Introduction to Bash!

Learning Bash Terms and Basic Commands

Terms to learn

Command : A String the user inputs into the shell that runs a program

Directory (dir) : A file that contains refences to other files. You can pretty much call this a folder

Current Working dir : The dir that you are currently working in

Home Dir : An enviorment variable ( We will talk about enviormental var later) that represents a user base dir

Root Dir : A dir of the highest level

Commands learned in this lesson

pwd - prints the working directory. Tells you where are you at in the shell 

whoami - tells you what user you are

ls - list the contents of the directory 

cd <directory> - change directory 

touch <filename> - creates a new file

mkdir <directoryname> - created a new dir

cat <filename> - displays the contents of a file 

First Exercise, getting familiar with bash

First we will go to the online terminal Alice and Bob provided yesterday: TERMINAL

1. Use pwd and note what dir you are in
2. Use whoami to see what user you are
3. Use ls to see what is in that dir
4. NOTE: You should see a combination of dir and files if not don’t worry we can take care of that shortly
5. Use mkdir bash to created a new dir named bash
6. Type ls so you know see you have created a new dir named bash
7. Now we want to change our current working dir to bash try cd bash Note you can replace bash with any dir if you want to go somewhere else
8. User pwd again to see if you are in the bash dir
9. Notice how there is a more dir attached to bash. Something like User/bash this is known as your absolute path. /User is the parent dir of /bash. You might not see ‘User’, but in other bash terminals you will
10. Let’s go back to our parent dir. Try cd .. to change dir to the parent
11. Again use pwd (last time I promise) to verify you are back to the parent
12. Now that you know how to move around lets go back into the bash dir
13. Let’s try making a new file type touch newFile to make a file called newFile
14. Use ls to see if the new files were created

Amazing! You have now learned how to create directories and files within a bash terminal!

Navigate the terminal to find flags!

Begin by entering the following commands in the home directory of the terminal…

1. git clone https://github.com/alexarnell/Bash_Tutorial.git
2. Next go into the ‘Bash_Tutorial’ directory to start hunting for flags

Once you find a flag, input it in the answer box on Learnification.fun under the module Week of Cyber Day 2! Good Luck!

Total Number of Flags: 5

One More Flag!

Now that you can get around your shell we are going to teach you how to use some tools in your shell. In this lesson we what to create a directory and learn how to search files

Commands learned in this lesson

echo <string>  - displays a line of text/string that is passed as an argument 

rm <filename>  -  removes files

rm -R <directory name>  -  removes directories

grep <string> <filename> - searches a file for a particular string, 
and displays all lines that contain that string

pid - prints the process ID of the shell

kill <pid> - kills a running process

clear - clears the terminal screen of text

Steps

1. Use pwd and note what dir you are in
2. Use echo with a string as an argument to see how the command works
3. Use mkdir to create a directory named “Trash”
4. After creating the Trash directory, since it is infact trash, use rm -R to remove the directory
5. NOTE: Once you remove a file or directory, it is near impossible to get it back, so be careful!
6. Find the file named “names.txt” and use the cat command to see the contents of the text file
7. Alot of names right? now since the file is taking up a large amount of our screen space, use clear so the names are removed from the screen.
8. Now there is a Flag hidden within “names.txt” yet instead of going through the 20,000 lines of code that the file contains, use grep to try and find the Flag!

Put the Flag in theanswer box on Learnification.fun under the module Week of Cyber Day 2

You Have Completed the Bash Lessons!

You can now consider yourself a bash specialist. Take this badge and put it on your website. If you use your skills, you can inspect the page and find the URL used to generate this image!