A quick Git tutorial and cheatsheet

Connecting to github requires generation of SSH keys.

# Email needs to be same as the login of your github account
ssh-keygen -t rs -b 4096 -C "<email>"

• The above command generates a key in the current directory.
• Move the keys to the /home//.ssh directory
• add the private key to the registry using the following command

ssh-add <private-key>

• add the public key to the github account

• Write code
• Stage changes (git add)
• Commit changes (git commit)
• Push changes (git push)
• Create a PR

Install git with the instructions provided on the URL

git --version

git init
git add README.md
git commit -m "First Commit"
git remote add origin <origin-name>
git push -u origin master

git clone <repo-url>
git add README.md
git commit -m "First Commit"
git remote add origin <origin-name>
git push -u origin master

git status

• Untracked file - newly added file which git does not know about
• Modified file - added file which has been modified

# Adds only one file untracked/modified
git add <file-name>

# Add all files which are untracked/modified
git add .

git commit -m <description of commit>

# This command only commits the file changes
git commit -m <description of commit>

# This command adds and commits the changes
git commit -am <description of commit>

git remote -v

git checkout -b <branch-name>

git checkout <branch-name>

git diff

git diff <branch-name>

git merge <branch-name>

you will need to stash changes

git merge <branch-name>

#Resets the specific file
git reset <filename>

#Resets all the files
git reset --hard 

#Resetting your last commit
#Tilda here means 1 behind head
git reset HEAD~1

# resetting it to be a previous commit
git reset --hard <SHA>

# Displays all information
git log

# Displays only one line information
git log --oneline

• Change a commits message
• Delete commits
• Reorder commits
• Combine multiple commits into one
• edit/split an existing commit into mutiple new commits

• Do not use interactive rebase on commits you have already pushed to a shared remote repository.

• To be used only for cleaning up a local commit history before merging it into shared team branch.

• How far do you go back to consolidate commits?

git rebase -i HEAD~<no-behind>

• Executing the above command should open up an editor
• If you need to update a commit, mark "pick" as "reword". Close the editor
• This should open an another editor to change the comment, save and close

• Executing the above command should open up an editor
• If you need to update a commit, mark "pick" as "reword". Close the editor
• This should open an another editor to change the comment, save and close

• Follow the same steps as above except that we rename "pick" to "squash"

Allows individual commits to be integrated

git cherry-pick <SHA>

What happens when you want to move back a few commits and delete the commit. After deleting you realize you have some vital changes which you want to retrieve back

Move back the commits on a particular branch

git checkout <branch-name>
git reset --hard <SHA>

After the above command you will notice that the pointer has moved back a few commits. The changes no longer show up when the following command is executed

git log

Assume there are some important changes you want to get back. Execute the following command to understand which changes you want back

# Display all the logs
git reflog

There are 2 ways to reset it

git reset --hard <revision-SHA>

or

# create a branch
git branch <branch-name> <revision-SHA>

• Delete a branch by mistake
• Recover the branch

git reflog
git branch <same-branch-name-as-deleted> <release-SHA>

Consider a git repository on your local machine, let us say you want to add another submodule to this parent rep from another repo.

git submodule add <url>

This should add a .gitmodules folder in the parent project and an entry into the .git/config folder.

git status

Performing a git status basically shows that there are files to be staged. We go ahead and commit the files

Instead of using the submodule commands let us say we clone another repo into a parent repo, and assume that the project by itself which you are cloning has submodules, in that case the "git clone" will result in empty directories. This should clone automatically all the submodules.

git submodule update --init --recursive

You can use the above or you can use clone with the following command

git clone --recurse-submodules <url>

Filtering commit history can be odne by the following criteria

#by Date  --before / --after
git log --after=<date> --before=<date>

#by message
git log | grep "<string>"

#by author
git log --author=""

#by file -- <filename>
git log -- <filename>

#by branch <branch-name>
git log <branch-name>

• https://www.youtube.com/watch?v=RGOj5yH7evk
• https://askubuntu.com/questions/730754/how-do-i-show-the-git-branch-with-colours-in-bash-prompt