.html

Maybe you should not merge?

1. Checkout branch_1
2. Rebase master changes into branch_1
3. Fix any errors that might have occured after testing your code
4. Checkout master
5. Rebase branch_1 changes into master

or in code:

git checkout branch_1
git rebase master
(...)
git checkout master
git rebase branch_1

This also gives you the opportunity to squash several commits into one, if you want to make your changesets more dense, and prevents these annoying merge-commits in your history.