Linux Technical Interview Questions Part-4

Linux Technical Interview Questions Part-4

151. What are a few commands you would run if your system is running

slow?

top, iostat, df –h, netstat etc.

152. How to install a package in Redhat Linux?

yum install packagename

153. What is the difference between “ifconfig” and “ipconfig”

commands?

ifconfig for Linux and ipconfig for Windows

154. What is the first line written in a shell script?

Define shell

e.g. #!/bin/bash

155. Where is the network (Ethernet) file located, please provide

exact directory location and file name?

/etc/sysconfig/network-scripts/ifcfg-nic

156. Why do we use “last” command?

To see who has logged in the system whether active or logged off

157. What is RHEL Linux stands for?

Search online

158. To view your command history, which command is used and how to

run a specific command?

history and history #

159. What is NTP and briefly explain how does it work and where is the

config files and related commands of NTP?

Search online

160. How to disable firewall in Linux?

Search online

161. How to configure mail server relay for sendmail service?

Edit /etc/mail/sendmail.mc file and add SMART_HOST entry

162. Where is samba log file located?

/var/log/samba

163. What is mkfs command used for?

To create a new filesystem

164. If you create a new group, which file does it get created in?

/etc/group

165. Which file has DNS server information (e.g. DNS resolution)?

/etc/resolv.conf

166. What are the commands you would run if you need to find out the

version and build date of a package (e.g. http)?

rpm –qi http

167. On the file permissions? What are the first 3 bits for and who is

it for?

Read, write and execute. They are used for the owner of the file

168. How to create a soft link?

ln –s

169. How to write a script to delete messages in a log file older than

30 days automatically?

Search online

170. How to quit out of “man” command?

q

171. Which command is used to partition disk in Linux?

fdisk

172. What is the difference between “shutdown” and “halt” command?

Search online

173. What is the exact syntax of mounting NFS share on a client and

also how to un-mount?

Search online

174. What experience do you have with scripting, explain?

if-the, do-while, case, for loop scripts

175. How to get information on all the packages installed on the

system?

rpm –qa

176. Explain VMWare?

Search online

177. You are tasked to examine a log file in order to find out why a

particular application keep crashing. Log file is very lengthy,

which command can you use to simplify the log search using a

search string?

grep for error, warning, failure etc. in /var/log/messages file

178. What is /etc/fstab file and explain each column of this file?

Search online

179. What the latest version of Windows server?

Search online

180. What is the exact command to list only the first 2 lines of

history output?

history | head -2

181. How to upgrade Linux from 7.3 to 7.4?

yum install update

182. How to tell which shell you are in or running?

$0

183. You have tried to “cd” into a directory but you have been denied.

You are not the owner of that directory, what permissions do you

need and where?

- - - - - - - r – x

184. What is CNAME record in DNS?

Entry for hostname to hostname

185. What is the name of VMWare operating system?

ESXi

186. What is the client name used to connect to ESXi or vCenter

server?

vSphere client

187. You get a call from a user saying that I cannot write to a file

because it says, permission denied. The file is owned by that

user, how do you troubleshoot?

Give write permission on the first 3 bits

188. What is the latest version of VMWare?

Search online

189. What is the name of firewall daemon in Linux?

firewalld

190. Which command syntax you can use to list only the 20th line of a

file?

Search online

191. What is the difference between run level 3 and 5?

3 = Boot system with networking, 5 = boot system with networking

and GUI

192. List a few commands that are used in troubleshooting network

related issue?

netstat, tcpdump etc.

193. What is the difference between domain and nameserver?

Search online

194. You open up a file and it has 3000 lines and it scrolled up

really fast, which command you will use to view it one page at a

time?

more or less

195. How to start a new shell. E.g. start a new ksh shell?

Simply type ksh, or bash

196. How to kill a process?

kill processID

197. How to check scheduled jobs?

crontab –l

198. How to check system memory and CPU usage?

free and top

199. Which utility could you use to repair the corrupted file system?

fsck

200. What is the command to make a service start at boot?

systemctl enable servicename

201. How to combine 2 files into 1? E.g. you 3 lines in file “A” and 5

lines in file “B”, which command syntax to use that will combine

into one file of 3+5 = 8 lines

cat fileA >> fileB

202. What is echo command used for?

To output to a screen

203. What does the following command do?

echo This year the summer will be great > file1

It will create a new file “file1” with the content as “This year

the summer will be great”

204. Which file to modify to allow users to run root commands

/etc/sudoers

205. You need to modify httpd.conf file but you cannot find it, Which

command line tool you can use to find file?

find / -name “httpd.conf”

206. Your system crashed and being restarted, but a message appears,

indicating that the operating system cannot be found. What is the

most likely cause of the problem?

The /boot file is most likely corrupted