$ git log
commit ab910bf6af5ef079ec094c5cbe8e989d8cab20ac
Author: jeremy.bardon <jeremy.bardon@>
Date: Fri Nov 23 17:50:06 2018 +0100
Write React introduction
Explore your project versions
Fine, you created multiple version of your codebase with commits. It’s time to list all versions, visualize their content and also compare them.
In my opinion, graphic interfaces are more efficient than git commands for this purpose.
I’ld recommend gitk which comes with git out of the box.
It comes along with git gui which helps to commit and manage your staging area.
Besides, many open source Git GUI allow using git without the CLI, look at the official list.
The most famous includes SourceTree from Atlassian, GitKraken and GitHub Desktop.
Yet, I’m going to introduce the basic commands. It can be handy when you don’t have a screen (ssh on a server) and even to write scripts.
The command which lists commits is git log.
This will output the list of all commits.
You can see many details: who did the commit, when and the message.
Did you notice this long weird thing beside commit? It’s a SHA1, the unique identifier for this commit. If you specify a file, you’ll get all the commits affects this very file (this one is really useful).
Log output contains a bunch of data and is also highly customisable. That’s why it exists a famous lol alias. This one set some parameters to the log command to make it give a short and effective history.
alias.lol=log --graph --decorate --pretty=oneline --abbrev-commit alias.st=status alias.cp=cherry-pick alias.br=branch alias.co=checkout alias.ci=commit
There are many aliases for everyday commands.
You can add them in your global git configuration with git config --global --add alias.ci="commit".
Now, you can type git ci, the alias is replaced with the content from the configuration.
If you want to see the changes for one commit, use git show.
By default, you’ll see all the modifications in your console.
Add --name-only to have changed files list without the details.
$ git show 7bdbb4d --name-only $ git show 7bdbb4d react.txt
It’s time to compare files between different commits. Git is powerful in this area, you can see the differences for a file or a directory among multiple commits. For instance, you can see all the differences in your codebase between commit A and D (it’ll also include commit B and C changes).
$ git diff A..C $ git diff A..C react.txt
When you don’t give commits to diff, you’ll get the difference in your working directory but not staged for commit.
The --staged option only shows differences for files in the staging area.
A quick trick, set not parameters but make the comparision with HEAD to see not staged and staged files.
$ git diff > react.txt $ git diff --cached > vue.txt $ git diff HEAD > react.txt > vue.txt
Great, you can see differences among multiple commits.
What about being able to reset your project to a specific version for testing?
You can do it with git checkout.
$ git checkout 7bdbb4d $ git checkout HEAD
Actually, when you checkout on a commit you’ll be in a detached HEAD state. It means you can’t commit in this state. To go back to your original state, you can use the HEAD value.
If you’re looking for when a bug appeared, git has something for you.
First, find any version where the bug wasn’t present.
Then launch git bisect, it’ll use a dichotomous algorithm to find the commit efficiently.
Git will perform a binary search from the commit you identified to the most recent commit. After an automatic checkout, it’ll ask if the current commit contains the bug or not. With your answer, git will deduce what’s the next commit to check until it found the one which introduced the bug.