Top interview question and answers for Linux administrator Part - 2

                       

Q:21 How to upgrade Kernel in Linux ?

Ans: We should never upgrade Linux Kernel , always install the new New kernel using rpm command because upgrading a kenel can make your linux box in a unbootable state.

Q:22 How To scan newly asssigned luns on linux box without rebooting ?

Ans: There are two ways to scan newly assigned luns :
Method:1 if sg3 rpm is installed , then run the command ‘rescan-scsi-bus.sh’
Method:2 Run the Command ,  echo ” – – – ” > /sys/class/scsi_host/hostX/scan

Q:23 How  to find WWN numbers of HBA cards in Linux Server ?

Ans: We can find the WWN numbers of HBA cards using the command ‘systool -c fc_host -v | grep port_name’

Q:24 How to add & change the Kernel parameters ?

Ans: To Set the kernel parameters in linux , first edit the file ‘/etc/sysctl.conf’ after making the changes save the file and run the command ‘sysctl -p’ , this command will make the changes permanently without rebooting the machine.

Watch Linux question and answers video

 

Q:25 What is Puppet Server ?

Ans: Puppet is an open-source & enterprise software for configuration management toll in UNIX like  operating system.  Puppet is a  IT automation software used to push configuration to its clients (puppet agents) using code. Puppet code can do a variety of tasks from installing new software, to check file permissions, or updating user accounts & lots of other tasks.

Q:26 What are manifests in Puppet ?

Ans: Manifests in Puppet are the files in which the client configuration is specified.

Q:27 Which Command is used to sign requested certificates in Puppet Server ?

Ans: ‘puppetca  –sign hostname-of-agent’ in (2.X)  & ‘puppet ca  sign hostname-of-agent’ in  (3.X)

Q:28  At which location  Puppet Master Stores Certificates ?

Ans:  /var/lib/puppet/ssl/ca/signed

Q:29 How to find all the regular files in a directory  ?

Ans: using the command ‘find /<directory -type f’.

Q:30 What is load average in a linux ?

Ans: Load  Average is defined as the average sum of the number of process waiting in the run queue and number of process currently executing over the period of 1,5 and 15  minutes. Using the ‘top’ and ‘uptime’ command we find the load average of a linux sever.

Q:31 How To check the uptime of a Linux Server ?

Ans: Using uptime command we can determine how long a linux box has been running , also uptime can be viewed by the top & w command.

Q:32 How to check which Redhat version is installed on Server ?

Ans: Use the command cat /etc/redhat-release , output of this command will tell you the redhat version.

Q:33 How to install rpm packages in Redhat & CentOS linux ?

Ans: rpm and yum command are used to install packages in redhat linux and CentOS.

Q:34 How to check the ip address of LAN Card ?

Ans: Using ‘ifconfig’ & ‘ip address’ command we can determine the ip address of LAN Card.

Q:35 How to determine the hostname of a linux box ?

Ans: On typing the hostname command on terminal we can determine the hostname of a linux server.

Q:36 How To check the default gatway ?

Ans: Using ‘route -n’ command we can determine the default gateway in linux.

Q:37 Which Command is used to check the kernel Version ?

Ans: ‘uname -r’

Q:38 How to check the current runlevel of a linux box ?

Ans : ‘who -r’ and ‘runlevel’ , both of these command are used to find current run level.

Q:39 What is Initrd ?

Ans: Initrd stands for initial ram disk , which contains the temporary root filesystem and neccessary modules which helps in mounting the real root filesystem in read mode only.

Q:40 What is Bootloader ?

Ans: Bootloader is a program that boots the operating system and decides from which kernel OS will boot.

Q:41 How to list hidden files from the command line ?

Ans: ‘ls -a’ <Folder_Name>

Q:42 What is soft link ?

Ans: Soft link is a method to create short cuts in linux. It is similar to windows short cut feature.

Q:43 How to create a blank file in linux from command line ?

Ans: Using the command ‘touch <file-name>’

Q:44 What is run level 2 ?

Ans: Run level 2 is the multi-user mode without networking.

Q:45 Why linux is called OpenSource ?

Ans: Because One can customize the existing code and can redistribute it.

Q:46 How to check all the installed Kernel modules ?

Ans: Using the Command ‘lsmod’ we can see the installed kernel modules.

Q:47 What is the default uid & gid of root user ?

Ans: Default uid & gid of root user is 0.

Q:48 How To change the password of user from the Command Line ?

Ans: ‘passwd <User-Name>’

Q:49 What is a Process ?

Ans: Any program in execution is called a process.

Q:50 What is name of first process in linux ?

Ans: ‘init’ is the first process in linux which is started by kernel and whose pid is 1.