the command line
Objectives
- Define what the command line is
- Learn command line navigation and file structure
- Learn to manipulate files and folders via command line
The command line (or terminal) is a faster and more powerful way to maneuver your operating system than by using a GUI (graphical user interface), such as Windows Explorer or Mac Finder.
Use special keywords to do everything you can with a GUI and more.
What the Command Line Does
sed 's/dude/Colt/g' report.txt > report_new.txt
How we'll use it
We will use the terminal to:
- navigate around
- create and remove directories and files
- move, copy, and paste things
- use version control (git) to keep track of changes
- Later, execute Python scripts
INSTALLATION TIME
It's actually not that bad!
Option 1: Mac
Option 2: PC
Option 3: Cloud9
There's a
video for that!
There's a
video for that!
There's a
video for that!
🍏
💻
☁️
(for once)
MAC INSTALLATION
PC INSTALLATION
Cloud9
INSTALLATION
OS File Structure
Operating Systems organize their folders in a hierarchy (a tree) with parents and children, all relative to a base root directory.
root /
tmp
Users
Colt
...
Files and directories have absolute paths based on the root, where each additional level down adds a " /".
/Users/Colt
The absolute path for "Colt" is:
Where am I?
The green directory below is a special directory called "home", which is also known as "~". This is the default directory upon opening your terminal.
root /
tmp
Users
Colt ~
...
How do I find out where I am?
The command "pwd" (print working directory) will tell you the full absolute path of where you're at!
root /
tmp
Users
Colt ~
...
stuff
pwd
/Users/Colt/stuff
Navigating Absolutely
The command "cd" ( "change directory") followed by the absolute path of the folder will navigate you directly there.
root /
tmp
Users
Colt ~
...
stuff
pwd
/Users/Colt/stuff
cd /Users
pwd
/Users
Navigating Relatively
The dot "." stands for current directory, and dot-dot ".." stands for parent directory. This allows for relative navigation:
root /
tmp
Users
Colt ~
...
stuff
pwd
cd ..
pwd
/Users/Colt/stuff
/Users/Colt
What's Inside?
The keyword "ls" will "list" the contents of a directory. You can supply options such as "-a" to list all files (including hidden ones), or "-l" for a longer format.
total 136
drwxr-xr-x+ 42 csteele staff 1428 Oct 3 10:10 .
drwxr-xr-x 5 root admin 170 Sep 20 13:10 ..
drwx------ 5 csteele staff 170 Oct 2 10:28 .Trash
-rw------- 1 csteele staff 7538 Oct 2 10:29 .bash_history
-rw-r--r-- 1 csteele staff 769 Sep 24 17:06 .bash_profile
-rw------- 1 csteele staff 7 Sep 20 13:51 .python_history
drwx------@ 4 csteele staff 136 Sep 20 13:27 Applications
drwx------+ 10 csteele staff 340 Oct 2 10:37 Desktop
drwx------+ 4 csteele staff 136 Oct 1 10:41 Documents
drwx------+ 20 csteele staff 680 Oct 2 10:08 Downloads
drwx------@ 59 csteele staff 2006 Sep 20 19:44 Library
drwx------+ 3 csteele staff 102 Sep 20 13:10 Movies
drwx------+ 3 csteele staff 102 Sep 20 13:10 Music
drwx------+ 3 csteele staff 102 Sep 20 13:10 Pictures
drwxr-xr-x+ 5 csteele staff 170 Sep 20 13:10 Public
drwxr-xr-x 6 csteele staff 204 Sep 29 10:53 stuff
ls -la
QUIZ TIME!
Creating Directories
The command "mkdir" ("make directory") followed by the name of the new directory will create a new child directory inside the current directory.
Colt ~
mkdir catpics
catpics
stuff
ls
catpics
cd catpics
pwd
/Users/Colt/stuff/catpics
Creating Files
The command "touch" followed by the filename and file-type extension will create a new file of that type.
Colt ~
touch favs.txt
catpics
stuff
favs.txt
ls
favs.txt
SUPER QUICK ACTIVITY!
- Make a new "animals" directory
- Inside of "animals" create "salamanders" and "frogs" directories
- Inside of "salamanders" add a new file "axolotl.txt"
- Inside of "frogs" add a new file:
PyxicephalusAdspersus.txt (pixieFrog.txt is fine)
axolotls Are awesome
- Really adorable smile
- Once worshipped by Aztecs
- Can regenerate limbs, skin, and spinal cord!
