You’ve been developing your projects for weeks, and everything’s going swimmingly. Except, one fine day, your project manager asks you to go back to a previous version of the project. He also needs to know who made which commit! 
Luckily, Git has history tools specifically designed for this type of situation.
Forgotten Something? Git Reflog!
The purpose of a version control system is to save the changes made to your code. It allows you to consult your project history to:
Find who has contributed to what.
Pinpoint where bugs were introduced.
Undo changes that have caused problems.
Sounds great, but the history is totally useless if you don’t know how to use it! This is where the command git log comes into play.
git log
By default, git log lists commits in reverse chronological order. This means that the most recent commits appear first. This command shows every commit made, along with its SHA ID, the commit author, the date, and the commit message.
Git has an even more powerful tool, which takes logs to the extreme!
git reflog
git reflog logs commits as well as all other local actions—your changes to messages, merges, resets… everything! 
Like git log , git reflog shows a SHA-1 ID for every action. Thanks to the SHA, this makes it very easy to go back to a specific action. This command is a lifeline if you make a mistake. To get back to any specific action, take the first eight characters of its SHA and enter the following:
git checkout e789e7c
Whoosh! You’ve gone back in time! 
Who’s Been Messing Around in Your Repository? Git Blame
If you discover a bug in your project, you’ll need to find out where it came from and who changed each line of code. This is where git blame comes in useful.
The command git blame allows you to examine the content of a file, line by line, and find out the date when each line was changed and the name of the person who did it.
git blame myFile.php
git blame shows the following for each line changed:
Its ID.
The author.
The timestamp.
The line number.
The line content.
Withgit blame, you can use your detective skills to solve crimes against your project!
You Want to Cherry-Pick Specific Commits
When you’re working with a team of developers on a medium to large project, managing changes between several Git branches can get complicated. Sometimes, you don’t want to merge a whole branch with another, you just want to choose one or two specific commits. This process is called cherry-picking!
Let’s imagine you’re working on the branch “My changes,” and you’ve already made several commits. Your colleague needs one of these changes to deliver it to the client, but not the others. In this very specific case, you can use git cherry-pick ! Using this command, you can select one or several commits via their SHA (these things are everywhere!) and migrate them to the main branch without merging the whole “My changes” branch.
git cherry-pick d356940 de966d4
Here, we’re taking the two commits with SHA ID d356940 and de966d4, and adding them to the main branch, without removing them from the current branch. We’re duplicating them!
Let’s Recap!
Using git log, you can view the commit history on the current branch.
git reflogis identical to git log. This command also shows all local actions carried out.You can use
git checkoutwith a SHA-1 ID to go back to a specific action.git blameshows you who made which changes to a file on what date, line by line.Using
git cherry-pickwith the SHA-1 ID of the commit concerned, you can select a commit and apply it to the current branch.
You’re now equipped with all the knowledge you need to correct your mistakes in Git! Move to the last chapter of the course to recap what you’ve learned and access extra resources!
