03 Exploring The System

Question 1

What command does ‘ls’ invoke?

Answer 1

Lists the contents of the current or specified directory.

Question 2

Describe the output of the command “ls -l”:

Answer 2

Provides the “long listing” (the details) of the current or specified directory.

Question 3

The command ‘ls -l’ was performed and generate the following output. Describe the output:

Total 56
Drwxrwxr-x 2 me wheel 4096 2018-08-07 17:05 myfile.txt

Answer 3

Drwxrwxr-x : File permissions
2: Number of hard links to file
Me: owner
Wheel: owner group
4096: File size
2018…: last modified time
Myfile.txt: file name

Question 4

“Commands are often followed by one or more [blank] that modify their behavior, & further by one or more [blank].

Answer 4

Options / arguments

Question 5

“Commands are often followed by one or more options that modify their behavior, & further by one or more arguments.”

What is meant by ‘arguments’ in the above statement?

Answer 5

‘Arguments’ refers to the items on which the command option(s) act.

Question 6

Describe the options and long options for the following description of the ‘ls’ command.

“Lists all files, even those that begin with a period, which are normally hidden.”

Answer 6

-a / - - all

Question 7

Describe the options and long options for the following description of the ‘ls’ command.

“Output is like ‘-a’, although ‘.’ & ‘..’ are hidden.”

Answer 7

-A / - -almost-all

Question 8

Describe the options and long options for the following description of the ‘ls’ command.

“Normally, if a directory is specified, ls will list the contents of the directory. Supplying this argument will list details about the directory instead.”

Answer 8

-d / - -directory

Question 9

Describe the options and long options for the following description of the ‘ls’ command.

“Append an indicative character to the end of output, for example, a ‘/‘ at the end of directories.”

Answer 9

-F / - -classify

Question 10

Describe the options and long options for the following description of the ‘ls’ command.

“Displays file size in a human-readable format as opposed to bytes.”

Answer 10

-h / - -human-readable

Question 11

Describe the options and long options for the following description of the ‘ls’ command.

“Displays results in long format.”

Answer 11

-l / [no long option]

Question 12

Describe the options and long options for the following description of the ‘ls’ command.

“Displays results in reverse order.”

Answer 12

-r / - -reverse

Question 13

Describe the options and long options for the following description of the ‘ls’ command.

“Sort files by file size.”

Answer 13

-S / [no long options]

Question 14

Describe the options and long options for the following description of the ‘ls’ command.

“Sort output by modification time.”

Answer 14

-t / [no long options]

Question 15

Which command would you use to determine the type of a given file?

Answer 15

file

Question 16

True or False: filenames in Linux are required to describe the file type, eg: ‘foobar.pdf’

Answer 16

False. Extensions are not required, and if present, do not have to indicate the file type.

Question 17

True or false: In Linux, “Everything is a file”.

Answer 17

True

Question 18

What is the purpose of the program ‘less’?

Answer 18

It is a “pager” used to view text files.

Question 19

With regard to the ‘less’ program, how do you…

Go back one page?

Answer 19

[Page up] or b

Question 20

With regard to the ‘less’ program, how do you…

Go forward one page?

Answer 20

[Page down] or [space]

Question 21

With regard to the ‘less’ program, how do you…

Scroll up one line?

Answer 21

[up arrow]

Question 22

With regard to the ‘less’ program, how do you…

Scroll down one line?

Answer 22

[down arrow]

Question 23

With regard to the ‘less’ program, how do you…

Move to the end of the file?

Answer 23

G

Question 24

With regard to the ‘less’ program, how do you…

Move to the beginning of the file?

Answer 24

1G or g

Question 25

With regard to the ‘less’ program, how do you… Search the file for the next occurrence of *characters*?

Answer 25

/characters

Question 26

With regard to the ‘less’ program, how do you… Search for the next occurrence of the previous search?

Answer 26

n

Question 27

With regard to the ‘less’ program, how do you… Display the help screen?

Answer 27

h

Question 28

With regard to the ‘less’ program, how do you… Quit ‘less’?

Answer 28

q

Question 29

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /

Answer 29

The root directory.

Question 30

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /bin

Answer 30

Binaries that must be present for the system to boot. Fundamental utilities such as ‘ls’ and ‘cp’.

Question 31

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /boot

Answer 31

Contains the kernel, boot loader, and initial RAM disk image (drivers needed at boot time)

Question 32

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /dev

Answer 32

Contains “device nodes”, a list of devices that the kernel understands.

Question 33

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /etc

Answer 33

Contains system-wide configuration files & shell scripts that start system services.

Question 34

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /home

Answer 34

Contains user home directories.

Question 35

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /lib

Answer 35

Contains essential shared libraries used by core system programs.

Question 36

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /lost+found

Answer 36

Used in cases of partial filesystem corruptions.

Question 37

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /media

Answer 37

On modern Linux systems, mount points for removable media devices that are mounted automatically.

Question 38

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /mnt

Answer 38

On older Linux systems, used as a temporary mount point.

Question 39

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /opt

Answer 39

Contains locally installed software, one sub directory per package.

Question 40

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /proc

Answer 40

A virtual filesystem maintained by the kernel that describes how the kernel “sees” the computer.

Question 41

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /root

Answer 41

The home directory for the root user.

Question 42

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /shin

Answer 42

Stands for “system (or super user) binaries” and contains fundamental utilities, usually needed to start, maintain, or recover the system.

Question 43

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /tmp

Answer 43

Contains temporary, transient files not expected to survive a reboot.

Question 44

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr

Answer 44

Contains programs and support files used by regular system users.

Question 45

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/bin

Answer 45

Contains all programs installed by the distribution.

Question 46

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/lib

Answer 46

Contains shared libraries used by programs in /usr/bin

Question 47

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/local

Answer 47

Location where programs not installed by the distribution (but intended for system-wide use) are installed.

Question 48

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/local/bin

Answer 48

Contains programs that are compiled from source code.

Question 49

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/bin

Answer 49

Additional system administration programs

Question 50

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/share

Answer 50

Contains all shared data used by programs in /usr/bin, such as backgrounds, icons, sound files, etc.

Question 51

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /usr/share/doc

Answer 51

Documentation files organized by package

Question 52

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /var

Answer 52

Location where data that is likely to change is stored, for example, databases, spool files, user mail

Question 53

# Define the given directory as described by the Linux Filesystem Hierarchy Standard: /var/log

Answer 53

Contains system log files