- 1000x more resistant to cancer than any other animal on earth!
- They glow in the dark
PIXIE FROGS
Moving / Renaming Things
Files can be moved or renamed using the "mv" (" move") keyword, which takes two arguments: the source and the destination.
Colt ~
mv favs.txt GOAT.txt
catpics
stuff
favs.txt
GOAT.txt
ls
GOAT.txt
mv GOAT.txt ../
ls
cd ..
ls
GOAT.txt catpics
Removing Files
Files can be deleted using the "rm" ("remove") keyword.
Colt ~
ls
catpics
stuff
GOAT.txt
GOAT.txt catpics
rm GOAT.txt
ls
catpics
Removing Directories
Directories can also be deleted using the "rm" keyword, with the added option "-r" ("recursive"). You can also use "-f" ("force") to prevent warnings.
Colt ~
ls
catpics
stuff
catpics
rm -rf catpics
ls
Warning: "rm -rf" is a dangerous command! Be extremely careful what folder you pass to it because you will never get it back.
QUIZ TIME!
Recap
- OS file structure is hierarchical, tree-based
-
Navigate using these commands:
- cd "change directory"
- pwd "print working directory"
- ls "list contents"
-
Remember these aliases:
- / is root directory
- ~ is home
- . is current
- .. is parent
-
Manipulate files with:
- "mkdir" create directories
- "touch" create files
- "mv" move and rename
- "rm" to remove files, "-r" to remove directories
YOUR TURN
Git
and
github
Objectives
- Learn the difference between Git and GitHub
- Download & Install Git
- Learn how to stage, commit, and push files to GitHub
Git
Git is the most popular "version control system" - a tool to keep track of file changes over time.
It allows you connect your code to online repositories to back up everything easily.
It also makes collaborating with other people on code projects more manageable through branches.
GitHub
GitHub is an online service that hosts git repositories for developers.
It's also a major platform for collaboration on both private enterprise and open source projects
GitHub repositories keep track of entire code history online, so you get both the current state of files and also all previous versions.
Git Workflow
1a. Initialize a local repository on your computer
2. Change (create, edit, move, remove) files on your computer
3. Stage the files to be committed
4. Commit the files to a new version
5. Push changes to the online repository
1b. Clone (download) an online repository onto your computer
or
Initializing a Git Repository
Once git is installed, any directory on your computer can be turned into a repository by typing "git init" inside the folder.
This command creates a "hidden" .git folder in the directory which is where your versions are stored.
Initialized empty Git repository in /Users/Colt/test/.git
Staging Files
One you have created some files in your repository, you can add them to the stage by typing "git add" followed by the filename or parent directory of the files to add all of them.
monty.py
git add .
monty.py
Stage
Changes in local git repository
Staging a file takes a snapshot of it at a point in time, which will prepare it for a new commit (the next version of the repo).
Committing
Use the command "git commit" to save a new version of the repository. Use the "-m" (message) argument followed by a short description to explain the new version.
monty.py
Stage
git commit -m "added monty python"
.git directory
The new commit stores the snapshot in the .git folder. Every commit gets indexed with an auto-generated unique hash so git can find it easily later.
a84c25deac4a8b7c899c34694b569d88349d5a8b "added monty python"
A bit about Remotes
So far, all of the changes we're making are affecting our local .git folder only. Our changes are thus only on our machine.
We can add a remote origin by making a GitHub repository and typing the command "git remote add origin" like so:
git remote add origin https://github.com/<your_github_handle>/<your_repo_name>.git
Pushing
After you've set up a remote origin, use the command "git push" to publish your changes to your online GitHub repository.
local .git directory
Pushing synchronizes the local and remote repositories. Sometimes you will have to "git pull" first to bring your local repo up-to-date before pushing.
a84c25deac4a8b7c899c34694b569d88349d5a8b "added monty python"
Repository on GitHub
a84c25deac4a8b7c899c34694b569d88349d5a8b "added monty python"
git push origin master
Recap
1a. Initialize a local repository on your computer
2. Change (create, edit, move, remove) files on your computer
3. Stage the files to be committed
4. Commit the files to a new version
5. Push changes to the online repository
1b. Clone (download) an online repository onto your computer
or
git init
git clone https://github.com/<your_github_handle>/<your_repo>.git
echo "just putting text in this file" >> README.md
git add .
git commit -m "my first commit"
git push origin master
YOUR TURN
The Command Line(MAC)
By colt
The Command Line(MAC)
- 13,352