Advanced Git
git restore
If you can't undo changes in your file editor, Git offers an option to do so. In the output of the git status command, you'll see the message suggesting you use git restore -- <file>... to discard changes in your working directory. You can use this command to undo changes as shown below:
git restore -- index.html
git reset
The git reset command is used to undo commits and move your current branch pointer to a different commit. It can change the commit history while preserving or discarding changes in your working directory.
To reset to the commit before the latest one while keeping your changes staged, use:
git reset --soft HEAD~1
The HEAD~1 flag tells Git to move your current branch back by one commit, effectively removing the last commit. The --soft flag ensures that any changes made since that commit remain in the staging area.
If you want to completely discard changes made since the specified commit, use:
git reset --hard HEAD~1
Sample output:
HEAD is now at 2dca417 Merge pull request #1 from cloudacademy/feature/update-title
The --hard flag will delete all changes made since the specified commit, including any new files. Be cautious when using hard resets, as they are one of the few actions in Git that cannot be easily undone.
git stash
Stashing means placing all your uncommited changes on a stack so they are safe for later access. Note that when you run this, your uncommited change will be discarded and the file will revert to its original state.
Some common commands:
-
Saves local modifications and reverts working directory to match the HEAD commit.
git stash -
Lists all the stashes you have saved.
git stash list -
Reappliy the most recently stashed changes to your working directory. The stash remains in the stash list after applying.
git stash apply -
Reappliy a specific stash identified by its index (e.g., stash@0 for the most recent stash).
git stash apply stash@{index} -
Remove the most recently stashed changes from the stash list.
git stash drop -
Remove a specific stash identified by its index.
git stash drop stash@{index} -
Reapply the most recently stashed changes and removes the stash from the stash list.
git stash pop -
Create a Stash with a Message.
git stash save "your message" -
Stash changes, including untracked files.
git stash -u -
Stash changes, including untracked and ignored files.
git stash -a
git rebase
Instead of merging branches, which creates a commit history that can include multiple merge commits, rebasing creates a linear, cleaner commit history. Note that rebasing will wipe out everything that is changed in the code.
Some common commands:
-
Rebase the current branch onto another branch.
git rebase <base-branch> -
Use the -i flag to start an interactive rebase.
git rebase -i <base-branch>
git log
The git log command displays a list of commits made to the repository.
git log
Sample output:
commit 2dca4178sdsdd86789as7ea157dsdsd67sdff3d6 (HEAD -> new_branch, origin/master, origin/HEAD, master)
Merge: ae05432 f2d9c95
Author: John Smith <johnsmith@gmail.com>
Date: Wed Nov 20 16:50:24 2019 -0600
Merge pull request
update title
commit f2d9c95f623c8d69193680732b69c21e50828914 (origin/feature/update-title)
Author: Matthew Martinez <johnsmith@gmail.com>
Date: Wed Nov 20 16:40:40 2019 -0600
update title
commit ae05432ea07eaf8e2d5232b6a40345f1bb33c9ac
Author: Ted Mosby <tedmosby@gmail.com>
Date: Tue Nov 19 15:31:36 2019 -0700
Initial commit
Using the --oneline flag provides a simple, summarized view:
git log --oneline
Sample output:
e7a1f6d Update README.md
b1c3e44 Add feature/update-title branch
f3d2a8b Initial commit
Each commit shows a short ID, branch names (e.g., master, origin/feature/update-title), and a commit message. Branches can be seen as pointers to specific commits, allowing you to track changes across different branches.
For a visual of branch history, add the --graph flag:
git log --oneline --graph
Sample output:
* e7a1f6d Update README.md
* b1c3e44 Add feature/update-title branch
| * f3d2a8b Initial commit
|/
* 8c4d7e1 Merge pull request #1 from origin/feature/update-title
This version includes a graphical representation of branch history. Notice the origin/feature/update-title branch next to one of the commits.
You can see that the commit the branch points to splits from the main branch (the master branch). This shows where changes on the origin/feature/update-title branch began, and any changes made there do not affect the master branch.
Later, the origin/feature/update-title branch rejoins the master branch in the next commit, which is noted as a merge:
Sample output:
* 8c4d7e1 Merge pull request #1 from origin/feature/update-title
|\
| * f3d2a8b Add feature/update-title branch
|/
* e7a1f6d Update README.md
This indicates that the changes from the origin/feature/update-title branch were successfully merged back into the master branch.
