git-training

Two factor Authentication

We should safeguard our git account by using two factor authentication.
Check out this link for more details

Using Git via SSH and HTTPS

When 2FA is enabled, git will ask for password for each operation. We can avoid entering password by two ways

API Token
SSH Key

Create an API Token

Create a new classic token by visiting this link
Enter a note and select all the scopes
Click on generate token and ensure you copy the token and save it somewhere

Setup an ssh key

Run the below commands (passphrase is optional, but it's strongly recommended)

ssh-keygen -t ed25519 -C "your_email@example.com"
cat ~/.ssh/id_ed25519.pub

Add the public key to your profile by visiting this link

`gh` command line

Install the gh command line by visiting this link

Git commands

Help section

git help

Configuring git with your data

git config --global user.name "Your Name"
git config --global user.email your_email@example.com
git config --global init.defaultBranch main
git config --global core.editor vim
cat ~/.gitconfig

Initializing a git repo (replace the value YOUR_USER_NAME with your actual user name)

mkdir random-git-repo
git init
touch README.md
git add README.md
git commit -m "initializing repo"
gh repo create --source=. --public
git push origin main

# Enter email and api token and then check the repo for your commit on Github

Fork the repo https://github.com/keshavprasadms/git-training and clone the forked repo (replace the value YOUR_USER_NAME with your actual user name)

git clone https://github.com/YOUR_USER_NAME/git-training

# See clone to a directory
# See clone and checkout a branch

Add a new file, commit and push

echo 'print("Hello there!")' > hello.py
python hello.py
git add hello.py
git commit -m "feat: adding hello.py"
git push origin main

Every push is asking for a password? If yes, export an environment variable (replace the value YOUR_API_TOKEN with your actual api token)

export GITHUB_TOKEN=YOUR_API_TOKEN

View current branch and checkout a new branch, check staged area using status command, check diff, commit and push

git branch
git checkout -b feature-1
echo 'print("This is feature-1!")' >> hello.py
python hello.py
git status
git diff
git add .
git commit -m "feat: adding feature-1"
git push origin feature-1

Switch to main branch, merge changes of feature branch, check commit logs, set upstream branch, push and delete the branch from local and remote

git switch main
git merge feature-1
python hello.py
git log
git push --set-upstream origin main
git branch -vv
git branch -d feature-1
git push origin :feature-1

Lets repeat adding another feature and see some more options like amending a commit message, restoring files back to original changes, restoring files from staged area and reverting commits

git branch
git checkout -b feature-2
echo 'print("This is feature-2!")' >> hello.py
echo "Hey there" > README.md
python hello.py
git status
git restore README.md
git status
echo "Hey there" > README.md
git diff
git add .
git status
git restore --staged README.md
git restore README.md
git commit -m "feat: adding feature-1"
git commit --amend -m "feat: adding feature-2"
git push origin feature-2

Lets add a few commits and reset back to an older commit

for i in {1..5}; do echo $i >> README.md && git commit -am "feat adding commit $i"; done
cat README.md
git log
git reset HEAD~5
git log
cat README.md
git checkout README.md
for i in {1..5}; do echo $i >> README.md && git commit -am "feat adding commit $i"; done
cat README.md
git reset HEAD~5 --hard
cat README.md

# you can also do git reset COMMIT_ID

Lets merge feature 2 also to main

git branch
git checkout main
git merge feature-2
python hello.py
git log
git push origin main
git branch -d feature-2
git push origin :feature-2

Now feature 2 has introduced a bug in production. We need to revert it from main branch and fix the bug later.

python hello.py
git revert LATEST_COMMIT_ID
python hello.py
git push origin main
git checkout HEAD~1 -b feature-2-bugfix
python hello.py
sed -i 's/This is feature-2!/This is feature-2 fixed!/g' hello.py
git status
git diff
git commit -am "fix: feature-2 bug fix"
git push origin feature-2-bugfix

# You can replace HEAD~NUMBER with actual commit hash
# For macos use
# sed -i'.bak' -e 's/This is feature-2!/This is feature-2 fixed!/g' hello.py && rm hello.py.bak

Lets check the difference with main branch and try to do a merge

git log
git log main
git merge main

# Lets resolve the conflict manually by editing the file and removing unnessary lines

git add hello.py
git merge --continue
git log

At this point, we can see we are adding unnecessary merge commits. We should avoid this and instead do a rebase.
Lets repeat same merge operation again with an alternate command.
We will abort the merge and then look at rebase.

git reset HEAD~1 --hard
git log --oneline
git log main --oneline
git pull origin main
git merge --abort
git pull origin main --rebase

# Resolve the conflicts manually
git add .
git rebase --continue
git push origin feature-2-bugfix

Now raise a PR from feature-2-bugfix to main branch
Reveiw and Merge

Working with forks

Adding a remote repository as upstream, checking out the upstream branch and syncing with fork

git remote add upstream git@github.com:keshavprasadms/random-git-repo.git
git remote -v
git fetch upstream
git branch -a
git checkout -b remotes/upstream/main -b upstream-main
git branch -D main
git checkout -b remotes/upstream/main -b main

