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Debug Academy - Git

The free lesson you are reading is provided by Debug Academy. DebugAcademy offers career-changing, in-person, web development training in the Northern VA & Greater Washington D.C. area. Our primary focus is in Drupal, and our curriculum is entirely assembled by a certified Drupal Grand Master and employee of Acquia. Visit DebugAcademy.com for more information.

This lesson is a subset of one of Debug Academy's git lessons.

Git is a Version Control System, or 'VCS'. It takes snapshots of the state of files when changes are made. It is extremely beneficial and necessary on any large software project. It is a red flag if a software development company is not enforcing the use of version control.

A practice assignment can be found in the repository under the name: git_assignment.md

Git Installation

Mac OS X

Mac Option 1 (Recommended)

Download Xcode from the Mac App Store. There is a program on your computer named 'App store' which you use to download Xcode.

Mac Option 2 (If harddrive space is limited)

If you do not want to download Xcode due to its large file size, try this instead:
https://git-scm.com/download/mac

Windows

Use Git for Windows ( https://git-for-windows.github.io/ ) (command line).

Ubuntu

Use the command sudo apt-get install git-core to install Git using the command line.

Follow the installation options that will be presented to you.

Post-Installation Setup

Git keeps track of the history of files changed - including who made each change. Because of which, you are required to configure your name and e-mail address.

To configure your name and e-mail address, enter the following 2 commands into the command line where you will be using git:
git config --global user.name "YOUR NAME"
git config --global user.email "YOUR EMAIL ADDRESS"

Command line basics

If you are new to programming, you likely spend most of your computer-time using a GUI (pronounced gooey). A GUI is a user interface designed to hide the complexity behind applications. We will be using the terminal for portions of this Git lesson.

Below you will find a subset of Debug Academy's command line basics lesson.

ls

Lists files and folders in the current directory.

Detail

  • Command: ls
  • Stands for: List
  • Basic usage: ls
  • Common Flags: To use flags, write a single dash, followed by each flag, with no spaces in-between the dash and each flag.
    • l Show detailed information, including filesize and permissions
    • a List all files, including hidden files
    • h Display output (such as filesize) in a human-friendly format
  • Advanced Usage: ls [specific file or folder] -lah
  • Typical frequency: > Daily
  • Example: ls sites/all/modules -lah

cd [relative path to folder]

Used for navigating to other folders.

Detail

  • Command: cd
  • Stands for: Change directory
  • Basic usage: cd [relative or absolute folder name]
  • Advanced Usage:
    • cd ../ navigate up 1 level from the current directory
    • cd ../../ navigate up 2 levels from the current directory
    • cd sites navigate to the 'sites' folder within the current directory using relative path (path does not begin with a slash)
      • If the sites folder is within my current folder, I can use this relative path.
    • cd /Users/ashraf/sites navigate to the 'sites' folder within the user's home directory using absolute (entire) path
      • Using the absolute (entire) path, I can jump to the sites folder from whereever I am
  • Typical frequency: > Daily
  • Examples: cd ~/Desktop/debugacademy

* (asterisks)

  • Asterisks means 'anything'.
  • In many commands, can be used as part of a filename to expand the command. For example:
  • Can be used to select all files in a folder
  • mv files/* files/ashraf/
  • Can be used to move files based on a partial filename
  • mv files/*.pdf files/ashraf/
    • This moved everything in the 'files' folder whose name ends in '.pdf'.
  • mv files/a* files/ashraf/
    • This moved everything in the 'files' folder whose name starts with 'a'.
  • mv files/*tmp* files/trash
    • This moved everything in the 'files' folder whose name contains 'tmp'.

../

  • Used to denote 'up one level'
  • To change to the directory 'up one level':
    • cd ../
  • Can be combined to go up multiple levels:
    • cd ../../
    • That takes you up two levels

./

  • Used to denote 'current directory'
  • Example: mv files/file1.html ./
    • We moved a file from the 'files' folder into the folder we are currently in.

