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Learn the Command Line!
AR199 (74)

How to use Bash

Hi, today I will be teaching you how to navigate the file system using a software called Bash. Bash stands for Bourne Again SHell. Bash is the most popular Terminal software. Terminal is an application that comes installed on Windows, Mac, and Linux, which you can use to navigate between, create, and view files.

Note: If you see something called CLI, just know that is shorthand for "Command Line"

Opening Bash on MacOSX

Bash is the default Terminal Program in MacOSX.
Bash comes installed on all versions of MacOS before MacOS Catalina. MacOS Catalina and after, there is a very similar application called Zsh. It's basically the same thing. To open Bash, first navigate to Finder. Then, go to the Applications folder. In there, look for Terminal. Double click the icon, and voila! You have opened Bash on MacOSX!

If you had a little trouble understanding all this, here's the step-by-step version

  • Navigate to Finder.
  • Go to the Applications folder.
  • Search for Terminal.
  • Double click the icon that shows up.

Opening Bash on Linux and Ubuntu

Bash is the default Terminal program in Linux and Ubuntu.
To open Bash in Linux or Ubuntu, go to the list of programs and open the program that says Terminal or Terminal Emulator. Open it, and you have opened Bash on Linux/Ubuntu!

Opening Downloading Bash on Windows

Opening Bash is much more complicated on Windows. Sadly, Windows does not use the Bash software for Terminal/Powershell/Command Prompt. While the Bash and the software Windows uses for its CLI are different, some commands that are available in Bash are not in Windows' CLI. So just take note that Bash is much better. Since Bash is not directly available on Windows, we will be downloading something called Git Bash. This is virtually the same thing as Bash.

Okay, so now let's actually download Git Bash for Windows.

First, navigate to this site: Git Bash.
Then click the Download link. If you can't see it, here is the link: Download Git Bash. You may need Administrator control over the computer. Go through all the steps the Wizard takes you through. At some point, it may ask you for your text editor preference. I recommend selecting Visual Studio Code. Finally, press Finish. The application might start up automatically, or, if it doesn't, go to the Windows search bar. Search for Git Bash. Press Enter. You have successfully opened Bash for Windows!

Do not ever 'Pin' Git Bash to your taskbar in Windows. Some glitches may occur while doing this.

That was quite a lot! If you had trouble understanding the steps, here is the task-by-task version

  • Open the Git for Windows link: Git Bash
  • Click the download link: Download Git Bash
  • You might need Administrator control over the computer to download Git Bash. Do what the download wizard says. When it asks you for the text editor of your choice, I recommend you select Visual Studio Code.

Now let's actually start using Bash!

First, we're going to learn some very basic words. Directory means a folder. Files are things that contain information like words or code.
Before we start learning the commands, I just need to tell you a few very useful tricks:
1. Using the tab key. This can be very useful when typing out long directories or files. If you want to navigate to a directory called "Something Random", you can use this: cd "Something + 'tab'". When you hit the tab key, it will automatically fill up the directory name. It's okay if you don't understand what cd means. You will learn it before the end of this tutorial.
2. Another very useful trick is clear. This just cleans up the Terminal.
Next I'll teach you some commands.

First is cd.

cd stands for Change Directory

cd changes from the current directory to the specified directory. For example, say my current place is /c/users/username/. The next directories I can go to are Desktop, Downloads, Documents, and some more. I'll teach you how to see that these directories are accessible later. I want to go to the Desktop directory. So, I type in cd Desktop. And voila! You are now in the Desktop directory! However, IF the next directory is two or more words, you must use quotes around the directory you want to go to. For example, let's go back to my C:\Users\username directory. Say there is another directory called My Documents along with the Desktop, Downloads, and Documents. Then, to change from the username directory to the My Documents directory, you would do cd 'My Documents'. You can use single quotes or double quotes. Next, going off of the cd command is the cd .. command. The cd .. command goes up one current directory. Remember when I was at /c/users/username/desktop/? I went back to /c/users/username and navigated to /c/users/username/'My Documents'. To do that, I could do cd ../'My Documents'.

What does this do?
  1. cd .. goes up one directory. (From /c/users/username/Desktop/ to /c/users/username/)
  2. /'My Documents' is a continuation of the cd command. It goes to the My Documents directory.

Second is ls.

