[toc]
ℹ️ NOTE: Check out my Linux Guide (coming soon)
ℹ️ NOTE: ❌ Censored: part of line 5 in the example in the image was removed. It had a directory from a previous job I had.
Most of the time when we use our computers, we do so thorugh a graphical user interface (GUI) (pronounced "goo-ee"). ==A GUI is a system designed with icons and visual representation of the machine's fiel systems.==
Programmers often use another kind of interface called the command line. A command line interface (CLI) (pronounced "see-el-eye"), uses textual commands, rather than dragging and dropping icons, to give the computer instructions.
The applicaton responsible for running a CLI is called a terminal and the program interpreting the commands is called the shell.
ℹ️ NOTE: The terms "command line", "terminal", and "shell" are often used interchageably, at least by the author of this book. I will try to strive to use them more appropriately as much as possible.
Both of the images above represent the same file structure. While the GUI may appearn more user-friendly, as you grow more familiar with the commands available, you'll find there can be advantages to using the terminal.
In the terminal, you'll be able to:
- quickly move through your computer's file structure.
- make new files and directories
- remove items from folders
- install software
- open programs
- run programs directly
🎗️ TODO: Insert instructions for each file system.
The command line is a vital took to learn for any programmer. Over the course of this program and your carreer, you will find yourself navigating to it frequenly.
If you are using a Linux system, you don't really need to do anything. However there are a few things you should probably install based on what distribution you are using. A distribution is basically the flavor of which LInux was interpreted. I'll list three of them in the next paragraph.
Software is installed in packages which are often maintained by a software called a package manager. On Arch Linux and Manjaro Linux distributions, the package manager is called pacman. On Debian, Ubuntu, and Raspbian Linux distributions, the package manager is called apt. On Red Hat and Fedora Linux distributions, the package manager is called dnf. In the older days, Red Hat and Fedora distributions were managed by another program called rpm, but that has since changed.
Fortunately, the folks at Arch Linux provided some what of a "Rosetta Stone" of installation commands which can help interpret what each command is for.
For new users, Ubuntu is a good fit, but for more experienced Linux users, especially those who really want to customize everything, Manjaro is a better choice. Manjaro was created because Arch Linux leaves it up to the users to install everything, which might not be a good idea if you are not familar with Linux. Manjaro is trying to fix that.
Raspbian is a version of Ubuntu (which was based in Debian) intended for use with the Raspberry Pi. Until the Raspberry Pi 4 came around, Raspbian was one of the last few distributions for 32-bit systems because the hardware architecture of Raspberry Pis uses a special set of microprocessors created by a company called ARM.
I recommend giving Raspberry Pi, espeically if you want to learn about things like Secure Shell (ssh) and networking between computers. But all that is beyond the scope of LC101.
Despite what the instructions for this course says, the Mac options isn't as simple as "Good news! The Terminal application comes with every Mac!" More so if it asks questions like "Do you want the terminal to access [insert directory name here]" in some pop-up, which kinds disrups the work flow.
Still you can access the Terminal application in two ways:
- Open a new Finder window and navigate to the Applications folder.
- Open the Applications folder, navigate to the Utilities folder.
- Open the Utilities folder, inside is the Terminal application.
- Add the Terminal to your Dock
- Open the Terminal
- If you prefere to use the LaunchPad program, you can press F4.
- Look in the Other or Utilities folder and look for the Terminal.
- Add the Terminal to your Dock
- Open the Terminal
Windows has moved away from the classic "command prompt" (cmd.exe) to a new program called PowerShell. It sucks. In classic Microsoft motivation, PowerShell is basically Microsoft's attempt to make their own version of a Linux-style command prompt which would include all their terrible ".Net" (dot-net) nonsense to appeal tho the Mac Users who were trying to mimic Linux users.
There are a few options however to make the command line experience so much more bearable:
For almost all the options below, I recommend installing Chocolatey.
Chocolatey is an unofficial package manager for Windows, but it will provide you with some experience using package managers like the ones that Linux uses.
