Git setup in 5 minutes

I've had these notes regarding git setup in Linux for a while and decided it would be good to add it to the blog for future reference. Setting up git and SSH is a little tricky. For example, if you don't have all the file permissions just right for your SSH setup, things will just not work. Setup involves piecing together information from multiple web searches, so collecting it all here is useful.

Some of the notes also explain how you can copy git and SSH configurations from Windows to a Linux VM (e.g. WSL2 or VirtualBox-based).

Installation

Install git. Note that gitk is optional. I like gitk for quickly reviewing the changes from each commit in a file.

• Install git and gitk:

sudo apt update
sudo apt upgrade
sudo apt install git gitk

• If you already use git on Windows, you can find your config file and keys from there. On Windows, you can get to the .ssh folder using cd %homedrive%%homepath%\.ssh from a command prompt.

SSH Setup

• Create folder for SSH setup:

mkdir -p ~/.ssh
chmod 700 ~/.ssh
cd ~/.ssh
nano config  # create git config file

• Save the following in a file named ~/.ssh/config:

Host github.com
  User git
  Hostname github.com
  PreferredAuthentications publickey
  IdentityFile ~/.ssh/github_id_rsa

• I'm assuming you already have private and public SSH keys named github_id_rsa and github_id_rsa.pub for your GitHub account. If not, create them (e.g. see here).

• Copy github_id_rsa and github_id_rsa.pub into ~/.ssh.

• Set the appropriate file permissions:

cd ~/.ssh
cp /media/sf_sharelinux/github_id_rsa .
cp /media/sf_sharelinux/github_id_rsa.pub .
touch authorized_keys
touch known_hosts

chmod 600 github_id_rsa
chmod 644 github_id_rsa.pub
chmod 644 config
chmod 644 authorized_keys
chmod 644 known_hosts

• Verify that the files and ownership are similar to the following:

rc@bb:~/.ssh$ ll
total 20
drwx------  2 rc rc 4096 Nov 23 13:54 ./
drwxr-xr-x 16 rc rc 4096 Nov 23 13:17 ../
-rw-r--r--  1 rc rc    0 Nov 23 13:54 authorized_keys
-rw-r--r--  1 rc rc  122 Nov 23 13:22 config
-rw-------  1 rc rc 1675 Nov 23 13:54 github_id_rsa
-rw-r--r--  1 rc rc  401 Nov 23 13:54 github_id_rsa.pub
-rw-r--r--  1 rc rc    0 Nov 23 13:54 known_hosts

• If the user and group don't both match your username, use chown to set them that way, e.g. chown rc.rc filename

Git Configuration

• If you already have .gitconfig under Windows (in the %homedrive%%homepath% folder), you can copy it into the Linux home directory. Alternatively, set up the username and email for git as follows. Note that the no-reply email is used (which can be configured in GitHub):

git config --global user.email 48181110+ravi-chandran@users.noreply.github.com
git config --global user.name ravi-chandran

• You can check your git configuration, especially any non-global options with:

git config --list --show-origin

Verify Setup

• Verify SSH connection to GitHub with ssh -T git@github.com which should respond with a success message.

• Additional checks: Clone a repository to verify configuration. Verify that you can push as well.