Tutorial: GIT and GitHubMixed Reset (Default) - 2020

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git Reset

Git Reset:

Soft
1. Moves the HEAD
2. git reset --soft 4ff01e7
Mixed (default reset)
1. Changes HEAD and Staging index
2. git reset --mixed 4ff01e7
Hard
1. Dangerous
2. Reverts completely back to commit
3. git reset --hard 4ff01e7

Mixed Reset (Default)

Before the git reset:

After the git reset:

The HEAD is going to move, but instead of "v3" coming down and being our staging index version, "v2" is going to come down and becomes our staging version. That means nothing in our stage because the one in our stage will match up and link with the one in our repository. In other words, we're going to have nothing to commit.

The only change is in our working directory. So, what this default (or mixed) reset does is to make sure our staging index is the same as the HEAD in our repository.

Picture credit: Learn Git 20: The Mixed Reset

We have 3 files in repository: Appendix, Book1, Introduction.

k@laptop:~/GitDemo$ ls 
Appendix.rtf		Book1.rtf		Introduction.rtf

The 'Book1' file looks lie this:

Annabel Lee
BY EDGAR ALLAN POE 1809-1849
Published in 1849

Update A
Update B
Update C

Here is the history of our commits so far:

k@laptop:~/GitDemo$ git log --oneline
4c8acfd make one commit instead of three commits
8bdf380 modified the year of death & added published
3ed224f added published year
691923c added birth and death
d5e38ad adde book title
e1ec728 Book2->Introduction
8d7d7f1 renamed Book3 as Appendix
7a4caa8 deleted OldBook
b28c909 Initial commits - Book1 Book2 Book3 OldBook

The most recent commit is the one for adding three lines of updates (Update A, Update B, and Update C) at one shot. Now we changed our plan, and we want to backup to before the recent commit. Because the git reset --mixed is the default, we can just use git reset instead:

k@laptop:~/GitDemo$ git reset 8bdf380
Unstaged changes after reset:
M	Book1.rtf

We can look at the status:

k@laptop:~/GitDemo$ git status
On branch master
Changes not staged for commit:
  (use "git add ..." to update what will be committed)
  (use "git checkout -- ..." to discard changes in working directory)

	modified:   Book1.rtf

no changes added to commit (use "git add" and/or "git commit -a")

As shown in the picture at the beginning, the HEAD has been moved and pointing to the previous snapshot, the only difference is the 'Book1' in working directory. Note that it has the three lines of update which is the last commit:

Annabel Lee
BY EDGAR ALLAN POE 1809-1849
Published in 1849

Update A
Update B
Update C

We do not see the difference between staging-repo and between working directory-the last commit:

k@laptop:~/GitDemo$ git diff --staged
k@laptop:~/GitDemo$ git diff --cached

Now we want to delete "Update B" and "Update C", then commit only "Update A" line. So, the modified 'Book1' looks like this:

Annabel Lee
BY EDGAR ALLAN POE 1809-1849
Published in 1849

Update A

Status check after the edit:

k@laptop:~/GitDemo$ git status
On branch master
Changes not staged for commit:
  (use "git add ..." to update what will be committed)
  (use "git checkout -- ..." to discard changes in working directory)

	modified:   Book1.rtf

no changes added to commit (use "git add" and/or "git commit -a")

Add and commit:

k@laptop:~/GitDemo$ git add Book1.rtf

k@laptop:~/GitDemo$ git commit -m "Adding only Update A"
[master 08eb088] Adding only Update A
 1 file changed, 2 insertions(+), 1 deletion(-)

k@laptop:~/GitDemo$ git status
On branch master
nothing to commit, working directory clean

k@laptop:~/GitDemo$ git log --oneline
08eb088 Adding only Update A
8bdf380 modified the year of death & added published
3ed224f added published year
691923c added birth and death
d5e38ad adde book title
e1ec728 Book2->Introduction
8d7d7f1 renamed Book3 as Appendix
7a4caa8 deleted OldBook
b28c909 Initial commits - Book1 Book2 Book3 OldBook