FIrst we will need to install Chocolatey. We recommend you have adminstrative access to Powershell. Type Window Key + X then scroll to Windows Powershell (Adminstrative). You can also type into the search bar Powershell where there should be an option where you can Run as Adminstrator. You may get a security prompt. Click Yes.
YOu will then need to run this command. Select it all!
Set-ExecutionPolicy Bypass -Scope Process -Force; [System.Net.ServicePointManager]::SecurityProtocol = [System.Net.ServicePointManager]::SecurityProtocol -bor 3072; iex ((New-Object System.Net.WebClient).DownloadString('https://chocolatey.org/install.ps1'))This command bypasses the security restrictions. The full story can be found on the Chocolatey install page.
It may take a while for Chocolatey to install, but when it is done, we can install software using the choco command.
If you want to install Node, Git Bash, or VS Code for Windows, I would highly recommend using Chocolatey for that even though it is in the PowerShell.
choco install nodejs-lts
choco install git
choco install github-desktop
choco install vscodeOr install them all at once!
choco install -y nodejs-lts git github-desktop vscodeSeeing as how Powershell wasn't really that appealing, Microsoft gave up and decided to go a new direction that has actually been more appealing but still has many faults: Window Subsystem for Linux (WSL).
In order ot use WSL, ==you need Windows 10==. You can install it using the directions from this page.
There is a downside to this way:
- You are stuck with a handful of common distros, and those distros likely won't be updated. Installed WSL back in 2018, used Ubuntu distro (which is still 18.04) and Microsoft still hasn't provided a new version of this distribution.
- You could be installing the software redundantly. You could find yourself installing a version of a program you installed for Windows installed again for Linux.
- Using WSL to interact with windows on stuff can be problematic. While you can access it through the shell (Your Windows user directory can be access via
/mnt/c/Users/${username}), manipulating files this way can be a problem.
Another option is that you can do is use Git Bash. Git Bash is part of the Windows version of Git. It provides a minimal version of Linux-bash functinaly using a program called MinGW. This version of MinGW is intended for use with an open source C/C++ compiler called GCC.
There is one advantage to using Git Bash. When Microsoft bough Github in 2018 (much to the chagrin of a lot of open source software advocates), it also meant that Microsoft wanted to use some of Git Bash's assest to create Visual Studio Code (VSCode). Github was working on their own independent development environment (IDE) called Atom, which was using Node.js (which mean Node integration) but it was also using Electron (which was kinda clunky at the time).
VSCode users have the option to use Git Bash instead of Powershell as integrated terminal, which is recommended considering now you have the ability to use Git (with Github's extra features) and Node (provided you installed in for Windows).
If you do go this route, I recommend installing VSCode, Git for Windows, and Node using Chocolatey.
While you can access Chocolatey in Git Bash, you CANNOT install or upgrade packages from it. You have to use an ADMINSTRATIVE PowerShell to install software from Chocolatey just as you would need adminstrative access to install software on Windows.
🎗️ TODO: Add instructions for integrating Git Bash with VSCode later.
MSYS2 is another solution. Microsoft doesn't like this one namely because they're not involved.
MSYS2 was actually the main compontent in early program called Cygwin that provided an open source environment for Windows.
We will still need to install it with Chocolatey. However, the advantage here is that when we want to install software with it, we can do as we would if we were using WSL, but use pacman inside of the shell.
ℹ️ NOTE: I have not install this, but I would really like to try it out later.
🎗️ TODO: I should add instructions for using this later.
ℹ️ NOTE: applies to everyone except Windows Powershell and Git Bash.
Some terminal command require the addtion of sudo ad the front fo the command. This name gives the user SuperUser access. sudo is often required when installing software from the terminal.
$ sudo pacman -S nodejs-lts
Password: The terminal will asl you for the machine's password. Press "Enter" when you are finished.
