Version Control With Git: Local Operations
Automatically merging changes with git
Yesterday we showed you how you could use version control to record the history of changes to files and rewind files to their old revisions.
Today we will cover combining different sets of changes (that may have been made at different times, by different people, or for different purposes.) When it's possible to apply both your changes and your collaborator's changes without the two interfering with each other, git can combine both sets of changes automatically.
Let's go back to our repository– cd ~/my_first_repository And admire our work from yesterday:
git log --oneline
git branch : Listing, Creating, and Deleting Branches
Branches are pointers to a version of a repository that can be edited and version controlled in parallel. They are useful for pursuing various implementations experimentally or maintaining a stable core while developing separate sections of a code base.
Without an argument, the branch command lists the branches that exist in your repository.
$ git branch
* master
The master branch is created when the repository is initialized. With an argument, the branch command creates a new branch with the given name.
$ git branch experimental
$ git branch
* master
experimental
To delete a branch, use the -d flag.
$ git branch -d experimental
$ git branch
* master
git checkout : Switching Between Branches, Abandoning Local Changes
The git checkout command allows context switching between branches as well as abandoning local changes.
To switch between branches, try
$ git branch newbranch
$ git checkout newbranch
$ git branch
How can you tell we've switched between branches? When we used the branch command before there was an asterisk next to the master branch. That's because the asterisk indicates which branch you're currently in.
git merge : Merging Branches
At some point, the experimental branch may be ready to become part of the core or two testing branches may be ready to be combined for further integration testing. The method for combining the changes in two parallel branches is the merge command.
Exercise : Create and Merge Branches
Step 1 : Create two new branches and list them
$ git branch first
$ git branch second
Step 2 : Make changes in each new branch and commit them.
$ git checkout first
Switched to branch 'first'
$ touch firstnewfile
$ git add firstnewfile
$ git commit -am "Added firstnewfile to the first branch."
[first 68eba44] Added firstnewfile to first branch.
0 files changed, 0 insertions(+), 0 deletions(-)
create mode 100644 firstnewfile
$ git checkout second
Switched to branch 'second'
$ touch secondnewfile
$ git add secondnewfile
$ git commit -am "Added secondnewfile to the second branch."
[second 45dd34c] Added secondnewfile to the second branch.
0 files changed, 0 insertions(+), 0 deletions(-)
create mode 100644 secondnewfile
Step 3 : Merge the two branches into the core
$ git checkout first
Switched to branch 'first'
$ git merge second
Merge made by recursive.
0 files changed, 0 insertions(+), 0 deletions(-)
create mode 100644 secondnewfile
$ git checkout master
Switched to branch 'master'
$ git merge first
Updating 1863aef..ce7e4b5
Fast-forward
0 files changed, 0 insertions(+), 0 deletions(-)
create mode 100644 firstnewfile
create mode 100644 secondnewfile