As I was looking for easy assignments for the Open Source Development Course I found something very troubling which is also an opportunity for a lot of teaching and a lot of practice.
Some files don't need to be in git
The common sense dictates that we rarely need to include generated files in our git repository. There is no point in keeping them in our version control as they can be generated again. (The exception might be if the generation takes a lot of time or can be done only during certain phases of the moon.)
Neither is there a need to store 3rd party libraries in our git repository. Instead of that we store a list of our dependencies with the required version and then we download and install them. (Well, the rightfully paranoid might download and save a copy of every 3rd party library they use to ensure it can never disappear, but you'll see we are not talking about that).
.gitignore
The way to make sure that neither we nor anyone else adds these files to the git repository by mistake is to create a file called .gitignore, include patterns that match the files we would like to exclude from git and add the .gitignore file to our repository. git will ignore those file. They won't even show up when you run git status.
The format of the .gitignore file is described in the documentation of .gitignore.
In a nutshell:
/output.txt
Ignore the output.txt file in the root of the project.
output.txt
Ignore output.txt anywhere in the project. (in the root or any subdirectory)
*.txt
Ignore all the files with .txt extension
venv
Ignore the venv folder anywhere in the project.
There are more. Check the documentation of .gitignore!
Not knowing about .gitignore
Apparently a lot of people using git and GitHub don't know about .gitignore
The evidence:
Python developers use something called virtualenv to make it easy to use different dependencies in different projects. When they create a virtualenv they usually configure it to install all the 3rd party libraries in a folder called venv. This folder we should not include in git. And yet:
There are 452M hits for this search venv
In a similar way NodeJS developers install their dependencies in a folder called node_modules. There are 2B responses for this search: node_modules
Finally, if you use the Finder applications on macOS and open a folder, it will create an empty(!) file called .DS_Store. This file is really not needed anywhere. And yet I saw many copies of it on GitHub. Unfortunately so far I could not figure out how to search for them. The closest I found is this search.
Misunderstanding .gitignore
There are also many people who misunderstand the way .gitignore works. I can understand it as the wording of the explanation is a bit ambiguous. What we usually say is that
If you'd like to make sure that git will ignore the
__pycache__folder then you need to put it in.gitignore.
A better way would be to say this:
If you'd like to make sure that git will ignore the
__pycache__folder then you need to put its name in the.gitignorefile.
Without that people might end up creating a folder called .gitignore and moving all the __pycache__ folder to this .gitignore folder. You can see it in this search
Help
Can you suggest other common cases of unnecessary files in git that should be ignored?
Can you help me creating the search for .DS_store in GitHub?
Updates
More based on the comments:
-
.ofiles the result of compilation of C and C++ code: .o -
.classfiles the result of compilation of Java code: .class -
.pycfiles are compiled Python code. Usually stored in the__pycache__folder mentioned earlier: .pyc
How to create a .gitignore file?
A follow-up post:
Top comments (49)
Did you know the command
git clean -Xfdwill remove all files from your project that match the current contents of your .gitignore file? I love this trick.Be careful with this one. Some of my repos have bits and pieces I expressly never commit and are in .gitignore but also don't want to branch/stash those things either. Things like files with sensitive configuration information or credentials in them that exist for development/testing purposes but should never reach GitHub.
Maybe use environment variables in your IDE? Or if you're on Linux, you can set those values automatically when you enter the folder with
cd. This is much safer in both situations, you will never commit this data and will never delete it.For e.g. syncing it between devices, use password manager (like BitWarden).
The thing with repos is that git clean -Xfd should not be dangerous, if it is then you have important information that should be stored elsewhere, NOT on the filesystem.
Please learn to use a proper pgpagent or something.
The filesystem should really be ephemeral.
Information has to be stored somewhere. And that means everything winds up stored in a file system somewhere.
I was just looking for this comman I wanted to remove some of the sqlite files from GitHub
This won't remove the already committed files from github. It removes the files from your local disk that should not be committed to git.
Lifesaver!
Game engine projects often have very large cache folders that contain auto generated files which should not be checked into repositories. There are well established .gitignore files to help keep these out of GitHub, but people all to often don't use them.
For Unity projects, "Library" off the root is a cache (hard to search for that one, it's too generic).
For Unreal, "DerivedDataCache" is another (search link)
There's also visual studio's debug symbol files with extension .pdb. these can get pretty damn big and often show up in repos when they shouldn't: search link
Thanks! That actually gave me the idea to open the recommended gitignore files and use those as the criteria for searches.
