git manual

Last update: Thu Jun 5 22:25:41 2025

More than a manual, a small list of reminders for me. If you find it useful, good for you.

One liners & frequent commands

Cancel your git add

Don't delete anything, just "un-add" everything.

git reset

Rollback all your local changes and go back to latest commit

You messed up, nothing works... happens. My reason #1 to use a VCS, so you can mess up thing and always go back to latest known status in one command. This WILL delete files created afterward also.

git reset --hard
git clean -f -d

Have git remember your credentials

Ok there are better and safer ways, just let me be.

#store my credentials in a clear text file (hum hum) in my home folder/.git-credentials
git config --global credential.helper store

HOWTOs

Migrate a folder with its history to another repository

I had to do that because I put everything (C#, python, microcontroller, eagle,...) files in one repository which obviously became too big and kind a messy. So I decided to move out some chuncks of it outside to a dedicated smaller repo (ie: eagle files in May2020). This is how I did it.

Foreword: I based this on that tutorial that I followed but it wasn't clear enough to me so let me re-explain it my way, but credits go to the author of the original one.

Theory

Basically you add to the target-repo a reference to the source-repo, merge the histories, remove the reference to the source-repo and done. But there's a few steps to that.
You need to remove everything you don't want from source-repo before copying to target-repo. Obvious, because otherwise the whole hisotry of everything would be duplicated, a waste of space and not your goal (you want 1 folder to move).

#Say you want to move folder source-repo/FOLDER_TO_KEEP to target-repo/NEW_FOLDER with its whole history and content.

#create a dummy work folder
mkdir temp-repo
cd temp-repo

#checkout source-repo there
git clone [source-repo-url]

#remove immediately the link to the origin to avoid messing up the original one
cd source-repo
git remote rm origin

#there, now even if you mess-up your changes won't be pushed to github

#now a command you don't often type: it will delete everything in your repo EXCEPT the FOLDER_TO_KEEP
# and !!surprise!!, it will move the content of FOLDER_TO_KEEP to the root of the repo
git filter-branch --subdirectory-filter [FOLDER_TO_KEEP] -- --all

#pruning & cleaning violently
git reset --hard
git gc --aggressive 
git prune
git clean -fd

#now your repo is clean as a whistle of any record of information except the FOLDER_TO_KEEP part BUT now the files are at the root of the repo

[OPTIONAL]

#maybe you want the files in a subfolder of your repo, not at the root? so let's do it
mkdir NEW_FOLDER
mv -R * NEW_FOLDER/

#make sure everything is committed
git add -A .
git commit

[/OPTIONAL]

#now go to your target-repo
cd ../target-repo

#plug a reference to your modified copy of the source-repo. Not the real source-repo, the one you just cleaned up in temp-repo/ folder
#"dummy-name" is just to give a label to the reference. anything is fine, you'll delete it in 2 minutes. I will go with "dummy-name"
git remote add dummy-name [path-to-temp-repo-folder]

#now the magical mariage of the 2 repos history
git pull dummy-name master --allow-unrelated-histories

#remove that dummy reference
git remote rm dummy-name

#and now the local target-repo has gained all the files and history of source-repo concerning FOLDER_TO_KEEP, time to push to github
git push 

#go grab your preferred drink, you earned it

All content on this site is shared under the MIT licence (do what u want, don't sue me, hat tip appreciated)
electrogeek.tokyo ~ Formerly known as Kalshagar.wikispaces.com and electrogeek.cc (AlanFromJapan [2009 - 2025])