ℹ️ NOTE: When typing, don't be alarmed if you don't see your keystrokes while typing your password. Your machine will still receive this information. Also, you can use backspace if you think you messed up. You'll want to press it a whole bunch of times. But if you get it wrong anyway, you should be allowed a couple more chances to enter it correctly.
If you're attempting to run a command from the terminal and recieve a permission error, check if adding sudo to your command will resolve the error.
A filesystem is a structure for the computer to store files and folders that make up the data of the operating system.
Inside a file system, folders are refered to as directories. Folder that exist inside other folders are called subdirectories. A root directory can refer to a few different things, but essentially means the top most directory of a given system. In other words, a root directory is not a subdirectory, but it will contain its own subdirectories.
Inside the machine you work with call your computer, the root directory is the location of the primary hard drive:
- In Windows, that's your
C:\dirve. - On Mac, Unix, and Linux, that directory is represented as
/.
The root directory is the parent directory for the folders stored inside of it. So you coul say that the subdirectories of a parent directory can also be called the child directories.
Example: Most of you have a
Desktopfolder on your computer (which is actually a subdirectory of your user directory called the home directory). If you created a folder to store you LC101 Homework called"LC101_Homework", then the parent directory ofLC101_HomeworkisDesktop. But you probably shouldn't put that there anyway but use a shortcut to that folder, also called an alias or soft link.
A path for files and folders is the list of parent directories that the computer must go through to find that particular item.
Filesystems have two different types of paths:
- The absolute path is the path to a file from the root directory.
- The relative path is the path to a file from the current directory.
When working with a relative path, you may find yourself wanting to go up into a parent directory to find a file in a different child drectory. in order to do so, you can use .. (two dots) in the file path to tell the compute to go up to the parent directory.
Example: If
homework.jsis a file inside theLC101_Homeworkdirectory, the absolute path to it is/Users/${username}/Desktop/LC101_Homework. (Windows users may find it atC:\Users\${username}\Desktop\LC101_Homework.) If the current directory isDesktop, then the relative path to homework is/LC101_Homework(\LC101_Homeworkfor Windows).If
homework.jsis in a different directory in theDesktopdirectory calledCoderGirl_Homework, and your current directory (also called a current working directory) isLC101_Homework, the relative path to theCoderGirl_Homeworkdirectory would be../CoderGirl_Homework(or..\CoderGirl_Homeworkon Windows).
ℹ️ NOTE: On windows, at least in
cmd.exestill, yo have to use the back slash to to traverse directories. Powershell allows using forward slash like every other operating system.
May programmer use paths to navigate through the file system in the terminal. We'll discuss the commands to do this in the next section.
Moving from a GUI to a CLI can be difficult for people who are used to dragging files from one folder to another. One of the difficulties is simply figuring out whe we are in the file system. Here are some indicators that the terminal gives us to show us where we are:
Jason@Lapis MINGW64 ~
$These lines (which are often one line) is calle the prompt. The prompt lets us know that the terinal is ready to accept commands. Lapis is the name of my computer, my username on this computer is Jason. The tilde (~) tells us we are are currently in the home diretory. The home directory is a folder that contains everything in the computer that belongs to a user.
The home directory varies from operating system:
- On Linux the home directory is generally located at
/home/${username}. - On Mac (which uses Unix), the home diretory is generally located at
/Users/${username}. - On Windows, the home directory is generally located at
C:\Users\${username}.
For each of those items in the above list, ${username} represents the name of a user.
On some operating systems, you can actually customize the appearance of the prompt. One site that can help with that is Bashrc Generator.
