Linux Administration, Semester 4(2020), Model examination, July 2022

 SAINTGITS COLLEGE OF APPLIED SCIENCES

PATHAMUTTOM, KOTTAYAM

Model Examination, July 2022

PG Department of Computer Applications and Artificial Intelligence, Semester 4

LINUX ADMINISTRATION

Total : 80 marks Time: 3 hours

Section A

Answer any 6 questions. Each question carries 3 marks.

(Write in not less than a paragraph)

1. What do you mean by open source?

Free and open-source software (FOSS) is software that is both free software and

open-source software where anyone is freely licensed to use, copy, study, and change the

software in any way, and the source code is openly shared so that people are encouraged to

voluntarily improve the design of the software.

2. What is rmdir command ?

rmdir command is used remove empty directories from the file system in Linux.

The rmdir command removes each and every directory specified in the command line only if

these directories are empty. So if the specified directory has some directories or files in it

then this cannot be removed by rmdir command

3. What is wc command?

The wc command stands for “word count” and has a quite simple syntax. It allows us to

count the number of lines, words, bytes, and characters in one or multiple text files. The wc

command in LINUX is a command line utility for printing newline, word and byte

counts for files. It can return the number of lines in a file, the number of characters in a

file and the number of words in a file. It can also be combine with pipes for general counting

operations.

4. Define shell keywords?

Keywords are the words whose meaning has already been explained to the shell.the

keywords cannot be used as variable names because of it is a reserved words with

containing reserved meaning.

Eg:

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echo read set unset

readonly shift export

5. What is the use of read command?

The read command reads one line from standard input and assigns the values of

each field in the input line to a shell variable using the characters in the IFS

(Internal Field Separator) variable as separators.

Example

6. Write any two file test operators.

-e: Returns true value if file exists.

-f: Return true value if file exists and regular file.

-r: Return true value if file exists and is readable.

-w: Return true value if file exists and is writable.

-x: Return true value if file exists and is executable.

-d: Return true value if exists and is a directory.

7. What is su command?

The su command switch the current user to any other user. If you need to run a command

as a different (non-root) user, use the –l [username] option to specify the user account.

Additionally, su can also be used to change to a different shell interpreter on the fly.

8. Define the term root user.

Root is the super user account in Unix and Linux. It is a user account for

administrative purposes, and typically has the highest access rights on the system. Usually,

the root user account is called root

9. Write three permission modes for user files and directories?

Files and directories can have three types of permissions: read, write, and execute:

Someone with read permission may read the contents of a file, or list the contents of a

directory. Someone with write permission may modify the contents of a file, including

adding, changing, or deleting file contents

10. What is mkfs command?

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The mkfs command stands for “make file system” is utilized to make a file system (which

is, a system for organizing a hierarchy of directories, subdirectories, and files) on a

formatted storage device usually, a partition on a hard disk drive (HDD) or it can also be a

USB drive, etc

11. What is DNS.

DNS (Domain Name System) is a fundamental facilitator of several networking

technologies such as mail servers, Internet browsing, and streaming services e.g. Netflix and

Spotify, among others. DNS(Domain Naming System) is an internet service that

translates the domain name to IP address that is understandable by the

computer. For example, the domain name www.domainsystem.com might translate to

198.105. 232.4. This process is the backbone of the internet and very important in the

server.

12. Differentiate grep and egrep.

The difference between grep and egrep is that the grep is a command that allows searching

content according to the given regular expression and displaying the matching lines while

egrep is a variant of grep that allows to search content by applying extended regular

expressions to display the machining lines

(6 x 3 = 18 Marks)

Section B

Answer any 4 questions. Each question carries 8 marks.

(Write in not less than 2 pages)

13. Write a note on Linux architecture.

Architecture of Linux system

The Linux operating system's architecture mainly contains some of the components: the

Kernel, System Library, Hardware layer, System, and Shell utility.

1. Kernel:- The kernel is one of the core section of an operating system. It is responsible

for each of the major actions of the Linux OS. This operating system contains distinct types

of modules and cooperates with underlying hardware directly. The kernel facilitates

required abstraction for hiding details of low-level hardware or application programs to the

system. There are some of the important kernel types which are mentioned below:

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o Monolithic Kernel

o Micro kernels

o Exo kernels

o Hybrid kernels

2. System Libraries:- These libraries can be specified as some special functions. These are

applied for implementing the operating system's functionality and don't need code access

rights of the modules of kernel.

3. System Utility Programs:- It is responsible for doing specialized level and individual

activities.

4. Hardware layer:- Linux operating system contains a hardware layer that consists of

several peripheral devices like CPU, HDD, and RAM.

5. Shell:- It is an interface among the kernel and user. It can afford the services of kernel. It

can take commands through the user and runs the functions of the kernel. The shell is

available in distinct types of OSes. These operating systems are categorized into two

different types, which are the graphical shells and command-line shells.