Git commands

Below is a subset of the Debug Academy lesson on git commands. It covers the commands we will be using throughout this assignment.

git init

Creates a new git repository for the first time. This is done by adding the hidden .git/ directory to the current folder.

Detail

  • Command: git init
  • Stands for: Initiate git repository
  • Basic usage: git init
  • Typical frequency: < Once a month
    Example:
cd sites/new-site  
git init  
touch README.md
git add README.md
git commit -m "My repository's first commit"

Now sites/new-site is a git repository, and it has one commit.

git clone [URL] [destination-name]

Copies (aka clones) a git repository and all of its contents from a specified URL to your computer.

Detail

  • Command: git clone
  • Stands for: Clone a git repository
  • Basic usage: git clone [URL] [Destination]
  • Typical frequency: < Weekly
  • Example: git clone https://github.com/debugacademy/course-drupal.git DA-drupal-course
    • That command copied the entire course-drupal repository (folder, subfolders, and files) into a folder named 'DA-drupal-course'

git add [file or folder]

Stages files for inclusion in your next commit. When you commit files, only the staged files will be included in your commit. Changes to files that were not 'add'ed will remain untracked by git.

Filenames must be typed exactly and with extensions.

Detail

  • Command: git add
  • Stands for: Add files to the next commit
  • Basic usage: git add [file or folder]
  • Common Flags: To use flags, write a single dash, followed by each flag, with no spaces in-between the dash and each flag.
    • --all Stages file additions and removals for next commit. Includes all files
    • -p Allows you to interactively choose portions of files to be 'git add'ed, as opposed to blindly git add'ing an entire file
  • Typical frequency: > Daily
  • Example:
    • git add sites/all/modules/views
    • git add assignment1.md
    • git add -p assignment1.md

git commit -m "[message]":

Stores the current version of all files that were added (staged) using 'git add'.

  • There should be a commit for every meaningful change.
  • There should be a short message describing what each commit is for.

Detail

  • Command: git commit
  • Stands for: Commit files and/or folders to the git repository
  • Basic usage: git commit -m '[message]'
  • Common Flags: To use flags, write a single dash, followed by each flag, with no spaces in-between the dash and each flag.
    • m Pass the commit's message as an argument. Must be followed by a space, then a short string (words) in quotations.
  • Advanced Usage: git commit -m '[message]'
  • Typical frequency: > Daily
  • Example:
    • git add sites/all/modules/views/
    • git commit -m 'Added views module to repository'

git checkout [branch]

Switches to the specified branch. This causes files on the current branch to be 'hidden' elsewhere, and files on the branch you are switching to to appear in the repository.

Detail

  • Command: git checkout [branch]
  • Stands for: Check out (go to) the branch named [branch]
  • Basic usage: git checkout [branch]
  • Typical frequency: > Daily
  • Example:
    • git checkout sitename-IssueNumber (now we are taken to the branch named sitename-IssueNumber, if it exists)

git checkout -b [new-branch] [branch]

Creates a new branch named [new-branch], which initially matches the branch named [branch] exactly.

Detail

  • Command: git checkout -b [new-branch] [branch]
  • Stands for: Create the branch [new-branch] to match the branch named [branch], then check out [new-branch]
  • Basic usage: git checkout -b [new-branch] [branch]
  • Typical frequency: > Daily
  • Example:
    • git checkout -b challies-435 master
      • This creates a branch named 'challies-435' based off of the master branch
      • It then Checks out the new branch named challies-435

git remote add [alias] [url]

Adds a remote connection to a repository, which you can then push to or pull from. This is analogous to adding a contact to your phone's contact list which you can then call.

Detail

  • Command: git remote add [alias] [url]
  • Stands for: Add an alias for interacting with a remote repostory.
  • Basic usage: git remote add [alias] [url]
  • Typical frequency: > Monthly
  • Example:
    • git remote add debugacademy https://github.com/debugacademy/course-drupal.git
      • Now we are connected to (can pull from) the 'debugacademy/course-drupal' repo.
      • If we have the right privileges, we can also now push to the 'debugacademy/course-drupal' repo.
      • e.g. git pull debugacademy master ## this command will now automatically pull from debugacademy/course-drupal.git

git remote

Shows the aliases, or nicknames, of the remote repositories whose URLs are referenced in your repository.