# Both the below commands do the same operation
# Push from one branch to another
git push origin upstream-main:main --force

# Force push
git push origin main --force

After force push we lost the latest commit that was introduced by the PR. So be careful in force push.
Lets take the missing commit to our branch and and push again Go to the closed PR and get the commit hash

git show COMMIT_HASH
git checkout main
git log --oneline
git pull origin main --rebase
git checkout COMMIT_HASH
git push origin main
git branch
git checkout -b missing-commit
git push origin missing-commit:main

Lets see how we can pick some specific commits

git checkout -b branch1
git checkout -b branch2
for i in {1..5}; do echo $i >> README.md && git commit -am "feat adding commit $i"; done
git log --oneline
git checkout branch1
git show FIRST_NEW_COMMIT_HASH
git cherry-pick FIRST_NEW_COMMIT_HASH

# If you pick random in between commits, you might get merge conflicts which you can resolve manually or abort using --abort option
# Lets also take rest of the commits

git cherry-pick FIRST_NEW_COMMIT_HASH..LAST_NEW_COMMIT_HASH

Lets see some interactive rebase

git checkout branch2
git push origin branch
git branch --set-upstream-to=origin/branch2 branch2
git rebase -i
git log --oneline
git rebase -i HEAD~5

# Use pick for first commits
# Use squash for all other commits
# Rewrite you commit message

Lets create some tags

git checkout main
git log --oneline
git tag v1.0.0
git show tags/v1.0.0
git push origin tags/v1.0.0

# Check tags on UI
git checkout COMMIT_HASH_OF_FEATURE_1
git tag v0.0.1
git push origin v0.0.1

# Check tags on UI

git tag -d v0.0.1
git push origin :tags/v0.0.1
git fetch upstream --tags

Remove files, stash file, pop files, grep files and blame

# Remove files
rm README.md
git status
git checkout .
git rm README.md
git status
git restore --staged .
git checkout .
rm README.md

# Stash and Pop files
echo "Hey" > README.md
git checkout branch1
git stash
git checkout branch1
git checkout main
git stash pop
git stash
echo "OK" > README.md
git stash
git stash list
git stash pop --index 2
git stash show -p stash@{0}

# Grep
git grep -i "hello"
git grep -iv "hello"

# Blame
git blame hello.py

Aliases

Set aliases as per your liking to blaze through the command line
Here are a few commonly used git alises

alias g='git'
alias ga='git add'
alias gb='git branch'
alias gc='git checkout'
alias gcp="git cherry-pick"
alias gca='git commit --amend  -S -s -m'
alias gcm='git commit -S -s -m'
alias gd='git diff'
alias gfa='git fetch --all'
alias gl='git log'
alias glo='git log --graph --pretty=oneline --abbrev-commit'
alias gpl='git pull --rebase'
alias gplo='git pull --rebase origin heads/$(git rev-parse --abbrev-ref HEAD | rev | cut -d / -f1 | rev)'
alias gplu='git pull --rebase upstream heads/$(git rev-parse --abbrev-ref HEAD | rev | cut -d / -f1 | rev)'
alias gpo='git push origin $(git rev-parse --abbrev-ref HEAD)'
alias gpu='git push upstream $(git rev-parse --abbrev-ref HEAD)'
alias grb='git rebase'
alias grc='git rebase --continue'
alias grs='git rebase --skip'
alias gs='git status'
alias gst='git stash'
alias gstp='git stash pop'

Sign your commits

Signing your commits is always a good practice as it proves your identity
Follow below steps to setup signing of commits

gpg --version
# >= 2.1.17
gpg --full-generate-key

# < 2.1.17
gpg --default-new-key-algo rsa4096 --gen-key

# Enter your details
gpg --list-secret-keys --keyid-format=long

# Get the key id by looking at sec field and after /
gpg --armor --export 3AA5C34371567BD2

Copy your GPG key, beginning with -----BEGIN PGP PUBLIC KEY BLOCK----- and ending with -----END PGP PUBLIC KEY BLOCK-----
Add the key here
If any issues, read this doc

Raising PR using hub

Install hub and check it out
Here is a sample

hub pull-request -b USERNAME_OR_ORGANISATION/REPOSITORY_NAME:BRANCH -m "title: text" -m "description: text"

Example

hub pull-request -b keshavprasadms/git-training:main -m "Git training notes" -m "feat: adding training notes"

Using git on SSH

echo 'ssh-add -k ~/.ssh/id_ed25519' >> ~/.bashrc
source ~/.bashrc

# Remove the GITHUB_TOKEN environment variable and use ssh going forward

abhijithk666 / git-training

git-training

Two factor Authentication

Using Git via SSH and HTTPS

Create an API Token

Setup an ssh key

`gh` command line

Git commands

Working with forks

Aliases

Sign your commits

Raising PR using hub

Using git on SSH

Further Exploration

About

git-training

Two factor Authentication

Using Git via SSH and HTTPS

Create an API Token

Setup an ssh key

gh command line

Git commands

Working with forks

Aliases

Sign your commits

Raising PR using hub

Using git on SSH

Further Exploration

About

`gh` command line