There are many command use can sue in the terinal to move through the filesystem of your computer and projects.
| Command | What it does | Notes |
|---|---|---|
whoami |
Tells you who you are, what your username is. | In powershell, it may return the machine name too. |
pwd |
Print Working Directory, where are you in the system. | |
ls [<options>] [<path>] |
List files. Show what files are in a directory. | ls is a fundamental command.There are a list of <options> I could list here, but there's not enough room on this table to describe them all.The <path> is optional. If you don't use it, it will print the files in the current directory |
cat <file> |
Print what's in a file. | cat is actually short for concatentation. cat can be use to concatenate two files together, but it can also be used to print what's in a text file.There's also a command called highlight which is not part of the operating system, but if you can get it (which it should be available through your package manager) I find it to be more helpful tha using cat for look at files. It's still new to me and there are a couple of alias commands in ~/.bash_alias I want to add later to make it more functional. |
less -eFMXR |
Look at something on teh screen but with better control. | less is a program that allows you.These extra options, -eFMXR, are some general options that I use for better control. Using less with another command can allow you to scroll through a file or directory instead of the prompt just dumping it all on you and miss out on something important.Generally less is piped.`cat really_long_file.text |
cd <path> |
Change directory (which is what cd means for short) to the <path> directory. Change your location. |
ℹ️ Note: If you get lost, remember to use pwd to show where you are. |
mkdir [-p] <new_folder> |
Make Directory. Create a new directory. | If you use the -p option, you can create a child directory is inside of a parent directory in one command. mkdir -p parent/child |
touch <new_file> |
Create a blank file | |
rm [-rf] <old_files>... |
Remove (delete) one or more files. | rm -rf /! you will delete your entire system that way! Also bad is rm -rf ~.Be very careful when using -r and -f to delete entire directories of files! There is no Trash/Recycling Bin to recover file from. |
rmdir <old_folders>... |
Remove old folders. | ℹ️ NOTE: You can only delete empty directories with this command. |
man <command> |
Manual. Learn more about a command. | ℹ️ NOTE: The man command is only available on Linux and Mac UNIX. It is not available on Windows or Git Bash. You can try using --help to see if a program has a help feature. |
cp <orignal> <copy> |
Copy a file. | ℹ️ NOTE: You can copy an entire directory. But if if you are copying files, it's just best to copy them one at a time. |
mv <old> <new> |
Move or Rename a file or directory. | This one can be a little tricky. 🎗️ TODO: Maybe provide some context for this one. |
ln -s <source> [<target>] |
Create a soft link (an alias/shortcut) to a file | The -s option is maniditory.The <source> is the file you want to create a shortcut to.The <target> is optional. It provides a different anme for the shorcut we want to create in the directory. A path may prepend the <target> to say where to put it, but the easiest way to use soft links is to use them in the current working directory. |
date |
Print the current time and date. | There are options to manipulate how it appears, but I won't get into that right now. |
nano, vim, nvim (NeoVim) or emacs |
Various text editors. | nano is generally good if you want to quickly edit something.vim is more complex. Everyone freaks out about how to exit from it. Type :q!.Neovim ( nvim) is like vim but with a lot of the things vim doesn't include. I recommend this for advanced users.emacs is to pineapple on pizza! DON'T EVERY TALK ABOUT PINEAPPLE ON PIZZA! |
tmux |
Termial multiplexer | ℹ️ NOTE: This might not be installed, but if you can: DO IT! tmux can save your sessions if you do something dumb or if you use ssh and get disconnected. Google it. |
clear |
Clear the screen | |
node |
Run some progrm that's probably not important. 😜 | ℹ️ NOTE: node provides a command line interface to try stuff with. |
npm |
Node Pacakge Manager | The package manager for node |
git |
Git | Git is a Software Configuration Management (SCM) software. We'll learn more about it later. |
gh |
Git for Github | This is actually a new command. One I want to include in these notes eventualy |
chmod <mode> <filename> |
Change modes | If you want to make a file executable, you need to change the modes. I could list how it all works, but I'll have to do it later. |
chown <user>[:<group>] <filename> |
Change owner | Change the user ownership of a file. 💡 Tip: I recommend using this to also change the group owner ship. sudo chown some_user:some_group filename |
chgrp <group> <filename> |
Change group | Change the group ownership of a file. |
find |
Find and manipulate files. | 🎗️ TODO: Describe what find really does, as well as its relationship to xargs (or is it some other program?) |
| Shortcut | Where it goes | Notes |
|---|---|---|
~ |
The home directory | This directory may vary based on operating system |
. |
The current (working) directory | |
.. |
The parent working directory | |
/ |
The root directory |
There's a ton of other command I could put here, but won't. Check out my Linux Guide later.
