We’ve been using IDLE to edit code, and that’s fine to get started. But it’s a little bit underpowered for getting to the next level when it comes to programming.
In this section, we’ll look at some tools that professional programmers use to get the job done.
Back in the day, people accessed mainframes through dedicated pieces of hardware called terminals. These looked like old TV sets with keyboards attached. Screens were typically monochrome, either white, green, or amber colored, with pixely text.
Barely anyone has a real terminal anymore, but they have programs called terminal emulators that pretend to be terminals. In fact, real terminals are so rare, and terminal emulators are so common, if you hear someone say “terminal”, they’re certainly talking about a terminal emulator.
So a terminal emulator is a program you run that gives you a text window to interact with your computer.
You know how you point, click, and drag with the mouse to command your computer to do things? We’re going to do the same things, except we’re going type commands in to get them done, instead.
Sometimes you’ll hear people talk about the “shell” and “terminal” interchangeably.
Technically, though, the terminal is what you launch, and then the terminal immediately launches another program, the shell, that you interact with.
The terminal is pretty dumb on its own. All it does it handle input from the keyboard and output to its “screen”. It’s the middleperson between you and the shell. The shell is the real brains of the outfit.
The shell is a program that takes your typed-in commands and executes them, and tells you if something went wrong.
The most popular shell program on Unix-likes and Macs is the Bourne Again Shell (Bash)172, although the Z-shell (Zsh) is growing in popularity. Bash is known by a $ prompt (sometimes prefixed with other information about which directory you’re in, or something similar). Zsh uses a % prompt.
There are multitudes of shells, but we’ll just assuming you’re going to use Bash or Zsh (with a hat-tip to Windows’s built-in shells), and they’re compatible enough for our purposes.
For Windows, there are plenty of options, some of which you have installed already.
Unless you’re going with one of the bash options, you should use PowerShell because it’s newer, better, and maintained.
Almost all of the bash commands we use in this guide also work in PowerShell and CMD.
Hitting the Windows key and running cmd will bring up the CMD prompt. (Type exit to get out.)
Hitting the Windows key and running PowerShell will bring up the PowerShell prompt. (Type exit to get out.)
Git174 is a source code control system. And it’s great. Tons of people use it. You should install it.
When you install it, it installs a bash shell called gitbash that you can use.
The Windows Subsystem for Linux is an awesome piece of kit. It unobtrusively puts a little Linux install on your Windows machine. And then you can use the Linux command line.
To install Follow the WSL setup instructions175
There’s a recommendation in there to also install Windows Terminal, an alternate terminal to the existing ones. It’s a good choice.
After installing, update the system:
sudo apt update
sudo apt -y upgradeand Python should be there; running this should get you the version number:
python3 --versionYou can open a File Explorer window with:
iexplore.exe .(Yes, that’s a period after a space at the end.)
Macs come with a terminal built-in. Run the Terminal app and you’ll be presented with a bash shell prompt.
All Unix-likes come with a variety of terminals and shells. Google for your distribution.
There are a lot of IDEs out there, but a good free one is VS Code.
Visit the Visual Studio Code176 website for downloads.
Let’s get it installed!
When you install:
If you’re using WSL, first run VS Code from outside WSL, and install the “Remote WSL” extension. Then you should be able to run it from inside WSL.
Just install it. No special instructions.
Linux and Unix-like users can use their package manager to install VS Code. Google for ubuntu vscode install, substituting the name of your distro for ubuntu.
If you already have a code editor you prefer using (Vim, Emacs, Sublime, Atom, PyCharm, etc.) feel free to use that, no problem!
In the shell of your choice, if all has gone well, you should be able to type:
codeand have it launch VS Code.
Once launched, click the icon on the left bar of VS Code to manage extensions.
Not all development environments are integrated. Some programmers use standalone editors and debuggers to get the work done.
A typical cycle is:
We’re going to do this old-school. Programmers have been using the command line for over 10,000 years, and it has staying power for a reason.
Launch a terminal and bring up a shell. You can use another shell if you want, but I’ll be talking bash/zsh here.
At the prompt, type the following commands, one per line:
cd
mkdir bgpython
cd bgpython
ls -laThese commands do four amazing things:
cd means change directory. (A directory is the same as a folder.) On a line by itself, it means “change to my home directory”.
mkdir means make directory. We’re creating a new folder called bgpython.
cd bgpython to change into that directory.
ls -la to get a long directory listing (i.e. all the files in that folder.)
At this point you should see something like this:
$ ls -la
total 0
drwxr-xr-x 2 beej staff 64 Nov 18 23:14 .
drwxr-xr-x+ 123 beej staff 3936 Nov 18 23:14 ..This is showing you all the files you have. Namely, there are two of them: . and ... These mean “this directory” and “parent directory”, respectively. (You know how folders can be inside other folders? The outer folder is called the “parent” folder, which is what the parent directory is. If you want to get back to your home directory from here, you can type cd ...)
You should think of the shell as “being” in a certain directory at any particular time. You can
cdinto directories, orcd ..back into the parent, orcdto get to your home directory from anywhere. It’s like the folder you have open that has focus in a GUI.
(The remaining information on each line tells you the permissions on the file, who owns it, how big it is, when it was modified, and so on. We can worry about that later.)
Other than those there are no other files. We’ll soon fix that! Let’s add a Python program and run it!
Usually launching an editor to edit a file is as simple as typing the editor name directly followed by the filename on the command line.
For example, to launch VS Code to edit the file hello.py:
code hello.pyBut wait–isn’t VS Code a full-fledged IDE? Yes, it is. Another popular editor is Vim:
vim hello.pyBut in any case, you’re in the editor and ready to type code.
This is your canvas! This is where the magic happens!
If you get in Vim and have no idea how to get out, hit the
ESCkey and then type:q!and hitRETURN—this will exit without saving. If you want to save and exit, hitESCthen typeZZin caps.Vim is a complex editor that is hard to learn. But after you learn it, I maintain it’s the fastest editor on the planet. I’m using it to type this very sentence right now.
To learn it, I recommend OpenVim’s interactive Vim tutorial and this reference of Vim commands from beginner to expert.
Type the following177 into your editor (the line numbers, below, are for reference only and shouldn’t be typed in):
Pull down File→Save to save the file.
Pop back into your terminal window and type ls -la to get a directory listing:
$ ls -la
total 8
drwxr-xr-x 3 beej staff 96 Nov 18 23:27 .
drwxr-xr-x+ 123 beej staff 3936 Nov 18 23:14 ..
-rw-r--r-- 1 beej staff 87 Nov 18 23:27 hello.pyThere it is! hello.py clocking in at 87 bytes (characters, roughly) in size.
Let’s run this puppy. Remember how the program is just a recipe for doing a thing—what do you think our hello.py program does? Guess!
Then type this to run it (if python doesn’t work, try python3 or py depending on your system):
python hello.pyand hit RETURN! [Angelic Chorus!]
$ python hello.py
Hello, world!
My name's Beej and this is (possibly) my first program!You just wrote some instructions and the computer carried it out!
Next up: write a Quake III clone!
Okay, so maybe there might be a small number of in between things that I skimmed over, but, as Obi-Wan Kenobi once said, “You’ve taken your first step into a larger world.”
Remember to use the four problem-solving steps to solve these problems: understand the problem, devise a plan, carry it out, look back to see what you could have done better.
dijkstra.py that prints out your three favorite Edsger Dijkstra quotes178.