Ch.3 Exploring the System

Question 1

What does the command file do?

Answer 1

Determine file type

Question 2

What does the command less do?

Answer 2

View file contents

Question 3

How do you specify the directory to list?

Answer 3

ls /usr

Question 4

if ls is commanded what does it list?

Answer 4

The contents of the current directory

Question 5

How do you list multiple directories at once?

Answer 5

ls /usr ~ /usr/bin

Question 6

How do you change the list command output to the long format?

Answer 6

ls -l

Question 7

What do commands kind of look like?

Answer 7

Command -options arguments

Question 8

What do most commands use?

Answer 8

options with consist of a single character preceded by a dash. i.e. -l

Question 9

What are GNU Project options called and how do they look?

Answer 9

They are called long options, and they consist of a word preceded by two dashes

Question 10

What option will list all files, even those with names that begin with a period, which are normally not listed (That is, hidden)?

Answer 10

-a, –all

Question 11

What lists everything but the . and ..?

Answer 11

-A, –almost-all

Question 12

Use this option in conjunction with the -l option to see details about the directory rather than its contents

Answer 12

-d, -directory

Question 13

This option will append an indicator character to the end of each listed name.

Answer 13

-F, –classify

Question 14

In long format listings, display file size in human readable format rather than in bytes

Answer 14

-h, –human–readable

Question 15

Display the results in reverse order. Normally, ls displays its results in ascending alphabetical order.

Answer 15

-r, –reverse

Question 16

sort by modification time

Answer 16

-t

Question 17

What seven things are contained in the ls Long Listing Fields?

Answer 17

1. Access rights to the file
2. File’s number of hard links 3. username of the file’s owner 4. name of the group that owns the file 5. size of the file in bytes 6. Date and Time of the file’s last modification 7. Name of the file

Question 18

What does ASCII stand for and what is it?

Answer 18

(AS-KEY) American Standard Code for Information Interchange. It is a simple encoding scheme first used on teletype machines to may keyboard characters to numbers.

Question 19

Why would we want to examine text files

Answer 19

Many of the files that contain system settings are stored in this format, and being able to read them gives us insight about how the system works.

Question 20

How is the less command used?

Answer 20

less filename

i.e. less /etc/passwd

Question 21

less action to scroll back one page

Answer 21

Page Up or b

Question 22

less action to scroll forward one page

Answer 22

Page Down or space

Question 23

less action to scroll up one line

Answer 23

Up arrow

Question 24

less action to scroll down one line

Answer 24

Down arrow

Question 25

less action to move to the end of the text file

Answer 25

G

Question 26

less action to move to the beginning of the text file

Answer 26

1G or g

Question 27

less action to search forward to the next occurrence of characters

Answer 27

/characters

Question 28

less action to search for the next occurrence of the previous search

Answer 28

n

Question 29

less action to display help screen

Answer 29

h

Question 30

less action to quit less

Answer 30

q

Question 31

explain the meaning behind less is more

Answer 31

less is a replacement of more. it falls into the class of programs called “pagers”, programs that allow the easy viewing of long text documents in a page by page manners. More could only page forward.

Question 32

how would you determine the contents of an interesting file?

Answer 32

file filename

i.e. file john.txt

Question 33

What is the copy and paste trick?

Answer 33

If you are using a mouse, you can double click on a filename to copy it and middle click to paste it into commands

Question 34

The Root directory. Where everything begins

Answer 34

/

Question 35

contain.s binaries (programs) that must be present for the system to boot and run

Answer 35

/bin

Question 36

contains the linux kernel, initial RAM disk image (for drivers needed at boot time), and the boot loader.

Answer 36

/boot

Question 37

This is a special directory that contains device nodes. “Everything is a file” also applies to devices. Here is where the kernel maintains a list of all the devices it understands.

Answer 37

/dev

Question 38

this directory contains all of the system-wide configuration files. It also contains a collection of shell scripts that start each of the system services at boot time. Everything in this directory should be readable text.

Answer 38

/etc

Question 39

Contains shared library files used by the core system programs.

Answer 39

/lib

Question 40

Each formatted partition or device using a linux file system such as ext4, will have this directory. it is used in the case of a partial recovery from a file system corruption event.

Answer 40

/lost+found

Question 41

On modern linux systems this directory will contain the mount points for removable media such as USB drives, CD-Roms, etc. that are mounted automatically at insertion.

Answer 41

/media

Question 42

This directory is used to install “optional” software. This is mainly used to hold commercial software products that might be installed on the system

Answer 42

/opt

Question 43

This directory is special. It’s not a real file system in the sense of files stored on the hard drive. Rather, it is a virtual file system maintained by the Linux kernel. The “files” it contains are peepholes into the kernel itself. The files are readable and will give us a picture of how the kernel sees the computer

Answer 43

/proc

Question 44

This directory contains “system” binaries. These are programs that perform vital system tasks that are generally reserved for the superuser.

Answer 44

/sbin

Question 45

This directory is intended for the storage of temporary, transient files created by various programs. Some configurations cause this directory to be emptied each time the system is reboooted

Answer 45

/tmp

Question 46

This directory tree is likely the largest one on a linux system. It contains all the programs and support files used by regular users.

Answer 46

/usr

Question 47

This directory contains the executable programs installed by the Linux distribution. It is not uncommon for this directory to hold thousands of programs.

Answer 47

/usr/bin

Question 48

The shared libraries for the programs in /usr/bin

Answer 48

/usr/lib

Question 49

Where programs compiled for source code are normally installed

Answer 49

/usr/local/bin

Question 50

On a newly installed Linux system, this tree exists, but it will be empty until the system administrator puts something in it. This tree is where programs that are not included with the distribution but are intended for system wide use are installed.

Answer 50

/usr/local

Question 51

Contains more system administration programs.

Answer 51

/usr/sbin

Question 52

This tree contains all the shared data used by programs in /usr/bin. This includes things such as default configuration files, icons, screen backgrounds, sound files, etc.

Answer 52

/usr/share

Question 53

Most packages installed on the system will include some kind of documentation. In this tree we will find documentation files organized by package.

Answer 53

/usr/share/doc

Question 54

This contains log files, records of various system activity. These are important and should be monitored from time to time.

Answer 54

/var/log

Question 55

The most useful /var/logs

Answer 55

/var/log/messages and /var/log/syslog

Question 56

With the exception of /tmp and /home, the directories we have looked at so far remain relatively static, that is, their contents don’t change. This directory tree is where data that is likely to change is stored. Various databases, spool files, user mail, etc. are located here

Answer 56

/var