UNIX / Linux Basics

Question 1

What are priced packages of software built on top of Linux called

Answer 1

Distributions, like Ubuntu

Question 2

What is free software

Answer 2

Software that can be USED at no cost (but not necessarily acquiring a copy by purchasing)

Question 3

When did UNIX become developed and when did it become available and where

Answer 3

early-70s, 1970; mid-70s, 1975, initially at universities

Question 4

What is BSD

Answer 4

Berkeley Software Distribution (University of California)

Question 5

When was Linux created

Answer 5

Early 90s, 1991

Question 6

What is the official computer environment standards and when were they published

Answer 6

POSIX (Portable Operating System Interface for Computer Environments), is a section of IEEE that defines the API (Application Programming Interface), the shell, and the OS utility interface, and was written in the late1980s (1988)

Question 7

Linux is not good for peripherals

Answer 7

False - Linux support is often first to support peripherals or interface cards. This is however not the case for graphics cards and the like as those companies do not release specs nor source code often or ever.

Question 8

What are binaries

Answer 8

Files that are compiled into a pattern that the kernel would recognize as an executable (as opposed to source code or user data), making it so that the kernel would begin following those instructions when running its open-file procedure and identifying this (running a program). They are called binaries because the files are “compiled” into machine instructions for the kernel to follow bit-by-bit, achieved by removing all of the “text” that was only there for humans to read and converting the file contents to bitwise instructions.

Question 9

What is a hypervisor

Answer 9

A Virtual Machine Monitor (VMM)

Question 10

What is the software that manages virtual machines called

Answer 10

VMMs (Virtual Machine Monitors) or Hypervisors

Question 11

What are the 9 advantages of VMs

Answer 11

1. Isolation Safety
2. Isolation Security
3. Maximize Usage / Minimize Power Consumption
4. Develop Portability
5. Test Anything
6. Server Variety
7. Simulate Networks
8. Sandbox Freedom
9. Quick-Boot Snapshots

Question 12

What type of OS is Linux

Answer 12

GENERIC because it is not written for specific hardware (not proprietary)

Question 13

Why is Linux portable and what does portable mean

Answer 13

Portable software means it can run on different machines that have different hardware. Linux is portable because it is written in C, which is a machine-independent language.

Question 14

Is UNIX portable

Answer 14

Not initially, because it was written in assembly language, which is machine-dependent

Question 15

Why is C powerful

Answer 15

It gives the ability to write machine-independent programs to promote portability

Question 16

What is the difference between a job and a process

Answer 16

Jobs have processes, but processes don’t necessarily come from jobs.
Jobs are higher-level, processes are lower-level.

Question 17

What is FHS

Answer 17

Linux’s Filesystem Hierarchy Standard

Question 18

What is a shortcut called in Linux

Answer 18

A Link

Question 19

What is a shell

Answer 19

A command-line interpreter that acts as an interface between the user and the OS by reading the user input and executing them as commands

Question 20

What are the 4 most popular shells

Answer 20

1. Bourne Again Shell (BASH)
2. Debian Almquist Shell (DASH)
3. TC Shell (TCSH)
4. Z Shell (ZSH)

Question 21

What is a file that is a series of shell commands called

Answer 21

For Linux they are called shell scripts
For Windows they are called batch files

Question 22

What is the functionality called that uses * to find filename matches

Answer 22

Ambiguous file references

Question 23

What is the characteristic of Linux’s I/O regarding devices

Answer 23

Linux I/O is “device independent”, meaning that input or output can be pulled from or sent to any device due to devices being interpreted as files along with Linux’s high-level redirection functionality

Question 24

Are shells interpreters

Answer 24

Yes, because they do not compile programs (the files being ran are not converted into binaries)

Question 25

What does BASH do to fix the slowness of interpreters

Answer 25

It can compile functions into memory

Question 26

What is a kernel

Answer 26

Also called an OS, controls the hardware of a computer and provides an environment that programs can run on

Question 27

What are the commands to the kernel called and what are the 3 layers that can execute them

Answer 27

System calls. Shells, library routines, and applications

Question 28

What are library routines

Answer 28

Collections of system call functions

Question 29

What is the terminal window called

Answer 29

Command-Line Interface (CLI), a “textual interface”

Question 30

What is the file that contains the text you see BEFORE you log in

Answer 30

/etc/issue

Question 31

What is the file that contains the text you see AFTER you log in

Answer 31

/etc/motd

Question 32

When logging in as x@y, what is x and what is y?

Answer 32

x is the username, y is the system

Question 33

Why is it a good idea to exclude a GUI for a server

Answer 33

GUIs add more tasks, so its wasteful and makes the system more vulnerable

Question 34

What is pretty print called

Answer 34

Pseudographical Interfaces

Question 35

What is the most dangerous way to stop a program or job, how do you do it, and why

Answer 35

Using the KILL command as follows (if the job number is 3):
kill -KILL %3
This is dangerous because it ALWAYS stops the program no matter what, and does not allow the program to run any procedures that it typically would run when the program is signaled to stop, leading to corruption

Question 36

What order of commands should you do when trying to stop a program

Answer 36

1. Suspend
2. Quit
3. Kill

Question 37

What username is the “super duper admin”

Answer 37

root

Question 38

What is sudo

Answer 38

A way for you to use root privileges, like su, but you specifically use your own password

Question 39

How do you get help

Answer 39

Use the “man man” command, or specify the utility replacing the 2nd man

Question 40

What is a reason most people forget of not being able to log in

Answer 40

The filesystem is full!

Question 41

What are technically the only 2 chars that cannot be on a filename

Answer 41

\ and [NULL]

Question 42

Where is your home directory defined

Answer 42

/etc/password

Question 43

What is it called when you use \ to use a special char as its literal char

Answer 43

Quoting or escaping

Question 44

When you give Linux a command, how does the shell know what it means

Answer 44

It searches the $PATH list of directories that contain programs where the command given might exist as one

Question 45

What state is the shell in while the process of a command is being executed

Answer 45

sleep

Question 46

What does the shell do with command arguments and what happens if its wrong

Answer 46

The shell only passes them to the utility program, and what happens is up to the code in the program. Sometimes bad arguments are completely ignored and the program runs anyways.

Question 47

How big is a block

Answer 47

512 bytes