General Questions

Question 1

What is Linux?

Answer 1

Linux is an operating system based on UNIX, and was first introduced by Linus Torvalds. It is based on the Linux Kernel, and can run on different hardware platforms manufactured by Intel, MIPS, HP, IBM, SPARC and Motorola. Another popular element in Linux is its mascot, a penguin figure named Tux

Question 2

What is the difference between UNIX and LINUX?

Answer 2

Unix began as a propriety OS and was developed at Bell Labs. Linux is open source

Question 3

What is BASH?

Answer 3

Bourne Again Shell written by Steve Bourne as a replacement to Bourne Shell. It combines all the features from the original version of Bourne Shell, plus additional functions to make it easier and more convenient to use.

Question 4

What is Linux Kernel?

Answer 4

The Linux Kernel is a low-level systems software whose main role is to manage hardware resources for the user. It is also used to provide an interface for user-level interaction

Question 5

What is LILO?

Answer 5

LILO is a boot loader for Linux. It is used mainly to load the Linux operating system into main memory so that it can begin its operations.

Question 6

What is a swap space?

Answer 6

A swap space is a certain amount of space used by Linux to temporarily hold some programs that are running concurrently. This happens when RAM does not have enough memory to hold all programs that are executing.

Question 7

What is the advantage of open source?

Answer 7

Open source allows you to distribute your software, including source codes freely to anyone who is interested. People would then be able to add features and even debug and correct errors that are in the source code. They can even make it run better, and then redistribute these enhanced source code freely again. This eventually benefits everyone in the community.

Question 8

What are the basic components of Linux?

Answer 8

ust like any other typical operating system, Linux has all of these components: kernel, shells and GUIs, system utilities, and application program. What makes Linux advantageous over other operating system is that every aspect comes with additional features and all codes for these are downloadable for free.

Question 9

What is the basic difference between BASH and DOS?

Answer 9

The key differences between the BASH and DOS console lies in 3 areas:

• BASH commands are case sensitive while DOS commands are not;
• under BASH, / character is a directory separator and \ acts as an escape character. Under DOS, / serves as a command argument delimiter and \ is the directory separator
• DOS follows a convention in naming files, which is 8 character file name followed by a dot and 3 character for the extension. BASH follows no such convention

Question 10

Describe the root account

Answer 10

The root account is like a systems administrator account, and allows you full control of the system. Here you can create and maintain user accounts, assigning different permissions for each account. It is the default account every time you install Linux

Question 11

What is CLI?

Answer 11

CLI is short for command line interface. This interface allows users to type declarative commands to instruct the computer to perform operation. CLI offers an advantage in that there is greater flexibility.

Question 12

What is GUI?

Answer 12

Graphical User Interface. The use of graphical elements makes it easier to interact with the system.

Question 13

How do you open a command prompt when issuing a command?

Answer 13

Launch a terminal app.

Question 14

How can you find out how much memory Linux is using?

Answer 14

cat /proc/meminfo for memory usage info.

Question 15

How do you refer to the parallel port where devices such as printers are connected?

Answer 15

you refer to it as /dev/lp. So LPT1 would be referred to as /dev/lp0

Question 16

Are drives such as harddrive and floppy drives represented with drive letters?

Answer 16

No. In Linux, each drive and device has different designations. EX: /dev/fd0, /dev/fd1 for floppy drives and for IDE/EIDE hard drives are referred to as /dev/hda, /dev/hdb…

Question 17

How do you change permissions under Linux?

Answer 17

chmod go+r filename to give read permissions to group and others

Question 18

In Linux, what names are assigned to the different serial ports?

Answer 18

Serial ports are identified as /dev/ttyS0 to /dev/ttyS7.

Question 19

How do you access partitions under Linux?

Answer 19

Linux assigns numbers at the end of the drive identifier. EX: if hard drive had three primary partitions, then you would name and number as /dev/hda1, /dev/hda2, /dev/hda3

Question 20

What are hard links?

Answer 20

Hard links are multiple references/links to same inode. Each hard link takes up an entry in the inode table.

Question 21

What is the maximum length for a filename under Linux?

Answer 21

Any filename can have a maximum of 255 characters. This limit does not include the pathname.

Question 22

What are filenames that are preceded by a dot?

Answer 22

They are hidden files. These files can be configuration or script files. It makes it less likely to be accidentally deleted.

Question 23

Explain Virtual desktop

Answer 23

Using virtual desktop, each desktop is a clean slate where you can open one or more programs. Rather than minimizing/restoring all those program as needed, you can simply shuffle between virtual desktops.

Question 24

How do you share a program across different virtual desktops under Linux?

Answer 24

To share a program across different virtual desktops, in the upper left-hand corner of a program window look for an icon that looks like a pushpin. Pressing this button will “pin” that application in place, making it appear in all virtual desktops, in the same position onscreen.

Question 25

What does a nameless (empty) directory represent?

Answer 25

This empty directory name serves as the nameless base of the Linux file system. This serves as an attachment for all other directories, files, drives and devices. IE: for mounting or mount point

Question 26

What is the pwd command?

Answer 26

present working directory

Question 27

What are daemons?

Answer 27

Daemons are services that runs in the background. After the service is done, it disconnects and waits for further requests.

Question 28

What are the kinds of permissions under Linux?

Answer 28

Read, write and execute.

Question 29

What are environment variables?

Answer 29

Environment variables are global settings that control the shell’s function and linux programs.

Question 30

What are the contents in /usr/local?

Answer 30

It usually contains installed files.

Question 31

How do you terminate an ongoing process?

Answer 31

kill -9 pid or kill 0 to terminate all process at once.

Question 32

What is command grouping and how does it work?

Answer 32

You can use parentheses to group commands. For example, if you want to send the current date and time along with the contents of a file named OUTPUT to a second file named MYDATES, you can apply command grouping as follows: (date; cat OUTPUT) > MYDATES

Question 33

How do you execute more than one command or program from a single command line entry?

Answer 33

Use semicolon after each command

Question 34

Write a command that will look for files with an extension “c”, and has the occurrence of the string “apple” in it

Answer 34

find . -name “*.c” | xargs grep -i “apple”

Question 35

Write a command that will do the following:

• look for all files in the current and subsequent directories with an extension c,v;
• strip the,v from the result (you can use sed command)
• use the result and use a grep command to search for all occurrences of the word ORANGE in the files.

Answer 35

find . -name “*.c,v” | sed ‘s/,v//g’ | grep “ORANGE”

Question 36

What port is ssh service?

Answer 36

port 22

Question 37

What port is telnet service?

Answer 37

Port 23

Question 38

What port is smtp service?

Answer 38

Port 25, and 465 for SMTP over SSL

Question 39

What port is POP service?

Answer 39

Port 110 and 995 for pop3s SSL

Question 40

What port is mySQL service?

Answer 40

Port 3306

Question 41

What port is https service?

Answer 41

443

Question 42

How do you output the last line of a file?

Answer 42

-tail -1 filename

Question 43

How do you change the kernel state during runtime?l

Answer 43

sysct

Question 44

How do you substitute string1 with string2 in multiple files that contains string1?

Answer 44

find . -type f -exec sed -i ‘’ “s/string1/string2/g” {} \;

Question 45

How do you display information about processes with the most CPU usage?

Answer 45

top -o cpu

Question 46

How can you find out how many current cron jobs are on the system?

Answer 46

Login as root and list what’s in /var/spool/cron