Debug Academy - Git

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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

Use the Git OS X Installer ( http://code.google.com/p/git-osx-installer/ ). If you use the Homebrew package manager, run brew install git. You might want to install GitX (GUI).

Windows

Use Git for Windows ( http://msysgit.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

• ls => 'list'
• Lists files and folders in the current directory

cd [relative path to folder]

• 'cd' = >'Change Directory'
• Used for navigating to other folders
• Can use an absolute (entire) path: cd /Users/ashraf/Desktop/debugsociety/subfolder-name
• Absolute paths begin with a /
• Can use a relative path:
• cd /Users/ashraf/Desktop
  • Used an absolute path to get to the Desktop folder
• cd debugsociety
  • Because the debugsociety folder is within my current folder, I can use a relative path.
• cd subfolder-name
  • Because subfolder-name is in my current folder, I can use a relative path.

* (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:

• For creating a new git repository.
• It turns the current directory into a git repository.
• For example:
  • 'cd' into a non-git folder.
  • Type 'git init'.
  • Now the folder is a git repository.

git clone [URL] [destination-name]:

• For copying (aka cloning) a repo (and all files in it) from a URL to your computer.
• For example:
  • "git clone https://github.com/debugacademy/debugacademy-git.git da-git"
  • That will download a copy of the entire debugacademy-git repository into a local folder (on your computer) called 'da-git'

git add [file or folder]:

• Includes the 'add'ed files in your next commit.
• Changes to files that were not 'add'ed will remain untracked by git.
• Filenames must be typed exactly and with extensions.
  • For example, if you want to add a file named File1.html to your next commit:
  • git add File1.html will work.
    • 'git add File1' will NOT work.
    • 'git add file1.html' will NOT work.

git commit -m "[message]":

• Stores the current version of all files that were added using 'git add'.
• There should be a commit for every meaningful change.
• There should be a short message describing what the commit is for.
  • For example: git commit -m "Updated git_commands.md"
• If this message displayed: no changes added to commit, it means you did not 'git add' your changes before committing them.

git checkout [branch] :

• Used to switch branches.
  • For example:
    • I am on the 'master' branch
    • git checkout hello-world
    • If it exists, I am taken to the branch named 'hello-world'

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

• Used to create a new branch named [new-branch], which initially matches the branch named [branch] exactly
  • For example:
    • git checkout -b my-branch master
    • The branch 'my-branch' is created based off of the 'master' branch
    • Then I am taken to the new 'my-branch' branch

git remote add [alias] [url]:

• Adds a remote connection to a repository.
• For example:
  • git remote add ds https://github.com/debugacademy/debugacademy-git.git
  • Now we are connected to (can pull from) the 'debugacademy/debugacademy-git' repo.
    • If we have the right privileges, we can also now push to the 'debugacademy/debugacademy-git' repo.
  • i.e. git pull ds master ## this command will now automatically pull from debugacademy/debugacademy-git.git

git remote:

• Shows the nicknames of the remote repositories that your repo is connected to.
  • For example:
  • git remote might display:
    • origin
    • ds
• Passing the -v flag shows more detail.
  • For example:
  • git remote -v might display:
    • da https://github.com/debugacademy/debugacademy-git.git (fetch)
    • da https://github.com/debugacademy/debugacademy-git.git (push)
    • origin https://github.com/[YOUR-USERNAME]/debugacademy-git.git (fetch)
    • origin https://github.com/[YOUR-USERNAME]/debugacademy-git.git (push)

git branch:

• Shows you the branches on your computer
• Places an asterisk next to the branch you are on.

git push [remote] [branch you are pushing]:

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

git pull [remote] [branch name]:

• Immediately/automatically merges all new changes from [remote]/[branch name] to the branch you currently have checked out.
• When you git pull, make sure you have the branch you want to pull into checked out
• For example, if I want to pull from debugacademy's 'master' branch into my 'branch2' branch
  • git checkout branch2
  • git pull debugacademy master

git merge [branch name]:

• Merges work from [branch name] into the branch you currently have checked out.
• For example, 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.

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.

• 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