Introduction

This repo has been prepared as the platform to practice git commands.

It is perfectly ok to break things.

Pre-requisite

• Check to see if you have git installed: https://github.com/git-guides/install-git
• Although not required, it is recommended to enable SSH authentication: https://docs.github.com/en/authentication/connecting-to-github-with-ssh/adding-a-new-ssh-key-to-your-github-account

Git architecture

Essential git commands and techniques

Basic

First step

• clone

  Use this command to clone an existing repo. To clone this repo,

  git clone https://github.com/CADWRDeltaModeling/test.git

  To change the name of the directory (e.g., "github_exercises"),

  git clone https://github.com/CADWRDeltaModeling/test.git github_exercises

• init

  Use this to create a new git repo. For example, running git init will make the current directory a git repo.

• status

  This shows the status of the local repo - any changes, what have been staged, etc.

  Frequently used options:

  -s

  -u[mode]: Specifies what is displayed under "Untracked files". -u must be followed by one of the following modes without any space (e.g., git status -uno):

  • no: Hides untracked files.
  • all: Shows all untracked files. Same as running git status -u.
  • normal: Shows untracked files and the names of directories that contain untracked files (without the contents therein). Same as running git status (without the -u option).

  Note: git tracks files, not directories. Thus, empty directories will never show up with `git status`
  

• add

  This command stages the changes that have occurred in the local repo (modifying what is inside a file, creating a new file, removing an exsting file, etc. ).

  Frequently used options:

  -i: Enters interactive mode. Here, user can select deisred commands step by step.

  -p: Pick and choose different edits and files

• commit

  Commits currently staged changes.

  Frequently used options:

  -m: Used as in git commit -m "Introduce a new variable x", this option lets users to provide the commit message directly (as opposed to entering it on the default text editor)

  --amend: When git commit --amend is run, user can change the last commit message.

• push

  Pushes all commited changes to the remote repo.

• pull

  Fetches new commits from the remote repo then merges them into the local (same thing as doing git fetch then git merge).

  Frequently used options:

  --rebase (strongly recommended to use whenver doing git pull): Fetches new commits from the remote, then combines them with any local changes without merging, thus creating a clean, linear history.

• reset

  Undos commits that have not been pushed to the remote repo.

  Frequently used options:

  --soft: Only moves the HEAD, and all commited changes are saved.

  --mixed: Moves the HEAD and and unstages changes, but the working directory is NOT modified. Default behavior of git reset (used without options)

  --hard: The working directory becomes exactly the selected commit. To undo, run git reflog to identify the point to which you want to go back, then run git reset followed by the reference hash.

Making and undoing changes

• mv: Renames or moves a file then automatically stages the changes.

• rm: Removes a file then automatically stages the changes.

• restore: Discards uncommited changes.

• stash: Temporarily shelves the local changes to be used later.

  Use example:

  1. Run git stash to shelve local changes.
  2. Run git stash list to look at the list of stashes.
  3. Run git stash apply followed by the stash hash to bring back the desired changes.
  4. Run git stash pop applies and removes the stash.

• tag: Marks specific commits.

  Use example:

  1. Run git tag v1 to mark the current commit as "v1"
  2. Run git tag to see list of existing tags
  3. Run git show v1 to see what the tagged commit changed. If a message was included when tagging (e.g., git tag -a v1 -m "Prototype done"), then the message will also be shown.

Versioning

• branch
• checkout
• track
• update

Making collaboration smooth

• fork
• pull request

Intermediate

rebase

• squash
• reorder
• delete

merge

rebase vs. merge

conflict resolution

Conflict resolution is confusing in vscode so might be simpler to do via plain text editor Look for

<<<<<<
some words here
======
some other words here
>>>>>>

Resolve the above by choosing any combination of the text between <<<<< and >>>>> and then removing those special markers <<<<<<<<, =========, >>>>>>>> once done

E.g. I typed in whatever content and replaced the special markers

some words here with other words that are upto me

Make sure to verify that there are no other conflict blocks (with those special symbols anywhere else)

Then add the modified file and commit as usual to resolve the merge.

Advanced

Best practices

Bad practices