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1. Create a branch with name sketches:

   No Format
   $ git branch sketches

2. View the list of branches:

   No Format
   $ git branch * master sketches

   The star reveals that you are still on the old master branch.

3. Switch to the new branch:

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   $ git checkout sketches Switched to branch 'sketches' $ git branch master * sketches

   It is also possible to create a branch and switch immediately to it using the option -b of git checkout.

4. Download and add the new file examples.txt:

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   $ git add examples.txt $ git commit -m "wrote first examples" [sketches cd63135] wrote first examples 1 files changed, 20 insertions(+), 0 deletions(-) create mode 100644 examples.txt

   Inspecting the commit graph with gitk (or another graphical viewer) you see that the sketches branch now has three commits, while master is still at the second commit.

5. Merging the sketches branch into master means that all changes that have been made in sketches are also applied to master. In order to perform this merge, we have to check out the master branch first:

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   $ git checkout master Switched to branch 'master' $ git merge sketches Updating 52e2d49..cd63135 Fast-forward examples.txt | 20 ++++++++++++++++++++ 1 files changed, 20 insertions(+), 0 deletions(-) create mode 100644 examples.txt

   This was a fast-forward merge: since the master branch was completely contained in the sketches branch, the merge could be done by simply changing the head pointer of master to be the same as the head of sketches.

6. Now add the line "see some examples in 'examples.txt'" to the file notes.txt and commit this change in the current branch:

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   $ git add notes.txt $ git commit -m "added reference to the new examples" [master a5e244f] added reference to the new examples 1 files changed, 2 insertions(+), 1 deletions(-)

7. Switch back to the sketches branch and modify it as shown below. Note that the checkout command modifies your working copy, hence you have to update your text editor's content if you opened one of the files.

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   $ git checkout sketches Switched to branch 'sketches'

   Add the line "Move one step left:" and write followed by an accordingly updated version of the tape with tape head in the at the end of the file examples.txt, then commit.

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   $ git add examples.txt $ git commit -m "added another example" [sketches 55a9cb1] added another example 1 files changed, 5 insertions(+), 0 deletions(-)

   Now your two branches have diverged, which means that they cannot be fast-forwarded anymore.

8. Merge the master branch into sketches:

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   $ git merge master Merge made by recursive. notes.txt | 3 ++- 1 files changed, 2 insertions(+), 1 deletions(-)

   Using gitk you can see that a new commit was created that has two parent commits. Such a commit is called merge commit and is done automatically when a non-fast-forward merge is applied. See how both the change to notes.txt done in the master branch and the change to examples.txt done in the sketches branch are now contained in the repository state that results from the merge.

9. Add a commit in each of the two branches using the commands you have already learned.
   
   1. Check out master.

   2. Insert the following line after line 4 of notes.txt:

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      nopanel true
      * The finite state machine has an initial state and one or more final states

   3. Commit the change of notes.txt.
   4. Check out sketches (make sure to refresh your text editor so that notes.txt is reset to its previous state, without the change made above).

   5. Insert the following line after line 4 of notes.txt:

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      nopanel true
      * Each state transition can trigger head movement and data read/write

   6. Commit the change of notes.txt.

10. Merge the master branch into the current branch (sketches):

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    $ git merge master Auto-merging notes.txt CONFLICT (content): Merge conflict in notes.txt Automatic merge failed; fix conflicts and then commit the result.

    As expected, the branches could not be merged automatically, since both branches modified the same line in the same file.

11. Use the status command to see the list of affected files:

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    $ git status # On branch sketches # Unmerged paths: # (use "git add/rm <file>..." as appropriate to mark resolution) # # both modified: notes.txt # no changes added to commit (use "git add" and/or "git commit -a")

12. The modified notes.txt should now contain the following text:

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    nopanel true
    <<<<<<< HEAD * Each state transition can trigger head movement and data read/write ======= * The finite state machine has an initial state and one or more final states >>>>>>> master

    The upper line is the one committed to sketches, while the lower line was committed to master. You have to resolve the conflict by editing the file. In this case the conflict is resolved by keeping both lines in arbitrary order, that means you should just remove the conflict markers (lines 5, 7, and 9 in notes.txt).

13. Use the add command to mark notes.txt as resolved. Entering git commit without a message will open a text editor with an automatically created commit message. Just close the editor, and the merge commit is completed:

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    $ git commit [sketches 21d5ddb] Merge branch 'master' into sketches $ git show 21d5ddb commit 21d5ddbbcba4e36464653a2a550dbf595ead921f Merge: 17f75c7 8af2d50 Author: Miro Spoenemann <msp@informatik.uni-kiel.de> Date: Tue Oct 16 10:44:09 2012 +0200 Merge branch 'master' into sketches Conflicts: notes.txt diff --cc notes.txt index 8f72873,bb81298..ba94a08 --- a/notes.txt +++ b/notes.txt @@@ -2,6 -2,6 +2,7 @@@ * Tape head can read or write data * Tape head can move left or right * The head is controlled by a finite state machine + * Each state transition can trigger head movement and data read/write + * The finite state machine has an initial state and one or more final states see some examples in 'examples.txt'

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