14. Explain different process scheduling commands in Linux.

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Process Scheduling is an important activity performed by the process manager of the

respective operating system. Scheduling in Linux deals with the removal of the current

process from the CPU and selecting another process for execution.

● at,batch,cron tab,kill commands with example.

15. Explain different mathematical commands in Linux.

Using expr Command

The expr command evaluates expressions and prints the value of provided

expression to standard output. We will look at different ways of using expr for doing

simple math, making comparison, incrementing the value of a variable and finding

the length of a string.

The factor command

As is clear by the name, the factor command in Linux is used to calculate the value

of factors of a number we provide.

Syntax:

$ factor number

The bc command

The bc command is very useful when performing complex operations in the bash.

This command can also make comparisons, handle Booleans, and calculate square

roots, sines, cosines, and tangents, etc. All you need to do is that you pipe the

mathematical expression to the bc command as follows:

$ echo “math_expression” | bc

The output then displays the result of the mathematical expression.

Example:

$ echo "10+10/2-(2*2)" | bc

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16. Write a program to read n numbers using array.

 Program with array concept

17. Write syntax of for loop statement in Linux. Write one example program using for

loop statement.

 syntax

for var in 0 1 2 3 4 5 6 7 8 9

do

echo $var

done

for a in 1 2 3 4 5 6 7 8 9 10

do

    # if a is equal to 5 break the loop

    if [ $a == 5 ]

    then

        break

    fi

    # Print the value

    echo "Iteration no $a"

done

18. Explain different shell variables.

A shell variable is a variable that is available only to the current shell. In contrast, an

environment variable is available system wide and can be used by other applications on the

system.

Variable Types

When a shell is running, three main types of variables are present −

● Local Variables − A local variable is a variable that is present within the current

instance of the shell. It is not available to programs that are started by the shell. They

are set at the command prompt.

● Environment Variables − An environment variable is available to any child process

of the shell. Some programs need environment variables in order to function

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correctly. Usually, a shell script defines only those environment variables that are

needed by the programs that it runs.

● Shell Variables − A shell variable is a special variable that is set by the shell and is

required by the shell in order to function correctly. Some of these variables are

environment variables whereas others are local variables.

19. Write a note configuration files.

A configuration file, also known as a config file, is a local file that controls the

operations of a program, utility or process. Linux configuration files contain the

settings and instructions for different systems, utilities, applications and processes.

20. What are the roles of system administrator?

Duties of a Linux Administrator:

 System Administration has become a solid criterion for an organization and institute that

requires a solid IT foundation. Hence, the need for efficient Linux administrators is the

requirement of the time. The job profile might change from each organization as there may

be added responsibilities and duties to the role. Below are some duties of a Linux

Administrator:

● Maintain all internet requests inclusive to DNS, RADIUS, Apache, MySQL, PHP.

● Taking regular back up of data, create new stored procedures and listing back-up is one

of the duties.

● Analyzing all error logs and fixing along with providing excellent customer support for

Webhosting, ISP and LAN Customers on troubleshooting increased support troubles.

● Communicating with the staff, vendors, and customers in a cultivated, professional

manner at all times has to be one of his characteristics.

● Enhance, maintain and creating the tools for the Linux environment and its users.

● Detecting and solving the service problems ranging from disaster recovery to login

problems.

● Installing the necessary systems and security tools. Working with the Data Network

Engineer and other personnel/departments to analyze hardware requirements and

makes acquiring recommendations.

● Troubleshoot, when the problem occurs in the server.

21. Write a note on Apache Server.

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● Apache HTTP Server is a free and open-source web server that delivers web

content through the internet. It is commonly referred to as Apache and after

development, it quickly became the most popular HTTP client on the web.

● Advantages and disadvantages

● Apache is considered open source software, which means the original source code is

freely available for viewing and collaboration. Being open source has made Apache

very popular with developers who have built and configured their own modules to

apply specific functionality and improve on its core features.

● One of the pros of Apache is its ability to handle large amounts of traffic with

minimal configuration. It scales with ease and with its modular functionality at its

core, you can configure Apache to do what you want, how you want it. You can also

remove unwanted modules to make Apache more lightweight and efficient.

(4 x 8 = 32 Marks)

Section C

Answer up to 3 questions carrying 15 marks each. However, total marks for this

section should not exceed 30 marks. Marks scored over 30 will be ignored

22. Explain Linux file system in detail.

A Linux file system is a structured collection of files on a disk drive or a partition. A

partition is a segment of memory and contains some specific data. In our machine,

there can be various partitions of the memory. Generally, every partition contains a

file system.

Linux file system contains two-part file system software implementation architecture.

