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Top 26 Red Hat Linux System Administration Interview Questions

Q1. What Is Soft Link?

Soft link is a technique to create quick cuts in linux. It is similar to home windows brief cut feature.

Q2. How To Determine The Hostname Of A Linux Box?

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

Q3. What Is Selinux?

SELinux is an acronym for Security-improved Linux. It is an get admission to manipulate implementation and protection function for the Linux kernel. It is designed to protect the server against misconfigurations and/or compromised daemons. It placed limits and instructs server daemons or packages what documents they could get right of entry to and what movements they can take via defining a safety policy.

Q4. How To Check The Default Gatway?

Using ‘route -n’ command we will determine the default gateway in linux.

Q5. What Is A Process?

Any application in execution is referred to as a system.

Q6. How To Change The Password Of User From The Command Line?

‘passwd <User-Name>’

Q7. How To Check The Current Runlevel Of A Linux Box?

‘who -r’ and ‘runlevel’ , each of these command are used to find current run degree.

Q8. What Is The Functionality Of A Puppet Server?

Puppet is an open-supply and organisation application for configuration management toll in UNIX like running gadget. Puppet is an IT automation software used to push configuration to its clients (puppet marketers) the usage of code. Puppet code can do an expansion of duties from installing new software program, to check record permissions, or updating person bills and lots of different responsibilities.

Q9. How To List Hidden Files From The Command Line?

‘ls -a’ <Folder_Name>

Q10. Which Command Is Used To Check The Kernel Version ?

‘uname -r’

Q11. What Is Crontab And Explain The Fields In A Crontab ?

The cron is a deamon that executes commands at unique dates and instances in linux. You can use this to agenda activities, both as one-time occasions or as ordinary tasks. Crontab is the program used to install, deinstall or list the tables used to force the cron daemon in a server. Each person will have their own crontab, and even though those are documents in /var/spool/cron/crontabs, they're not meant to be edited without delay. Here are few of the command line alternatives for crontab.

Crontab -e Edit your crontab report.

Crontab -l Show your crontab record.

Crontab -r Remove your crontab report.

Traditional cron format includes six fields separated with the aid of white areas:

The layout is explained in element beneath variety variety: 1-7, 1 standing range variety +———- Hour (variety: zero-23)

+———— Minute (range: zero-fifty nine)

Q12. What Are The Run Levels In Linux And How To Change Them?

A run level is a kingdom of init and the whole device that defines what machine offerings are operating and they may be recognized through numbers.There are 7 exceptional run tiers present (run degree 0-6) in Linux system for exceptional reason. The descriptions are given underneath.

0: Halt System (To shutdown the machine)

1: Single person mode

2: Basic multi user mode without NFS

three: Full multi person mode (textual content primarily based)

4: unused

5: Multi consumer mode with Graphical User Interface

6: Reboot System

To exchange the run degree, edit the report “/etc/inittab” and exchange initdefault access ( id:five:initdefault:). If we want to exchange the run degree on the fly, it may be performed using ‘init’ command.

For example: when we type ‘init 3′ within the commandline , this can pass the system from modern runlevel to runlevl @Current degree may be indexed with the aid of typing the command ‘who -r’.

Q13. What Is The Default Uid & Gid Of Root User?

Default uid & gid of root user is zero.

Q14. How To Check The Uptime Of A Linux Server?

Using uptime command we can decide how long a linux container has been going for walks , also uptime can be viewed via the pinnacle & w command.

Q15. What Is Initrd ?

Initrd stands for initial ram disk , which contains the transient root filesystem and neccessary modules which helps in mounting the actual root filesystem in study mode most effective.

Q16. How To Check All The Installed Kernel Modules?

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

Q17. What Is Name Of First Process In Linux?

‘init’ is the first manner in linux which is started out by kernel and whose pid is 1.

Q18. Why Linux Is Called Opensource?

Because One can customise the prevailing code and might redistribute it.

Q19. How To Create A Blank File In Linux From Command Line ?

Using the command ‘contact <file-name>’

Q20. How To Check Which Redhat Version Is Installed On Server?

Use the command cat /and so forth/redhat-launch , output of this command will inform you the redhat version.

Q21. How To Install Rpm Packages In Redhat & Centos Linux ?

Rpm and yum command are used to install programs in redhat linux and CentOS.

Q22. What Is Run Level 2?

Run stage 2 is the multi-user mode with out networking.

Q23. What Is The Difference Between Umask And Ulimit ?

Umask stands for ‘User document advent masks’, which determines the settings of a mask that controls which record permissions are set for files and directories while they're created. While ulimit is a linux constructed in command which affords manage over the resources available to the shell and/or to procedures commenced by way of it.

You can restriction user to particular variety by using editing /and many others/security/limits.Conf on the same time machine extensive settings can be up to date in /and so on/sysctl.Conf

Q24. How To Check The Ip Address Of Lan Card?

Using ‘ifconfig’ & ‘ip deal with’ command we can decide the ip deal with of LAN Card.

Q25. What Is Bootloader?

Bootloader is a program that boots the running system and comes to a decision from which kernel OS will boot.

Q26. What Are Inodes In Linux ? How To Find The Inode Associated With A File ?

An inode is a facts shape on a filesystem on Linux and different Unix-like working systems that stores all the information about a document besides its name and its real information. When a document is created, it is assigned both a name and an inode variety, which is an integer that is unique inside the filesystem. Both the file names and their corresponding inode numbers are stored as entries in the directory that appears to the user to incorporate the documents. The concept of inodes is particularly important to the restoration of damaged filesystems. When elements of the inode are lost, they seem within the lost+observed listing inside the partition in which they as soon as existed.

The following will display the name of every object inside the contemporary directory collectively with its inode quantity:

# ls -i

The avialble variety inodes in a filesystem may be determined the use of the underneath command :

# df -i

The different manner we are able to get the inode info of a record by way of the use of the stat commmand.

Usage : # stat

Example :

-sh-four.1$ stat be aware.Txt

File: `word.Txt'

Size: 4 Blocks: 8 IO Block: 4096 everyday report

Device: fd05h/64773d Inode: 8655235 Links: 1

Access: (0644/-rw-r--r--) Uid: (69548/nixuser) Gid: (25000/ UNKNOWN)