Linux Basics

Question 1

cp

Answer 1

cp: Copy file

Copies file and keeps both copies

Question 2

mkdir

Answer 2

mkdir: Make directory

Creates a new directory

Directories in Linux are the same as folders in Windows

Question 3

vim

Answer 3

Used to edit any text based file in terminal

Question 4

rm

Answer 4

rm: Remove

Deletes a file

Question 5

mv

Answer 5

mv: Move file

Moves a file into another directory or subdirectory

Question 6

rm -r

Answer 6

rm -r: Remove recursively

Delete an entire directory and all of its contents

Question 7

touch

Answer 7

Creates a blank file; can be used to verify write permissions in a directory or to work around error messages showing a file is missing

Question 8

df

Answer 8

df: Disk file system

Displays a full summary of the available and used disk space usage of a file system

Question 9

-h

Answer 9

-h: Human readable

Since this starts with a - this is called a flag or modifier, it cannot be run on it’s own

Shows data sizes in KB/MB/GB, etc. instead of in Bytes

Question 10

head

Answer 10

Shows the first 10 lines of a file

Question 11

tail

Answer 11

Shows the last 10 lines of a file

Question 12

tar

Answer 12

Compresses file; like Zip for Windows

Linux also can use zip/unzip for files

Question 13

wget

Answer 13

wget: Website file get

Download a file from the web

Question 14

top

Answer 14

Task Manager for terminal; same as Task Manager in Windows

Question 15

k (Used within top)

Answer 15

Kill process by PID

Question 16

PID

Answer 16

Process ID used in top

Question 17

q

Answer 17

Quit

Question 18

history

Answer 18

Shows the complete history of all commands ran on a machine

Each command is associated with a number; you can rerun any command by entering ! and the associated # (!23)

Question 19

echo

Answer 19

Add text to the end of a file

Adds any data to the end of the desired file before the&raquo_space;

echo Schedule an interview&raquo_space; Prospective_ASRE_Candidates.txt

Prospective ASRE Candidates
Jane Doe
John Smith
Melodi Mullins Schedule an interview

Question 20

echo

echo Cohesity > Employer.txt

Answer 20

Overwrites the data in a file to be replaced with whatever is typed before the >

In the example on the front, we can assume your Employer.txt file shows World’s Best Mama in the body and it will then be changed to Cohesity

Question 21

sudo

Answer 21

sudo: Superuser do

Make the command run with admin credentials

Question 22

cd

Answer 22

cd: Change directory

There are times that you will need to access different commands in different locations, this allows you to switch between locations and work as needed

Question 23

ssh

Answer 23

Provides a secure encrypted connection between two hosts over an insecure network

You will use this command to connect to a node within a customer’s cluster

ssh 10.178.59.26

Question 24

file

Answer 24

Displays file types

Question 25

cat

Answer 25

Output (display) the contents of a text file

Question 26

vi

Answer 26

Unix based text editor, similar to vim

Question 27

netstat

Answer 27

netstat: Network status

Displays TCP connections, routing tables, and statistics

Question 28

chmod

Answer 28

chmod: Change/modify

Change access permissions of file system objects

Question 29

ls -a

Answer 29

ls: List
- a: Show all

List all including hidden files

Question 30

pwd

Answer 30

pwd: Print working directory

Show (print) current directory name

Question 31

flag

Answer 31

Flags are used to modify a command

cat hugefile.log | tail (tail is the flag)
Displays the last 10 lines of hugefile.log

cat hugefile.log | tail -n 5 (tail, -n, and 5 are each individual flags)
The tail command is modified to only display the last 5 lines of hugefile.log instead of the default 10

Question 32

grep

Answer 32

Search a file for a particular pattern of characters, and displays all lines that contain that pattern

Question 33

terminal

Answer 33

Any UI (User Interface) that allows you to enter commands

Common terminals are Ubuntu, WSL (Windows Subsystem for Linux), Terminal (Mac), RHEL (Redhat Enterprise Linux), MobaX

Question 34

pipe

Answer 34

pipe: | (this looks like a l, but it is the capitalize character on the \ key

This is used to add additional commands to a command

cat error_logs.txt | grep power

cat displays error_logs.txt; since this will be a huge file and we know that we want to search for anything related to power so we add a pipe and tell it so search for the word power using grep

Question 35

tfc

Answer 35

When tfc is used it allows you to connect directly to a customer’s cluster via terminal as well as opens the GUI (web based interface that customer’s use to manage their Cohesity software)

Question 36

tfs

Answer 36

When tfs is used it allows you to connect directly to a customer’s cluster via terminal. It will only connect via terminal and opens nothing else.

Question 37

tfb

Answer 37

When tfb is used it allows you to connect directly to a customer’s cluster via the GUI (web based interface that customer’s use to manage their Cohesity software), it will not connect via terminal

Question 38

bang

Answer 38

bang: !

Question 39

hostips

Answer 39

Lists all IP addresses within a cluster; the last one shown is the node you are connected to

Question 40

Node

Answer 40

An individual component within a cluster, each node has it’s own IP address. There can be almost unlimited nodes within a cluster (the most I’ve run across is 80 within a cluster).

Question 41

Cluster

Answer 41

A computer cluster is a set of computers that work together so that they can be viewed as a single system. Unlike grid computers, computer clusters have each node set to perform the same task, controlled and scheduled by software.