Some common commands:
-
View changes
git log
git log --summary
git log --stat
git log --graph
git log --oneline
git log --oneline --decorate=no
git log --walk-reflogs -
Preview changes before merging
git diff [source branch] [target branch] -
Recover lost commits or branches by showing all actions performed in the repository.
git reflog -
Show details about a specific state of the repository as recorded in the reflog.
git show HEAD@{index}
git show
The git show command displays detailed information about various Git objects, with the default action being to show details of the last commit. It combines commit details, similar to the git log command, with content changes like the git diff command, making it a great option for quickly gathering information about a commit.
To view the latest commit details, you can run:
git show
Sample output:
commit 2dca4178sdsdd86789as7ea157dsdsd67sdff3d6 (HEAD -> new_branch, origin/master, origin/HEAD, master)
Merge: ae05432 f2d9c95
Author: Matt Martinez <matthewmartinez1003@gmail.com>
Date: Wed Nov 20 16:50:24 2019 -0600
Merge pull request #1 from cloudacademy/feature/update-title
update title
By default, the output resembles that of git log, showing the most recent commit. It also includes any content changes made in that commit, similar to the diff command.
You can also specify a commit ID to see details for a specific commit. For example:
git show 2dca417
Sample Output for Specific Commit:
commit 2dca4178sdsdd86789as7ea157dsdsd67sdff3d6
Author: Matt Martinez <matthewmartinez1003@gmail.com>
Date: Wed Nov 20 16:50:24 2019 -0600
Merge pull request #1 from cloudacademy/feature/update-title
diff --git a/README.md b/README.md
index ae05432..f2d9c95 100644
--- a/README.md
+++ b/README.md
@@ -1,2 +1,2 @@
Static Website Example
-Update this title
+Updated this title
This command provides both the commit details and the changes made in that specific commit.
git blame
The git blame command helps you identify who made changes to specific lines in a file. It displays each line of a file alongside the commit information, making it easy to track changes over time.
You can use the command like this:
git blame README.MD
Sample output:
homelabs:~/example-git-repo$ git blame README.MD
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 1) Static Website Example
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 2) ----------------------
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 3)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 4) To be used with Cloud Academy labs.
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 5)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 6)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 7) License
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 8) ----------------------
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 9)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 10) This static website is based on the Dimension template by [HTML5 UP](https://html5up.net/)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 11)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 12) Creative Commons License
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 13) All of the site templates I create for [HTML5 UP](https://html5up.net/) are licensed under the Creative Commons Attribution 3.0 License, which means you can:
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 14) - Use them for personal stuff
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 15) - Use them for commercial stuff
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 16) - Change them however you like
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 17)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 18)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 19) ... all for free, yo. In exchange, just give HTML5 UP credit for the design and tell your friends about it :)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 20)
^ae05432 (Ted Mosby 2019-11-19 15:31:36 -0700 21) More info [here](https://html5up.net/license).
The output from the git blame command shows each line of a file as a row. From left to right, each row includes:
- A commit ID
- The name of the committer
- The timestamp of when the change was made
- The content of the line
Developers use this command to find out who made specific changes and when those changes were made.
git tag
The git tag command lets you create tags, which are Git objects that point to specific commits. Tags are useful for tracking versions of your codebase and are often used to mark release versions (like v1.0.0).
To create a tag, run:
git tag 0.1.0
Sample Command and Output:
$ git tag
0.1.0
After creating the tag, you can view it with the git tag command, which lists all tags in the repository.
When you look at the commit history with:
git log --oneline
Sample Output:
2dca417 (HEAD -> new_branch, tag: 0.1.0, origin/master, origin/HEAD, master) Merge pull request #1 from cloudacademy/feature/update-title
f2d9c95 (origin/feature/update-title) update title
ae05432 Initial commit
In this output, the tag 0.1.0 is associated with the commit 2dca417. This demonstrates how tags point to specific commits, providing an easy way to reference important points in your project's history.
Tags are static and will not change, unlike branches, which move as new commits are added. This makes tags ideal for marking stable releases or versions of your codebase.
You can also use tags in various commands, like checking out, pushing, and pulling, ensuring you manage a specific version of the codebase.