🤓 Personal Experience
The shell that is typically part of Linux is called
bash, however there's new shell calledzsh(pronounced "zee-shell" or if you Canadian "zed-shell") that is new, which is what I'm using in my WSL screenshots like the one at the begining of this chapter.) The theme it uses is something called Powerlevel9k which I think I installed using something called Oh My Zsh. (There's also a newer team called PowerLevel10K, but PL9K is still my theme.)One of the things I really like to do is text processing which is basically one of the things that Node does, but there are other tools I like to use.
bash(man bashis a LOOOOOOONG mess. Try looking at it as HTML.)curl- Use this to download files directly (Hacker-y stuff ensues.) Ideal if you want to quickly download and extract packages. (I should ad commands for that later.)grep- Search for text. Generally, using Regular Expression.awk- a mini-programming language. (This page has a lot of one-liners!)sed- called the "Stream Editor". (Here's some useful one-liners.)jq(This is a new tool. You can manipulate JSON in it. Try it!)There's also some fun things you can do in text:
- Check the weather with
curl wttr.in- Colorize text with
lolcat.- ASCII Word Art with
figlet.- Put stuff in text boxes with
boxes.- Access useful cheat sheets with
curl cheat.sh(Admins: No! This does not help people cheat at tests!)
❓ Question: What line in a CLI indicates tha the terminal is ready?
a. prompt b. command c. shell d. There isn't a line that does that.
❗ Answer: a. The prompt!
❓ Question: What shortcut takes you to the parent directory? a.
.b.~c...❗ Answer: c. Two dots referes to the parent directory. One dot refers to the current directory. And the tilde (
~) refers to the home directory.
Quickly navigating thorugh our files systems is just one benefit of using the terminal for programmers. We can also quickly run our code inside of the terminal to set the outputs.
The commands used to run a program in the terminal vary widely based on type of program you want to run. However, no matter what language you are coding in. the doucmentation will include, in some format, ways to run the program in the terminal.
Let's say there's an error in our program like an infinite loop. How do we get it to stop running so we can get back and fix our code?
In many cases, ==typing CTRL+C into the terminal will stop a process that is currently running.== However, if that doesn't work, the exit command can also stop a currently running process. But CTRL+C (Sometimes denoted ^C) will help you kill it.
- If you haven't done so already, set up your command line environment with instructions I added to these notes.
- Using your terminal, navigate to your Home directory using
cd ~. - Use
lsto view the contents of your Home directory. - Use
cdto move into your Desktop directory. For most, the command to do this iscd Desktop/since theDesktopis most often a child of the Home directory. - In the terminal, use
mkdirto create a folder on the Desktop called'my_first_directory'. Look on your Desktop. Do you see it? - Use
cd my_first_directory/to move inside that directory. pwdto check your location.- There, make a file called
'my_first_file.txt'withtouch my_first_file.txt. - Open the file and write yourself a message!
- Back in the terminal, list the contents of your current directory from the terminal with
ls. - Make a copy of your
'my_first_file.txt'from it's current spot to directly on the Desktop withcp my_first_file.txt ../my_first_copy.txt. - Move back out to your Desktop directory from the terminal with
cd ... - Use ls in the terminal to verify your
'my_first_copy.txt'on your Desktop. Open it up. Is it the same as your first file? - Move your copied file into your
'my_first_directory'withmv my_first_copy.txt my_first_directory/. - Use
lsto see that the the copied file is no longer on your Desktop. Typecd my_first_directory/, followed bylsto confirm that your copy has been moved into'my_first_directory'. cd ..to get back out to your Desktop.- Type
rm -r my_first_directory/and do a visual check, as well as ls on your terminal, to verify that the directory has been removed.
🏁 Time for something new! HTML!
#LaunchCode