Git

CREATED

2017 May 19th

UPDATED

2020 Aug 18th

Use a git patch file

How to apply a git patch file.

Good resource here: https://www.devroom.io/2009/10/26/how-to-create-and-apply-a-patch-with-git/

# see the changes in the patch file
git apply --stat the-patch-file.patch
# test if ther's going to be issues
git apply --check the-patch-file.patch
# no issues, cool
git apply the-patch-file.patch

Change the git init default branch name

Don’t want to have the default branch called master?

mkdir -p ~/.config/git/template
echo 'ref: refs/heads/main' > ~/.config/git/template/HEAD
git config --global init.templateDir ~/.config/git/template/

Since version 2.28 of Git this can be done using this command:

git config --global init.defaultBranch main

For more info: Highlights from Git 2.28

Add a repo from your machine to GitHub

Create a new repo and push it to GitHub.

echo "# name-of-your-awesome-repo" >> README.md # add repo name to README.md
git init # init the repository
git add README.md
git commit -m "first commit"
git remote add origin https://github.com/your-username/name-of-your-awesome-repo.git
git push -u origin master

The first four commands can be ignored if you have a repo you’re already working on (git)committing to.

Latest changes from repo to your machine

git pull

Add tracking information to your work

Assuming that you are working on the master branch then

git branch --set-upstream-to=origin/master

You can set it to whatever branch you want to track changes for

git branch --set-upstream-to=origin/<branch>

This will mean you can just do git pull and the latest changes will be pulled to your origin

What branch

git branch # shows what branch you're on
git branch -r # shows remote branches
git branch -a # shows all branches

Create a local branch and push it to GitHub

Want to make your feature branch and get it on GitHub?

Make your branch first then:

git push --set-upstream origin <branch-you-just-created>

Check remotes

git remote -v

Sync a remote fork on your machine

First configure the local to point to the remote upstream

git remote -v
git remote add upstream https://github.com/ORIGINAL_OWNER/ORIGINAL_REPOSITORY.git
git remote -v
git fetch upstream
git checkout master
git merge upstream/master

You then use git merge to update any branch on the upstream repository:

git merge upstream/dev

Take a look at syncing a fork for more details.

Sync a remote fork on Github

Open your fork on GitHub.
Click on Pull Requests.
Click on New Pull Request. By default, GitHub will compare the original with your fork, and there shouldn’t be anything to compare if you didn’t make any changes.
Click on Try switching the base. Now GitHub will compare your fork with the original, and you should see all the latest changes.
Click on Click to create a pull request for this comparison and assign a predictable name to your pull request (e.g., Update from original).
Click on Send pull request.
Scroll down and click Merge pull request and finally Confirm merge. If your fork didn’t have any changes, you will be able to merge it automatically.

2fa

Using two factor authentication? Then use the following so you’re not adding in your auth token each time you want to push your code.

git remote set-url origin https://your-username:[email protected]/your-username/your-repo.git

Change `origin` url

If you want to change the origin url you can use the set-url command

git remote set-url origin https://github.com/username/new-repo-name

Add code on your machine to new repo

Via terminal navigate to your code folder.

git init

Add your files.

git add .

Adding a folder use the following syntax or it’ll get added as a BLOB.

git add nameOfFolder/*

Commit to local repo.

git commit -m 'some detailed message'

To add your files to the remote repo, first add your remote repo

git remote add origin [remote repository URL] # Sets the new remote
git remote -v # Verifies the new remote URL
git push origin master

For more info check out: adding an existing project to github using the command line

Delete branches

Delete local branch.

git branch -D branch-name

Remove local branches that are not on the remote.

git remote prune origin --dry-run
# remove --dry-run if you're happy to delete

Remove local branches that were created from remote branches.

git branch --merged master | grep -v '^[ *]*master$' | xargs git branch -d

Merge master branch into feature branch

How to merge the master branch into the feature branch? This will come up often if you are working on a team with other devs and you want to update your feature branch to include the latest changes.