Detail

git branch

Lists the branches that are on your computer. It places an asterisk next to the branch you are on.

Detail

  • Command: git branch
  • Stands for: List the branches in your git repository
  • Basic usage: git branch
  • Common Flags: To use flags, write a single dash, followed by each flag, with no spaces in-between the dash and each flag.
    • --all Multiple character flag, so preceded by 2 dashes instead of 1
      • Lists all branches you have downloaded (fetched), including remote branches
  • Typical frequency: > Daily
  • Example: git branch

git push [remote alias] [local branch being pushed]

Used for sending commits from [branch] to [remote]/[same branch]. Sends ALL committed work on [branch you are pushing].

Detail

  • Command: git push
  • Stands for: Push a specific branch from my repository to the specified remote.
  • Basic usage: git push [remote alias] [local branch being pushed]
  • Typical frequency: > Daily
  • Example: git push myremote assignment2

git fetch --all

Downloads ('fetches') all branches and tags from all connected remotes. Downloaded branches are saved locally with the following name structure: [remote alias]/[remote branch name]

Detail

  • Command: git fetch --all
  • Stands for: Fetch (download) all branches from connected remotes
  • Basic usage: git fetch --all
  • Typical frequency: > Daily
  • Example:
    • git fetch --all
      • Downloaded branches are listed upon downloading
      • Entire name (including [remote alias]/) must be used for any interaction with fetched branches
    • 'Fetched' branches are not displayed by the git branch command
      • To display fetched branches as well, run git branch --all
      • Fetched branches will be displayed as: remotes/[remote alias]/[branch name]
      • Do not include the remotes/ portion of the name when interacting with the branch

git merge [branch name]

Merges work from [branch name] into the branch you currently have checked out.

Detail

  • Command: git merge [branch name]
  • Stands for: Merge commits from the specified branch into the currently checked-out branch
  • Basic usage: git merge [branch name]
  • Typical frequency: > Daily
  • Examples:
    • If I have branch2 and branch4 in my local repository and I want to bring the changes from branch4 into branch2:
      • git checkout branch2
      • git merge branch4
    • If it says 'merge conflict', that means the two branches make changes to the same section of the same file
      • Git will insert the changes from BOTH branches in the file
      • Git will insert <<< within the file(s), before each conflict
      • Git will insert >>> within the file(s), after each conflict
      • It is your job to review what git has added to the files, then to remove what you do not want. Such as '<<<' and '>>>'.
      • After resolving the conflict, it is your job to add and commit your changes.
      • Following git workflows such as 'git flow' minimize messy merge conflicts.

git pull [remote] [branch name]

Immediately and automatically merges all new changes from [branch name] on [remote] to the branch you currently have checked out. When you git pull, make sure you have the branch you want to merge work into already checked out

Detail

  • Command: git pull [remote] [branch name]
  • Stands for: Pull (Fetch and then merge) work from [branch name] on [remote]
  • Basic usage: git pull [remote] [branch name]
  • Typical frequency: > Daily
  • Example:
    • For example, if I want to pull from debugacademy's 'master' branch into my 'branch2' branch
      • git checkout branch2
      • git pull debugacademy master

Good to know

Help! My command line is stuck.

Sometimes, especially after a git merge or git commit, people find themselves seeing a bunch of text but being unable to type. If this happened to you, you likely are seeing the text editor 'vim'.

vim is a popular, advanced command line editor.

  • Press escape to prepare for the subsequent commands
  • To enable typing, press i for 'Insert'
  • To save the file, press 'escape', then :, then w (for write), then ENTER
  • To exit a file and leave vim, press 'escape', then :, then q (for quit), then ENTER
    • You may need to press y if you have unsaved changed