Git + linux cheatsheet

Cheatsheet: Git Commands, SSH Key Management, and Clipboard Operations

Git Commands: Moving Changes to a New Branch

1. Check Current Branch:

   git branch

2. Create and Switch to a New Branch:

   git checkout -b new-branch-name

3. Stage Changes:

   git add .

4. Commit Changes:

   git commit -m "Commit message"

5. Push Changes to New Branch:

   git push origin new-branch-name

6. Switch Back to the Original Branch:

   git checkout original-branch-name

7. Update Original Branch with Remote Changes:

   git fetch origin
   git reset --hard origin/original-branch-name

Rebase vs. Merge

• Rebase:

  • Reapplies changes on top of another branch.
  • Cleaner, linear history but rewrites commit history.
  • Command: git rebase branch-name

• Merge:

  • Combines changes from one branch into another.
  • Maintains history of both branches, creates a merge commit.
  • Command: git merge branch-name

SSH Key Management

1. Install OpenSSH Server (if not installed):

   sudo apt update
   sudo apt install openssh-server

2. Enable SSH Service to Start on Boot:

   sudo systemctl enable ssh

3. Start SSH Service Immediately:

   sudo systemctl start ssh

4. Verify SSH Service Status:

   sudo systemctl status ssh

5. Copy Public Key to Server (using ssh-copy-id):

   ssh-copy-id username@server-ip

6. Manually Add Public Key to authorized_keys:

   • Connect to server:

     ssh username@server-ip

   • Create .ssh directory:

     mkdir -p ~/.ssh
     chmod 700 ~/.ssh

   • Add public key:

     nano ~/.ssh/authorized_keys

   • Set permissions:

     chmod 600 ~/.ssh/authorized_keys
     chown username:username ~/.ssh
     chown username:username ~/.ssh/authorized_keys

7. Test SSH Connection to GitHub:

   ssh -T git@github.com

8. Check and Update Remote URL:

   git remote -v
   git remote set-url origin git@github.com:username/repository.git

Clipboard Operations

1. Install xclip:

   sudo apt update
   sudo apt install xclip

2. Install xsel:

   sudo apt update
   sudo apt install xsel

3. Copy File Contents to Clipboard:

   • Using xclip:

     xclip -sel clip < filename

   • Using xsel:

     xsel --clipboard < filename

4. Extract and Clean Public SSH Key:

   • Using awk:

     awk '{print $2}' ~/.ssh/id_rsa.pub

   • Using sed:

     sed 's/^[ \t]*//;s/[ \t]*$//' ~/.ssh/id_rsa.pub

   • Using cut:

     cut -d ' ' -f 2 ~/.ssh/id_rsa.pub

   • Using tr:

     tr -d ' ' < ~/.ssh/id_rsa.pub

5. Copy Cleaned Key to Clipboard:

   • Using xclip:

     awk '{print $2}' ~/.ssh/id_rsa.pub | xclip -sel clip

   • Using xsel:

     awk '{print $2}' ~/.ssh/id_rsa.pub | xsel --clipboard

6. Paste Key in Terminal:

   • Use Ctrl + V or Shift + Insert.

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This cheatsheet covers Git branching and remote operations, managing SSH keys, and clipboard operations on Ubuntu.