# checkout your feature branch
git checkout feature1
# merge master into it
git merge master

Merge two repos

If you want to merge project-a into project-b:

cd path/to/project-b
git remote add project-a path/to/project-a
git fetch project-a
git merge --allow-unrelated-histories project-a/master # or whichever branch you want to merge
git remote remove project-a

Stop tracking a file

If you have .env files that are tracked by Git and want to ignore them so your API keys don’t get added to GitHub use:

git update-index --assume-unchanged <file>

Stop tracking a previously tracked folder

First add the folder to your .gitignore then remove the folder from your local git tracking with:

git rm -r --cached <folder>

Start tracking a previously un-tracked file

git update-index --no-assume-unchanged <file>

Cloning a repo from someone else’s GitHub and pushing it to a repo on my GitHub

So you make a clone of a repo that sin’t yours, make some changes then realise that you need to add it to your GitHub account to make a PR.

git remote -v
origin  https://github.com/other-user/other-username/other-repo (fetch)
origin  https://github.com/other-user/other-username/other-repo (push)

You just need to set the clone your working on as the downstream repo.

# add as downstream
git remote add downstream https://github.com/your-username/your-repo
# or as your username
git remote add your-username https://github.com/your-username/your-repo

Now it should look something like this:

git remote -v
origin  https://github.com/other-username/other-repo (fetch)
origin  https://github.com/other-username/other-repo (push)
downstream  http://github.com/your-username/your-repo (fetch)
downstream  http://github.com/your-username/your-repo (push)

You can then push your changes to the downstream repo and make a PR via GitHub.

Remove an `upstream` repository

If you no longer need a reference to a forked repository then remove it with the following:

git remote rm upstream

Clone a repo and give it a different name

git clone https://github.com/your-username/repo-name new-repo-name

Using Husky?

If you are pushing right after a commit, you can use git push --no-verify to avoid running all the tests again.

If you make a trivial change and want to commit git commit -m 'some detailed message' --no-verify will skip your precommit and prepush scripts.

How to read last commit comment?

git show # is the fastest to type, but shows you the diff as well.
git log -1 # is fast and simple.
git log -1 --pretty=%B # if you need just the commit message and nothing else.

Remove commit from pull request

Read this for more detail on how to revert.

This was the simplest approach I found:

# Checkout the desired branch
git checkout <branch>
# Undo the desired commit
git revert <commit>
# Update the remote with the undo of the code
git push origin <branch>

Rather than use the last part I unstaged the changes in VSCode which I think did the same thing.

Conflicts between Windows Git and WSL Git?

If you are having issues with changes showing in Windows Git and not Windows Subsystem Linux Git (For a Windows WSL Dev set-up) then check the settings of each environment by using:

git config --list --show-origin

Remove any conflicting settings then try again.

If you want to rename a branch while pointed to any branch, do:

git branch -m <oldname> <newname>

If you want to rename the current branch, you can do:

git branch -m <newname>

A way to remember this, is -m is for “move” (or mv), which is how you rename files.

Git ref log

Want to know what work you have done on a repo? Use git reflog to displpay all the commits.

# show all changes for the last 90 days
git reflog show -a
# show changes with a date
git reflog --date=iso

https://stackoverflow.com/questions/17369254/is-there-a-way-to-cause-git-reflog-to-show-a-date-alongside-each-entry

Use SSH in place of HTTPS

Get your SSH set up on your machine and add a key to GitHub, more on that here: https://egghead.io/lessons/javascript-how-to-authenticate-with-github-using-ssh

You will then need to pick your Clone with SSH option from the Clone or download section on your repo page.

Once you have taken the link from there you will need to set the repo remote to the SSH URL

git remote set-url origin [email protected]:username/repo-name-here.git

Where username is the username of the repo owner and repo-name-here is the name of that user’s repository.