Consider the below image:

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In Linux, the file system creates a tree structure. All the files are arranged as a tree

and its branches. The topmost directory called the root (/) directory. All other

directories in Linux can be accessed from the root directory.

o Specifying paths: Linux does not use the backslash (\) to separate the components; it

uses forward slash (/) as an alternative. For example, as in Windows, the data may

be stored in C:\ My Documents\ Work, whereas, in Linux, it would be stored in /home/

My Document/ Work.

o Partition, Directories, and Drives: Linux does not use drive letters to organize the drive

as Windows does. In Linux, we cannot tell whether we are addressing a partition, a

network device, or an "ordinary" directory and a Drive.

o Case Sensitivity: Linux file system is case sensitive. It distinguishes between

lowercase and uppercase file names. Such as, there is a difference between test.txt

and Test.txt in Linux. This rule is also applied for directories and Linux commands.

o File Extensions: In Linux, a file may have the extension '.txt,' but it is not necessary

that a file should have a file extension. While working with Shell, it creates some

problems for the beginners to differentiate between files and directories. If we use the

graphical file manager, it symbolizes the files and folders.

o Hidden files: Linux distinguishes between standard files and hidden files, mostly the

configuration files are hidden in Linux OS. Usually, we don't need to access or read

the hidden files. The hidden files in Linux are represented by a dot (.) before the file

name (e.g., .ignore). To access the files, we need to change the view in the file

manager or need to use a specific command in the shell.

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Types of Linux File System

When we install the Linux operating system, Linux offers many file systems such

as Ext, Ext2, Ext3, Ext4, JFS, ReiserFS, XFS, btrfs, and swap.

 Boot block,super block,inode block,data block

23. Differentiate background and foreground processes with related commands.

1. Background processes typically run with little or no user interaction, they interact

with the system instead. Foreground processes are what the user interacts with.

2. Background processes, unless explicitly ran so, run with non-admin permissions.

This is also called batch processing.

3. A foreground process has access to the terminal (standard input and output),

while the background process does not.

4. A background process runs without being connected to your keyboard. If the

background process requires any keyboard input, it waits.

The basic advantage of background processing is that it allows the system to run

other commands; the processor does not have to wait until it completes one task to

start another. This provides the ability to have multiple applications executing at the

same time. For example, a user can play a game with one application while another

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application is playing a song. To the developer, the advantage of multitasking gives

the ability to create tools and applications which use more than one process and to

create processes that use multiple threads of execution.

24. Explain various shells and shell programming in bash.

SHELL is a program which provides the interface between the user and an

operating system. When the user logs in OS starts a shell for user.

Types of Shell:

 The C Shell –

Denoted as csh

Bill Joy created it at the University of California at Berkeley. It incorporated

features such as aliases and command history. It includes helpful programming

features like built-in arithmetic and C-like expression syntax.

The Bourne Shell –

Denoted as sh

It was written by Steve Bourne at AT&T Bell Labs. It is the original UNIX

shell. It is faster and more preferred. It lacks features for interactive use like

the ability to recall previous commands. It also lacks built-in arithmetic and

logical expression handling. It is default shell for Solaris OS.

The Korn Shell

It is denoted as ksh

It Was written by David Korn at AT&T Bell LabsIt is a superset of the Bourne

shell.So it supports everything in the Bourne shell.It has interactive features.

It includes features like built-in arithmetic and C-like arrays, functions, and

string-manipulation facilities.It is faster than C shell. It is compatible with

script written for C shell.

etc

25. List out various filter commands with example.

1.Awk Command

Awk is a remarkable pattern scanning and processing language, it can be used to build useful

filters in Linux.

2. Sed Command

sed is a powerful stream editor for filtering and transforming text.

3. Grep, Egrep, Fgrep, Rgrep Commands

These filters output lines matching a given pattern. They read lines from a file or standard

input, and print all matching lines by default to standard output.

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-

4. head Command

head is used to display the first parts of a file, it outputs the first 10 lines by default. You

can use the -n num flag to specify the number of lines to be displayed:

/ Learn how to use head command with tail and cat commands for effective usage in Linux.

5. tail Command

tail outputs the last parts (10 lines by default) of a file. Use the -n num switch to specify the

number of lines to be displayed.

6. sort Command

sort is used to sort lines of a text file or from standard input.

▪

7. uniq Command

uniq command is used to report or omit repeated lines, it filters lines from standard input

and writes the outcome to standard output.

After running sort on an input stream, you can remove repeated lines with uniq 

3.linuxsay.com

4.windowsmint.com

9. pr Command

pr command converts text files or standard input for printing.

10. tr Command

This tool translates or deletes characters from standard input and writes results to standard

output.

11. more Command

more command is a useful file perusal filter created basically for certificate viewing

12. less Command

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