This is ls as in the lowercase L, not the number one
ls means LiSt

ls basically lists all the directories and files accessible in the current directory. Remember, earlier, how I knew that the directories available in the username directory were Desktop, Downloads, Documents, My Documents, and some other stuff? Well, I figured that out using ls. This can be really helpful when you don't have all the directories and files that are in a directory memorized. There are some other things you can add on to ls such as ls -l, ls -a, and ls -t. But for the sake of simplicity, I'm not going to go into detail about these commands.

Third is pwd

pwd means Print Working Directory

pwd is a really simple command. All it does is show the current working directory. For example, if I don't know what directory I am on right now, I can simply use pwd to find that out.

Fourth is mkdir

mkdir means MaKe a new DIRectory

Now is when you really start harnessing the power of the CLI!
mkdir is an awesome command that makes a new directory!
For example, let's say that I am in the root directory right now. The root directory is the base directory I see when I start up Terminal or Bash. For me, it is /c/users/username/. On MacOSX it is a little different, but don't worry. Say I want to make a new directory called tutorials where I store all my tutorials in HTML format. I do the following command: mkdir "Tutorials". Now, to see if I succeeded in creating that new directory, I can do: cd "Tutorials". Yay, you just created a new directory!

Fifth is rmdir.

rmdir means ReMove DIRectory

rmdir removes the specified directory. Remember the directory Tutorials we created a while ago? Well, we just realized we don't want this to be in the root directory. We want it to be in our Desktop. So, let's harness the power of rmdir and do this!
1. If you are still in the Tutorials directory, go up one directory
2. Remove the Tutorials directory. Check the hint below if you don't fully understand how to do this.
3. Go to the Desktop directory.

  • In step 1, do: cd ..
  • Hint: For step two, do the following command: rmdir "Tutorials"
  • In step 2, do: cd 'Desktop'
  • Make a new directory called "Tutorials" in Desktop.

    Note: rm -r can also be used instead of rmdir.

Sixth is touch

touch creates a new file

touch creates a new file. To see this in action, first navigate to your Tutorials directory in Terminal. It should be in Desktop. Next, do the following command: touch "index.html". Now you have a file! If you do ls, you should be able to see that it lists index.html. I will teach you how to put content in the file in a bit.

Seventh is rm

rm means ReMove

rm removes files.
So we removed directories, but we didn't remove files! We just decided that we don't want the HTML file to be named index. So, we are going to delete the file and make a new file with a different name! Make sure you are in the "Tutorials" directory. You can make sure of this using the pwd command. Do ls to see if the "index.html" file is still there. Now, do the following: rm "index.html". Make sure you get the name of the file exactly right, or else it won't work. Now do ls. You shouldn't see anything. And you just learned how to delete a file in Terminal! Now make a new HTML file called LearningCLI.html. Do ls to make sure the file got created. You should only see LearningCLI.html.

Eighth is echo

echo basically puts words in files.

First navigate to the Tutorials directory. Do ls to make sure "LearningCLI.html"
echo is one of the most handy commands in CLI! To use echo, do the following:echo "I'm learning the CLI!"" >> "LearningCLI.html"
Now use the command cat(which we'll learn about later) to do this: cat "LearningCLI.html"

Ninth is cat

Used the simplest way, cat can show the contents inside a file

This is an on-your-own exercise. Go to Terminal, and navigate to a directory containing some .txt file. Do: cat filename. You should see the contents inside the file!

Tenth is grep

grep searches for the specified file among all the available directories. grep means “global regular expression print.” It searches files for lines that match a pattern and then returns the results. It is also case sensitive.
We do NOT need quotes when searching for a file or directory.

This is very confusing, so I will not go into detail about it. Feel free to Google it.

I have included a handy table that includes all the commands I taught and what they do.

CommandWhat It Does
cd directoryNavigates to the specified directory
cd ..Goes up one directory
lsLists all directories and files accessible in the current directory.
pwdShows the current working directory
mkdir newdirectoryMakes a new directory
rmdir unwanteddirectoryRemoves the specified directory
rm unwantedfileRemoves the specified file
touch file.txtCreates a new file in the current directory
echo wordstoputinfilePuts words in specified file using redirect symbol: >>
cat fileShows the contents inside a file
grepSearches for the specified lines inside a specified file. Format: grep linetosearch filetosearchin.