How to authenticate with GitHub using SSH

Check that there are no rsa files here before continuing, use (bash or Git bash if you’re on Windows):

ls -al ~/.ssh

If there’s nothing there then generate a new keygen with:

ssh-keygen -t rsa -b 4096 -C [email protected] # add your email address 👍

If you decide to use a password for your SSH key see SSH Keys With Passwords

Now using ls -al ~/.ssh will show our id_rsa.pub file.

Add the SSH key to the SSH agent:

# for mac and Linux from bash, also from Windows Git Bash
eval "$(ssh-agent -s)"
# for Git Bash on Windows
eval `ssh-agent -s`
# fir Fish shell
eval (ssh-agent -c)

Add RSA key to SSH with:

ssh-add ~/.ssh/id_rsa

Copy your key to clipboard with one of the following:

clip < ~/.ssh/id_rsa.pub # Windows
cat ~/.ssh/id_rsa.pub # Linux
pbcopy < ~/.ssh/id_github.pub # Mac

Add a new SSH Key to your GitHub profile from the settings page by clicking the New SSH key button and paste in your key. Save it…

Then authenticate with:

ssh -T [email protected]

If you go back to the GitHub setting page and refresh the key icon should go from black to green. 🎉

If you add a password to your SSH key you will find yourself entering the password to authenticate on each [pull, push] operation. This can get tedious, especially if you have a long password in your keys.

Add the following line to your ~/.ssh/config/ file:

AddKeysToAgent yes

Open or create the ~/.ssh/config file with:

nano ~/.ssh/config

The SSH agent will also need to be started on each terminal session now to store the keys in, add the following to your ~/.bashrc file:

[ -z "$SSH_AUTH_SOCK" ] && eval "$(ssh-agent -s)"

Open the ~/.bashrc file with:

nano ~/.bashrc

Now the SSH agent will start on each terminal session and you will only be prompted for the password on the first pull, push operation.

Use multiple SSH keys

If you have more than one GitHub account or if you have AWS code commit account then you will need to set up a config file, add your SSH key the same as detailed in How to authenticate with GitHub using SSH and give the key a different name:

# ls ~/.ssh
~/.ssh/id_rsa_github_1
~/.ssh/id_rsa_github_2
~/.ssh/id_rsa_git_aws

You can delete all cached keys before, with:

ssh-add -D

You can check your saved keys, with:

ssh-add -l

Set up the SSH config file, check to see if you haven’t got a config file already set up with:

ls -al ~/.ssh/

If you haven’t got a config file there then:

cd ~/.ssh/
touch config

Use your text editor of choice, in this example we’ll use nano:

nano config

Add your configuration:

AddKeysToAgent yes

# github_1 account
Host github.com-github_1
	HostName github.com
	User git
	IdentityFile ~/.ssh/id_rsa_github_1

# github_2 account
Host github.com-github_2
	HostName github.com
	User git
	IdentityFile ~/.ssh/id_rsa_github_2

# AWS code commit account
Host git-codecommit.*.amazonaws.com
	User AWSUSERNAME
	IdentityFile ~/.ssh/id_rsa_git_aws

Clone your repo and modify the config file of the repo as detailed here: Specify multiple users for myself in .gitconfig?

There’s a great Gist detailing this here for more detail if needed.

Re-use SSH keys, from one machine to another

If you want to avoid creating multiple SSH keys for different environments and move your .ssh folder from one machine to another then you can do the following:

Copy your .ssh and .gitconfig files:

Copy from Linux to Windows

cp ~/.ssh/* /c/Users/Scott.Spence/.linuxFiles/.ssh/
cp ~/.gitconfig /c/Users/Scott.Spence/.linuxFiles/

Copy from Windows to Linux

cp /mnt/c/Users/Scott.Spence/.linuxFiles/.ssh/* ~/.ssh/
# Reset the permissions back to default:
sudo chmod 600 ~/.ssh/id_rsa
sudo chmod 600 ~/.ssh/id_rsa.pub
cp /mnt/c/Users/Scott.Spence/.linuxFiles/.* ~/
chmod 644 ~/.gitconfig

