Bash commands

Question 1

List contents of the directory

1) Display long form
2) Print one entry per line
3) Recursively list subfiles
4) Show hidden (dot) files

Answer 1

ls

1) ls -l
2) ls -1
3) ls -R
4) ls -a

Question 2

Prints text to the cmd window

printf

Answer 2

echo

Improved echo that allows for formatting

Question 3

Creates a file

Answer 3

touch

Update the access and modification times of each FILE to the current time

A FILE argument that does not exist is created empty, unless -c or -h is supplied

Question 4

Create a directory

Create a directory with a subdir path

Answer 4

mkdir
Specify multiple directories
mkdir -p

Question 5

Find out what a command does by printing manual or get help for a command

Answer 5

man

Question 6

Print working directory

Answer 6

pwd

Question 7

Change directory

1) One level up
2) Current Dir
3) Home Dir

Answer 7

cd

1) cd ..
2) cd .
3) cd ~

Question 8

Move or rename a directory

Answer 8

mv

If filepath is the same, renames the file name

Question 9

Remove empty directories

Answer 9

rmdir

Specify multiple directories

Question 10

Locate a specific file or directory

Answer 10

locate

You can keep your search broad if you don’t know what exactly it is you’re looking for, or you can narrow the scope by using wildcards or regular expressions.

Question 11

View the contents of a text file - displayed one page at a time

1) Go down
2) Quit
3) Go to the next file

Answer 11

less

Specify multiple filenames

1) spacebar to scroll down
2) :q
3) :n

Question 12

Takes the output of a command and saves it to a file

Answer 12

Using the redirect operator >
echo Test > test.txt
head -n 5 filename.csv > head.txt

Question 13

1) Read a file in CLI
2) Display contents with line numbers create a file, and concatenate files
3) Concatenate the outputs of two files and redirect it to a new file
4) Create a new file using the cat command

Answer 13

cat

cat -n

cat file1.txt file2.txt > combinedfile.txt

cat > file_name.txt
* type text, ENTER, ctrl + D to save the file

Question 14

1) Print a list of commands run recently
2) Rerun a command based on its history number
3) Clear history

Answer 14

history

!600

history -c

Question 15

1) Show lines containing specific values
2) Show lines that don’t match - invert the match
3) Print line numbers for matching lines
4) Print count of matching lines

Answer 15

grep

grep -v

grep -n

grep -c

Question 16

Count the records in a file – lines

Count the records in a file – characters

Count the records in a file – words

Count records that match a term using pipe

Answer 16

wc -l

wc -c

wc -w

grep | wc -l

Question 17

Specify many files using a wildcard operator

Answer 17

folder/*

head -n 3 *.txt
Prints the first 3 lines of all .txt files

Question 18

Pipe | operator

Answer 18

Takes the output of a function and passes it as the input to another

Question 19

1) Reads the start of the file
2) Reads the end of a file
3) Specify number of lines to read

Answer 19

head -n 3

tail -n 3

Using the -n option

Question 20

Exit out of a session

Answer 20

exit

Question 21

Clear your terminal window

Answer 21

clear

Question 22

View current processes running in bash

Answer 22

ps

Question 23

Copy files / directories

Answer 23

cp old_name new_name

Question 24

Add a temporary alias

Remove an alias

Answer 24

alias c=”clear”

General syntax: alias =”command_name”

unalias

Question 25

Open up the nano text editor

1) Write out to a file name
2) Exit nano editor

Answer 25

nano

1) ^O
2) ^X

Question 26

Kill the current (foreground) process

Answer 26

^c

Question 27

Remove an entire directory

Answer 27

rm -rf

Recursive and force

Question 28

Search a previously executed command in the command history

Answer 28

^r then enter search terms

Question 29

View all environment variables

Answer 29

printenv

Question 30

Execute a shell script

Answer 30

./script_name.sh