Command Line / Shell

Question 1

Terminal (or Terminal Emulator)

Answer 1

A program that accepts text based commands and can render text on the screen

Question 2

Shells

Answer 2

Interpret the commands you type and execute them. Often referred to as “REPL”s:

Read - Read the commands you type

Evaluate - Evaluate those commands, usually by running other programs on your computer

Print - Print the output of those commands

Loop - Give you a new prompt to type another command and repeat

Question 3

Command to print something

Answer 3

echo

Question 4

Prefix when you want to use a variable in a terminal command

Answer 4

$

Question 5

Command to see the commands you’ve typed in the past

Answer 5

history

Question 6

Keys to use to quickly cycle through your command history

Answer 6

Up and Down arrows

Question 7

Command to clear terminal screen

Answer 7

clear

OR

ctrl + l

Question 8

Command to see the filepath of your current working directory

Answer 8

pwd

Question 9

Command to see the contents of your current working directory or a downstream directory

Answer 9

ls

ls filepath

Question 10

Command to see the contents of your current working directory (including hidden files)

Answer 10

ls -a

Question 11

Command to move into (or down) a directory/filepath

Answer 11

cd filepath

Question 12

Command to move back (or up) directories

Answer 12

cd .. (one directory)
cd ../.. (two directories and so on)

Question 13

Command to move to home directory

Answer 13

cd ~

Question 14

Absolute vs Relative Path

Answer 14

Absolute - Filepath that starts at the root of the filesystem

Relative - Filepath that takes into account your current directory

Question 15

Command to view the contents of a file or files combined

Answer 15

cat filename (single file)

cat filename1 filename2 (multiple files)

Question 16

Command prints the first or last n lines of a file (5 lines in this example)

Answer 16

head/tail -n 5 filename

Question 17

Command to view the contents of a file one page (or line) at a time

Answer 17

less filename

less -N filename (w/ line numbers)

Use spacebar to scroll down a page and “b” to scroll back up

Question 18

Key to press to exit out of the currently running process

Answer 18

“q”

Question 19

Command to create a new directory inside a current directory

Answer 19

mkdir directory_name

Question 20

Command to change filename

Answer 20

mv filename new_filename

Question 21

Command to move file

Answer 21

mv source_filepath destination_filepath

Question 22

Command to delete a file or empty directory

Answer 22

rm filename
rm -r directory_name

Question 23

Command to copy a file or directory from one location to another

Answer 23

cp filename destination_filepath/

cp -R current_directory new_directory

Question 24

Command to search for text in files

Answer 24

grep “example” filename (single file)

grep “example” filename1 filename2 (multiple files and so on)

Question 25

Command to search for text in current directory and all subdirectories

Answer 25

grep -r “example” .

Question 26

Command to find files and directories by name

Answer 26

find directory_path -name filename

” * “ character is a wildcard that matches anything, if you’re trying to find filenames that contain a specific word

Question 27

Command to see which user is logged in

Answer 27

whoami

Question 28

Command to print out the permissions of each file and directory in long format

Answer 28

ls -l

Question 29

How are permissions of an individual file or directory visually represented?

Answer 29

10 character string

-: Regular file -rwxrwxrwx
d: Directory drwxrwxrwx

First 3 characters are owner permissions
Middle 3 characters are group
Last 3 characters are public

Question 30

Command to change the permissions of a file or directory

Answer 30

chmod

chmod -R u=rwx,g=rwx,o=rwx DIRECTORY/FILENAME

Question 31

Shell Scripts

Answer 31

Text files that contain shell commands

End with .sh

Question 32

Command to change the owner of a file or directory and it requires root privileges

Answer 32

sudo chown -R root filename/directory