Start the SSH agent with:

eval "$(ssh-agent -s)" # for mac and Linux from bash, also from Windows Git Bash

Add your SSH key to the ssh-agent with:

ssh-add ~/.ssh/id_rsa

Then authenticate with:

# GitHub
ssh -T [email protected]
# Bitbucket
ssh -T [email protected]

Using SSH over the HTTPS port

SSH can be tunnelled over HTTPS if the network you are on blocks the SSH port.

Test if SSH over HTTPS is possible with:

ssh -T -p 443 [email protected]

If you get a response then, edit your ~/.ssh/config file and add this section:

Host github.com
  Hostname ssh.github.com
  Port 443

Check that you have a key already added with:

ssh-add -l

If nothing is listed then add in your key with:

ssh-add ~/.ssh/id_rsa

Test that is has worked with:

ssh -T [email protected]

Change SSH key password

Tired of typing your SSH key password because you made it a 32 characters and can’t stand the monotony anymore?

Still want to have a SSH key password on your existing SSH key?

Use:

ssh-keygen -p -f ~/.ssh/id_rsa

Specify multiple users for myself in .gitconfig?

Want to have different git credentials for one specific repository?

You can configure an individual git repo to use a specific user/email address which overrides the global configuration.

To list out the config for the repo:

git config --list --local

From the root of the repo, run:

git config user.name 'Your Name'
git config user.email '[email protected]'

Whereas the default user / email is configured in your ~/.gitconfig

git config --global user.name 'Your Name'
git config --global user.email '[email protected]'

Cant remember what your last git commit said?

git show

Rebase changes

If you’re working on a team and there have been changes to the main branch you want to push your changes to, you can rebase before submitting a PR.

In this scenario we’re going to rebase our feature branch off of the develop branch

# switch from your feature to get latest develop changes
git checkout develop
git pull
# checkout the feature branch and rebase
git checkout feature
git rebase develop

Then use the prompts from there in conjunction with your text editor to add in the changes.

# add a change
git add
# continue the rebase
git rebase --continue
# have an unrelated change, nothing to correct
git rebase --skip
# oh DERP! Want to start over?
git rebase --abort

Rebase accept incoming in bulk

If you have a large file (like a package-lock.json) that you want to accept all the incoming changes from then.

Whilst you’re in rebase you’ll need to check out the file from your incoming branch then add it as the new file.

# checkout the file
git checkout temp-branch -- package-lock.json
# add the file whilst in rebase
git add package-lock.json
# continue with the things
git rebase --continue

See differences between two branches

If you want to see the difference between two branches then use the git built in diff tool.

git diff branch1..branch2

See differences between two files

If you want to see the difference between two file across different branches then use.

git diff branch1..branch2 package.json

Revert to a previous commit

Find the commit you want to revert to, then:

git reset hashOfCommit

Then reset to the branch on the origin:

# if I wanted to push back to the develop branch on GitHub say
git reset --soft origin/develop

Reference: https://stackoverflow.com/questions/11829911/push-changes-without-pull

Gitignore

You can automate the creation of your projects gitignore file using the gitignore API.

Setup the API:

git config --global alias.ignore '!gi() { curl -sL https://www.gitignore.io/api/$@ ;}; gi'

Add to your shell configuration:

Bash

echo "function gi() { curl -sL https://www.gitignore.io/api/$@ ;}" >> ~/.bashrc && source ~/.bashrc

checkout gi list for the languages and editors supported. You can issue the following command inside your project

gi linux,visualstudiocode,node >> ./.gitignore

If you find yourself using the same .gitignore on your projects you can create a global file (i.e. .gitignore_global), and copy to your new project.

Reference: https://docs.gitignore.io/install/command-line

>>> END OF CHEAT SHEET <<<