Git Reference

Quick reference for Git

This page describes common Git commands that I have encountered in my personal coding projects. It it written as a reference, but by no means a comprehensive reference.

Configuration

You can edit a git configuration either from the command line or edit a .gitconfig that lives in your home directory.

Command Line Entry

To edit a parameter from the command line that will edit your git config file, run a command in the following format:

git config --global <section>.<key> <value>

For instance, if you would like to edit the user name for all commits made from an account, run the command:

git config --global user.name "Your Name"

Similarly, if you would like to change the default name to main (instead of the usual default master) run the following command:

git config --global init.defaultBranch main

.gitconfig file

The .gitconfig file lives in your home directory, or is created upon the first run of a git config command. It takes the format”

[section0]
    key = value

[section1]
    key = value

Submodules

Add Submodule

To add a submodule, first add the repository in the web interface of your Git remote host, e.g. GitHub or Azure DevOps.

In the repository that you would like to use to contain the submodule, use the following command:

git submodule add <submodule address>

E.g.

git submodule add git@github.com:rebeccajr/test-submodule.git

Initialization

When first adding a submodule, or when cloning a repository with submodules you must run:

git submodule update --init --recursive

Note The --recursive flag is only necessary if there are nested submodules, however it won’t hurt anything if there aren’t nested submodules.

Update Submodule

After the initialization of a submodule, to simply update that submodule, i.e. pull down any new commits, run:

git submodule update --recursive

SSH Key Setup

To enable seamless authentication for Git without repeating logins, follow these steps to configure SSH keys. This guide covers setup for both GitHub and Azure DevOps.

GitHub

The following information was taken from the following source:

GitHub SSH Key Setup Reource

1. Generate an SSH key.

   ssh-keygen -t ed25519 -C "email@address.com"

   Output

   Generating public/private ed25519 key pair.

2. Hit enter after each of the following prompts.

   Enter file in which to save the key (/home/<user_name>/.ssh/id_ed25519):
   Enter passphrase (empty for no passphrase):
   Enter same passphrase again:

   Output

   Your identification has been saved in /home/<user_name>/.ssh/id_ed25519
   Your public key has been saved in /home/<user_name>/.ssh/id_ed25519.pub
   The key fingerprint is:
   ################################################## email@address.com
   The key's randomart image is:
   +--[ED25519 256]--+
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   +----[SHA256]-----+

3. Start the SSH Agent in the background.

   eval "$(ssh-agent -s)"

   Output

   Agent pid 59566

4. Register your private SSH key with the SSH Agent.

   ssh-add ~/.ssh/id_ed25519

   Output

   Identity added: /home/flux/.ssh/id_ed25519 (email@address.com)

5. Go to settings.

   

6. Go to SSH keys.

   

7. Click New SSH key button.

   

Azure DevOps

The following information was taken from the following source:

Azure DevOps Key Setup Reource

1. Generate an SSH key.

   ssh-keygen -m PEM -t rsa -b 4096

   Output

   Generating public/private rsa key pair.

2. Hit enter after each of the following prompts.

   Enter file in which to save the key (/home/<user_name>/.ssh/id_rsa): (hit enter)
   Enter passphrase (empty for no passphrase): (hit enter)
   Enter same passphrase again: (hit enter)

   Output

   Your identification has been saved in /home/<user_name>/.ssh/id_rsa
   Your public key has been saved in /home/<user_name>/.ssh/id_rsa.pub
   The key fingerprint is:
   SHA256:########################################### user@computer
   The key's randomart image is:
   +---[RSA 4096]----+
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   |   ###########   |
   +----[SHA256]-----+

3. Start the SSH Agent in the background.

   eval "$(ssh-agent -s)"

   Output

   Agent pid 12956

4. From Azure DevOps web interface