Bash Shell (Linux)

Question 1

cd..

Answer 1

Navigates back to parent directory of current directory

Question 2

cd

Answer 2

Change directory
(Is how to navigate to a different directory in current directory)

Question 3

grep

Answer 3

Used to search for a string of text. Consists of 2 arguments. First argument is string of text (if more than 1 word, use quotes to indicate the string). The Second argument is the file being searched

Ex: grep OS updates.txt

Question 4

ls (LS)

Answer 4

Lists names of files and directories in current directory.

Question 5

pwd

Answer 5

Print working directory. Displays current working directory.

Question 6

clear

Bonus- what keys can also be used

Answer 6

Clears terminal

Bonus: CTRL+L

Question 7

/ (Slash)

what is the 1st / in a file path and the difference between that and others after.

Answer 7

The first / indicates the root and each other / indicates the next directory path down the hierarchy.

Question 8

cat

Answer 8

Displays the content of a file.

Question 9

head

Answer 9

Displays the top 10(by default) lines of a file.

Question 10

tail

Answer 10

Displays the last 10(by default) lines of a file.

Question 11

-n X (replace X with any number)

Answer 11

Can be added to cat, head, Or tail to change the default amount of lines of a file that is displayed.

Question 12

less

Bonus: what keys are used in less, and their function?

Answer 12

Displays content of a file one page at a time. BONUS: Spacebar -move forward a page. b -move back a page.
⬆️key -forward one line. ⬇️key -back one line. q -Quit.

Question 13

whoami

Answer 13

Will display current user directory
(Does not move you to directory)

Question 14

(piping)

Answer 14

Send the standard output of one command as the standard input of another command for further processing.

Question 15

find

Answer 15

Searches files and directories that meet certain criteria.

Such as a certain ‘string of text’, a certain file size, or were last modified within a certain time frame.

Question 16

• (dash)

Answer 16

Indicates an option.

Ex: -n (to modify the number of lines displayed)

Other Ex: -mtime, -name.

Question 17

-name

Answer 17

Searches criteria that is case sensitive.

Question 18

-iname

Answer 18

Searches for criteria that is not case sensitive.

Question 19

• (Asterisk)

Answer 19

Are used to represent zero or more unknown characters.

Question 20

-mtime

Answer 20

Can be used to find files last modified by + or - the number of days.

Command syntax Ex:
-mtime +10
-mtime -10

Question 21

-mmin

Answer 21

Used to find files last modified by any number of minutes.

Command syntax Ex:
-mmin +10
-mmin -10

Question 22

/bin

Answer 22

Directory that stores binary files and other executable files.

Question 23

/etc

Answer 23

Directory that stores system
configuration files.

Question 24

/tmp

Answer 24

Directory that stores temporary files.

Question 25

/mnt

Answer 25

“Mount” Directory that stores media such as USB and Hard drives.

Question 26

/home

Answer 26

Home directory for the user. Each user has their own home directory.

Question 27

mkdir

Answer 27

Creates a new directory.

(The mkdir command is followed by what you want the name to be)

Question 28

rmdir

Answer 28

Removes or deletes a directory.
(After, rmdir command is followed by the name of directory you want to remove).

Question 29

touch

Answer 29

Creates a new file.

(touch command is followed by what you want to name the file).

Question 30

rm

Answer 30

Removes or deletes a file.

(rm command is followed by the file name you want to delete).

Question 31

mv

Answer 31

Moves a file or directory to a new location.

(mv command has two arguments after it. The 1st being the file name being moved. The second is the file path the file is being moved to).

Question 32

cp

Answer 32

Copies a file to a new location.

(cp command has two arguments after it. 1st is the file being copied, 2nd is the path the file is being copied to).

Question 33

nano

Answer 33

Is used to edit a file.

(nano, followed by the file name. Will put you into an edit mode that with also show a legend to navigate and edit said file).

Question 34

ls -l (LS -L)

Answer 34

Displays permissions to files and directories.

Question 35

ls -a (LS -A)

Answer 35

Displays hidden files.

Question 36

ls -la (LS -LA)

Answer 36

Displays permissions to files and directories, including hidden files.

Question 37

chmod

Answer 37

Changes permissions on files and directories.
Syntax Ex: chmod g+w, o-r access.txt
permissions returned Ex: -rwxrwxw-x

                                            u        g         o Breakdown:directory/file user group other
                                  d/-   rwx    rwx     rwx

Question 38

sudo

Answer 38

“Super User DO” grants temporary access to root authority.

DO NOT EVER LOG IN AS ROOT! is considered bad practice and can be dangerous.

Question 39

useradd

Answer 39

Adds a new user.

Can add -g to set user in primary group,
Or add -G to set user to secondary group. followed by the user name being added.

              *Need to use sudo

Question 40

usermod

Answer 40

Used to modify existing users.
*uses sudo
Using -g or -G with -a adds user to existing group. Without -a any other groups are removed. Other usermod options include
-d to change the users home directory.
-l (L) to change users log in name.
-L to lock user out of account.

Question 41

userdel

Answer 41

Deletes a user from the system.
*uses sudo

Question 42

chown

Answer 42

Changes ownership of a file, directory or group.
*uses sudo

Ex: sudo chown fgarcia access.txt

Ex: sudo chown fgarcia :security access.txt
(To change group owner, indicated by : )

Question 43

man

Answer 43

“Manual” displays information on other commands and how they work.

Question 44

whatis

Answer 44

Displays a description of a command
in a single line.

Question 45

apropos

Answer 45

Searches the manual’s definitions using a specified ‘string’.

Adding -a will allow another ‘string’.