Debian Commands

Question 1

Where can you view a list of user groups

Answer 1

/etc/group

Question 2

How do you add a user to an admin group

Answer 2

sudo usermod -aG [GROUP] [USER]

-a (append) is critical or will remove from other groups rather than just adding to a new

Question 3

Find the current date

Answer 3

date

Question 4

Find the current working directory

Answer 4

pwd

Question 5

Current computer name

Answer 5

hostname

Question 6

View directory contents Inc hidden files

Answer 6

ls -a

Question 7

How do you sort results in reverse

Answer 7

sort -r

Question 8

How do you output to a text file

(In to home directory for this example)

Answer 8

> ~/output.txt

Question 9

How to output any potential errors only

(eg of command/script for error logging)

Answer 9

2> [path]

Question 10

How you output to both screen and file

Answer 10

tee [output path]

Question 11

Output and add to existing file

Answer 11

> > [path]

Question 12

Refer to entire contents of current directory

Answer 12

./*

Question 13

File permissions order

Answer 13

User, Group, Others

Question 14

How do you find a binary’s location, manual and source

Answer 14

whereis [binary]

Question 15

How do you find a binary in the PATH variable

Answer 15

which

Question 16

What is the basic syntax for ‘find’

Answer 16

find [dir] [option] [string]

Question 17

How do you view the last 10 lines of a text file

Answer 17

tail [path]

Question 18

How do you view the first 20 lines of a text file.
What is the default number of lines

Answer 18

head -20 <path/file>

Default is 10

Question 19

How do you number lines in a text file

Answer 19

nl [path]

Question 20

How do you search for any/all occurrence of a word and replace it

Answer 20

sed s/word/replacement/g
leave out g for just first instance of word, or replace it with the numerical instance of word.

Question 21

How to request a new IP on WLAN

Answer 21

dhclient [WI-FIDEVICE]

Question 22

How to append a line of text into a file

Answer 22

echo “STRING”&raquo_space; PATH

Question 23

How do you check if a software package is available in the Deb repositories

Answer 23

apt search STRING

Question 24

How to uninstall software Inc config files

Answer 24

sudo apt purge

Question 25

How do you remove software dependencies that are no longer required

Answer 25

sudo apt autoremove STRING

Question 26

How do you install software with Git

Answer 26

git clone [GITHUB URL]

Question 27

What is the change owner command

Answer 27

chown [user] [file]

Question 28

Command to change group of a file

Answer 28

chgrp GROUP FILE

Question 29

How do you change file/dir permissions

Answer 29

chmod <1-7><1-7><1-7> [path]

Question 30

View current default permissions mask

Answer 30

umask

Question 31

How do you SUID bit

Answer 31

Enter a 4 before the regular permissions
Eg chmod 4664 over 664

Question 32

How do you add the SGID bit

Answer 32

Enter a 2 before the regular permissions
Eg chmod 2664 over 664

Question 33

How do you find a command for something when you don’t know what it’s called?

Answer 33

apropos
I.e apropos password

Question 34

How to scp to a remote server

Answer 34

scp [dir] [USER@REMOTESERV]:[dir]

Question 35

common cpio options

Answer 35

-I designates an archive file to use
-i copy in from an archive
-o copy out and create archive
-t create table of contents list
-v verbose
—no-absolute-filenames