See also gitignore generators like gitignore.io. For example, this generated .gitignore has some interesting ones like
*.logand*.tmp.Does GitHub really store duplicate files?
I don't know how github stores the files, but I am primarily interested in the health of each individual project. Having these files stored and then probably updated later will cause misunderstandings and it will make harder to track changes.
Duplicate or not, git clone is create them. 😞
I am not sure I understand what you meant by this comment.
It doesn't matter if github stores it in duplicate or not, because git clone will create it unnecessarily on the client side.
Right
He wanna make force ppl do what he wants, assuming they dumb.
UPD sorry, wrong pic
I am sorry, but it is unclear what you mean by that comment and what does that image refer to? Could you elaborate, please?
He demonstrates how to lighten your open source projects with the use of
.gitignore. 👍🏼At no time does he point at people and tell them that. Why do you think like that? 🤔
I manage a GitHub Enterprise instance for work and this is soooo incredibly important actually. The files you commit to git really build up overtime. Even if you "remove" a file in a subsequent commit, it is still in git history, which means you're still cloning down giant repo history whenever you clone. You might think: "oh well so what? What's the big deal? This is a normal part of the development cycle"
Let's couple these large repo clones with automation that triggers multiple times a day. Now let's say that a bunch of other people are also doing automated clones of repos with large git histories. The amount of network traffic that this generates is actually significant and starts to impact performance for everyone. Not to mention that the code has to live on a server somewhere, so its likely costing your company a lot of money just o be able to host it.
*General advice whether you're using GitHub Enterprise or not:
*
Utilize a .gitignore from the start! Be overzealous in adding things to your .gitignore file because its likely safer for you. I use Toptal to generate my gitignores personally
If you're committing files or scripts that are larger than 100mb, just go ahead and use git-lfs to commit them. You're minimizing your repo history that way
Try to only retain source code in git. Of course there will be times where you need to store images and maybe some documents, but really try to limit the amount of non source-code files that you store in git. Images and other non text-based files can't be diffed with git so they're essentially just reuploaded to git. This builds up very quickly
Weirdly enough, making changes to a bunch of minified files can actually be more harmful to git due to the way it diffs. If git has to search for a change in a single line of text, it still has to change that entire (single) line. Having spacing in your code makes it easier to diff things with git since only a small part of the file has to change instead of the entire file.
If you pushed a large file to git and realized that you truly do not need it in git, use BFG repo cleaner to remove it from your git history. This WILL mess with your git history, so I wouldn't use it lighty, but its an incredibly powerful and useful tool for completely removing large files from git history.
Utilize git-sizer to see how large your repo truly is. Cloning your repo and then looking at the size on disk is probably misleading because its likely not factoring in git history.
Review your automation that interacts with your version control platform. Do you really need to clone this repo 10 times an hour? Does it really make a difference to the outcome if you limited it to half that amount? A lot of times you can reduce the number of git operations you're making which just helps the server overall
I was really shocked, i read your article 3 times and opened the node modules search to believe this.
Wow GitHub should start to alert this people!
github.com/community/community#mak...
Ignored files are usually build artifacts and machine generated files that can be derived from your repository source or should otherwise not be committed. Some common examples are: dependency caches, such as the contents of /node_modules or /packages. compiled code, such as .o , .pyc , and .class files.
I've updated the article based on your suggestions. Thanks.
Good explanation of .gitgnore
Don’t forget those .env files as well!
GitHub’s extension search parameter doesn’t require the dot, so your .DS_Store search should work if you make that small change
extension:DS_Storehttps://github.com/search?q=extension%3ADS_Store&type=Code
I was quite used to configuring everything by text file when I first encountered Git in 2005, but I still needed a little help and a little practice to get used to .gitignore. :) I think the most help was seeing examples in other peoples' projects; that's what usually works for me.
The
.gitignorefolder search link is wrong. It should have the query.gitignore/not.gitignorehttps://github.com/search?q=path%3A.gitignore%2F&type=code
Yours looks more correct, but I get the same results for both searches. Currently I get for both searches:
1,386,986 code resultsWeird, I get two different results. 🤣
.gitignore/.gitignoreYou use night-mode and I use day-mode. That must be the explanation. 🤔
Also I have a menu at the top, next to the search box with items such as "Pull requests", "Issues", ... and you don't. Either some configuration or we are on different branches of their AB testing.
There is gitignore.io service that can be used to generate good
.gitignorefile for the programming language and/or framework that you use, and per-user or per-repository ignore file for the IDE you use.Some comments may only be visible to logged-in visitors. Sign in to view all comments. Some comments have been hidden by the post's author - find out more