Initialize Git repository, CHDIR into its top-level directory

% git init branching
Initialized empty Git repository in /home/drbitboy/tmp/branching/.git/

% cd branching

Create new python script that prints Greatest Generation members

% vi family_.py

% cat family_.py
"""
Frank Conley
Marilyn Bush
John Carcich
Catherine Rerecich
"""

if "__main__" == __name__:
  for fammember in __doc__.strip().split('\n'):
    print(fammember)

Exercise that script

% python family_.py
Frank Conley
Marilyn Bush
John Carcich
Catherine Rerecich

Add and commit that script to this current master branch as the initial commit

% git add family_.py

% git commit -m initial.commit
[master (root-commit) f27ab44] initial.commit
 1 file changed, 10 insertions(+)
 create mode 100644 family_.py

% git log
commit f27ab44dbcfd06a3f08a1f27611e08baf0e85a12 (HEAD -> master)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:27:55 2025 -0400

    initial.commit

Make, and checkout, a new branch that is a copy of that current master branch

New branch name is next_gen

% git checkout -b next_gen
Switched to a new branch 'next_gen'

Show branches and log

Asterisk is next to HEAD (current checked-out branch, next_gen)

% git branch
  master
* next_gen

% git log
commit f27ab44dbcfd06a3f08a1f27611e08baf0e85a12 (HEAD -> next_gen, master)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:27:55 2025 -0400

    initial.commit

Edit script to add Boomers, show edited content, run script

% vi family_.py

% cat family_.py
"""
Frank Conley
Marilyn Bush
John Carcich
Catherine Rerecich
Jessica Conley
Brian Carcich
"""

if "__main__" == __name__:
  for fammember in __doc__.strip().split('\n'):
    print(fammember)

% python family_.py
Frank Conley
Marilyn Bush
John Carcich
Catherine Rerecich
Jessica Conley
Brian Carcich

Add, and then commit, updated script to current next_gen branch, then show log

• Note that only the next_gen name is associated with the new commit hash 03c0622...
  • The master branch is unchanged
    • The branch name master is still associated with commit hash f27ab44...

% git add family_.py

% git commit -m "1956 additions"
[next_gen 03c0622] 1956 additions
 1 file changed, 2 insertions(+)

% git log
commit 03c06228c8cd280ebb94cc49df6e8de1faea1122 (HEAD -> next_gen)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:29:06 2025 -0400

    1956 additions

commit f27ab44dbcfd06a3f08a1f27611e08baf0e85a12 (master)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:27:55 2025 -0400

    initial.commit

Edit script to add Millenials, run script

% vi family_.py

% python family_.py
Frank Conley
Marilyn Bush
John Carcich
Catherine Rerecich
Jessica Conley
Brian Carcich
Gemma Carcich
Benjamin Anible
Benjamin Carcich
Laura Lohberger
Daniel Carcich
Alexandra Carcich

Add, and then commit, updated script to current next_gen branch, then show log

% git add family_.py

% git commit -m "1980s additions"
[next_gen cbfb227] 1980s additions
 1 file changed, 6 insertions(+)

% git log
commit cbfb227431a4523dc4d40447315241aec926329b (HEAD -> next_gen)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:30:41 2025 -0400

    1980s additions

commit 03c06228c8cd280ebb94cc49df6e8de1faea1122
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:29:06 2025 -0400

    1956 additions

commit f27ab44dbcfd06a3f08a1f27611e08baf0e85a12 (master)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:27:55 2025 -0400

    initial.commit

Edit script to add Kids, run script

% vi family_.py

% python family_.py
Frank Conley
Marilyn Bush
John Carcich
Catherine Rerecich
Jessica Conley
Brian Carcich
Gemma Carcich
Benjamin Anible
Benjamin Carcich
Laura Lohberger
Daniel Carcich
Alexandra Carcich
Georgi Carcich
Violet Carcich
Naomi Carcich

Add, and then commit, updated script to current next_gen branch, then show log

% git add family_.py

% git commit -m "great grandchildren"
[next_gen 73ebd47] great grandchildren
 1 file changed, 3 insertions(+)

% git log
commit 73ebd470a4108c0e0b37a2db3b65a4cf1cb5da95 (HEAD -> next_gen)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:31:51 2025 -0400

    great grandchildren

commit cbfb227431a4523dc4d40447315241aec926329b
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:30:41 2025 -0400

    1980s additions

commit 03c06228c8cd280ebb94cc49df6e8de1faea1122
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:29:06 2025 -0400

    1956 additions

commit f27ab44dbcfd06a3f08a1f27611e08baf0e85a12 (master)
Author: Brian Carcich <briantcarcich@gmail.com>
Date:   Sun Jun 15 08:27:55 2025 -0400

    initial.commit

Show --oneline --graph log

% git log --all --decorate --color --oneline --graph
* 73ebd47 (HEAD -> next_gen) great grandchildren
* cbfb227 1980s additions
* 03c0622 1956 additions
* f27ab44 (master) initial.commit

Create, add, and commit readme to the next_gen branch

% vi README.md

% git add README.md

% git commit -m add.readme

A different person makes a small edit to the master branch

• Note that the master branch initially is still the f27ab44 initial.commit

% git checkout master
% vi family_.py
$ git add family_.py
$ git commit -m rename.variable

Here is the difference between that f27ab44 initial.commit and the current master branch

% git diff f27ab44 master
diff --git a/family_.py b/family_.py
index e8bce82..a98ea25 100644
--- a/family_.py
+++ b/family_.py
@@ -6,5 +6,5 @@ Catherine Rerecich
 """

 if "__main__" == __name__:
-  for fammember in __doc__.strip().split('\n'):
-    print(fammember)
+  for family_member in __doc__.strip().split('\n'):
+    print(family_member)

Show --oneline --graph log of the current state

• Note that there are two commit sequences starting from f27ab44 initial.commit
  • The left (vertical) sequence leads to commit 24b6d15 branch next_gen
  • The right sequence leads to commit bf19ace branch master

% git log --all --decorate --color --oneline --graph
* 24b6d15 (origin/next_gen, next_gen) add.readme
* 73ebd47 great grandchildren
* cbfb227 1980s additions
* 03c0622 1956 additions
| * bf19ace (HEAD -> master, origin/master) rename.variable
|/
* f27ab44 initial.commit

Checkout master branch, then merge next_gen branch into it

% git checkout master
Switched to branch 'master'
Your branch is up to date with 'origin/master'.


% git merge next_gen
Auto-merging family_.py
Merge made by the 'recursive' strategy.
 README.md  | 384 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 family_.py |  11 +++
 2 files changed, 395 insertions(+)
 create mode 100644 README.md

Show --oneline --graph log

• Graph display illustrates how branches have been merged

% git log --all --decorate --color --oneline --graph
*   96c62fb (HEAD -> master) Merge branch 'next_gen' into master
|\
| * a15b3d4 (origin/next_gen, next_gen) add.readme
| * 73ebd47 great grandchildren
| * cbfb227 1980s additions
| * 03c0622 1956 additions
* | bf19ace (origin/master) rename.variable
|/
* f27ab44 initial.commit