lab 19 Amending Commits

Goals

Learn how to amend an existing commit

Change the program then commit

Add an author comment to the program.

hello.rb

# Default is World
# Author: Jim Weirich
name = ARGV.first || "World"

puts "Hello, #{name}!"

Execute:

git add hello.rb
git commit -m "Add an author comment"

Oops, Should have an Email

After you make the commit, you realize that any good author comment should have an email included. Update the hello program to include an email.

hello.rb

# Default is World
# Author: Jim Weirich (jim@somewhere.com)
name = ARGV.first || "World"

puts "Hello, #{name}!"

Amend the Previous Commit

We really don’t want a separate commit for just the email. Let’s amend the previous commit to include the email change.

Execute:

git add hello.rb
git commit --amend -m "Add an author/email comment"

Output:

$ git add hello.rb
$ git commit --amend -m "Add an author/email comment"
[master e1e08fd] Add an author/email comment
 Date: Fri Sep 28 08:58:09 2018 -0700
 1 file changed, 2 insertions(+), 1 deletion(-)

Review the History

Execute:

git hist

Output:

$ git hist
* e1e08fd 2018-09-28 | Add an author/email comment (HEAD -> master) [Jim Weirich]
* 7bf0bf1 2018-09-28 | Added a comment (tag: v1) [Jim Weirich]
* 9cf3f21 2018-09-28 | Added a default value (tag: v1-beta) [Jim Weirich]
* 94e1b8b 2018-09-28 | Using ARGV [Jim Weirich]
* f656098 2018-09-28 | First Commit [Jim Weirich]

We can see the original “author” commit is now gone, and it is replaced by the “author/email” commit. You can achieve the same effect by resetting the branch back one commit and then recommitting the new changes.