tag:blogger.com,1999:blog-52363515752152315482024-03-05T16:42:27.046+05:30Linux & DevOPSLearning Portal for Cloud, DevOPS, AWS, Kubernetes, Docker, Ansible, Interview Question Answers etc..Unknownnoreply@blogger.comBlogger120125tag:blogger.com,1999:blog-5236351575215231548.post-83169479515244754412020-03-02T11:47:00.000+05:302020-05-04T21:54:40.235+05:30How to change time zone in RHEL 7
How to change time zone in RHEL 7
Way to change a timezone on CentOS 7 RHEL7 Linux server
You should use "timedatectl" to change time zone in RHEL-7
Syntax :-
$ timedatectl set-timezone {timezone}
E.g.
$ timedatectl set-timezone America/Los_Angeles
To List all available time zones
[root@amitmaheshwari ~]# timedatectl list-timezones
You can use grep to search forUnknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-41917457510243642172020-02-21T13:46:00.000+05:302020-02-21T13:46:09.381+05:30Docker Interview Questions and Answers
25 Important Docker Interview Questions and Answers
Following are frequently asked Docker job interview questions for fresher as well as experienced DevOps engineers.
Q1. What is Docker?
Docker is an open-source lightweight containerization technology. It has gained widespread popularity in the cloud and application packaging world. It allows you to automate the deployment of Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-82545257159876707252020-02-18T16:09:00.000+05:302020-02-18T16:11:16.542+05:30Kubernetes Interview Questions and Answers 2019 2020
Kubernetes Interview Questions and Answers
Interview Kubernetes engine
Top 25 Kubernetes Interview Questions You Must Prepare In 2019 & 2020
Q1 :- What is Kubernetes?
Kubernetes is an open-source container management tool which holds the responsibilities of container deployment, scaling & descaling of containers & load balancing. Being the Google’s brainchild, it Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-4824824607098649502020-02-17T11:43:00.001+05:302020-02-17T11:43:02.307+05:30OpenStack Interview Questions and Answers
OpenStack Interview Questions and Answers
Here is a list of Important OpenStack Interview Question and Answers.
OpenStack Identity Management
How would you add the user apressuser with a Member role to the apress project?
A. openstack role add –project apress –user apressuser _member_
B. openstack role add –project apress –user apressuser member
C. openstack role add –project Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-15367899152633728872020-02-12T10:20:00.000+05:302020-04-14T11:06:47.449+05:30Sendmail Server Interview Questions
Sendmail Server Interview Questions And Answers
Here is a list of 30 Important sendmail server Interview Questions :
Q 1: - How to start sendmail server ?
service sendmail restart
Q 2: - On which ports sendmail and senmail with SSL works ?
By default, Sendmail uses TCP and UDP port 25 for non-encrypted transfers. If the
Sendmail server is configured to use SSL for encrypting email Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-37579252891783668802020-02-12T09:58:00.000+05:302020-02-12T09:58:32.884+05:30What Happens when you execute a program
Linux Interview Question :- What Happens when you execute a program ?
When you execute a program on your UNIX system, the system
creates a special environment for that program.
This environment contains everything needed for the system
to run the program as if no other program were running on the system. Each
process has process context, which is everything that is unique about the Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-67119274429763883812020-02-12T09:57:00.000+05:302020-02-12T09:57:01.901+05:30SSH login without password
SSH login without password or Keybased Authentication
password less ssh
Problem : SSH login without password
You want to use Linux and OpenSSH to automate your tasks. Therefore you need an automatic login
from host A(amitmaheshwari.in) user "tom" --> to Host B (xyz.com) user "jim".
You don't want to enter any passwords, because you want to call ssh from a Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-36449869727494290082020-02-12T09:54:00.000+05:302020-02-12T09:54:27.504+05:30What Happens when you execute a command
What Happens when you execute a command ?
When you enter ‘ls’
command to look at the contents of your current working directory,
UNIX does a series of things to create an environment for ls and the run it:
The shell has UNIX
perform a fork.
This creates a new process that the shell will use to run the ls program. The shell has UNIX perform
an exec of the ls program.&Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-2611853392166206282020-02-12T09:53:00.000+05:302020-02-12T09:53:44.713+05:30How to install iostat, mpstat, vmstat commands in Linux
How to install iostat, mpstat, vmstat commands in linux
By installing sysstat package we can get the "iostat" and "mpstat" commands.
Following commands will be installed by systat package (rpm)
iostat, mpstat, vmstat, pidstat, sar, cifsiostat
[root@amitmaheshwari.in ~]# yum list | grep sysstat
sysstat.x86_64 &Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-4032969600903116922020-02-12T09:52:00.000+05:302020-02-12T09:52:39.238+05:30What are the fields in the etc passwd file
Linux Interview Questions: - What are the fields in the “/etc/passwd” file?
It contains all the information of the users who log into
the system. It contains a list of the system's accounts, giving for each
account some useful information like user ID, group ID, home directory, shell,
etc. It should have general read permission as many utilities, like ls use it
to map user IDs to user names,Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-73277337911163330992020-02-12T09:51:00.000+05:302020-02-12T09:51:03.037+05:30How To Add Static Routes In Linux
Process to add static route in RHEL 7 or RHEL 8
Adding Static Routes On Various *NIX (Linux,AIX,HP-UX)
Static routes are generally required for traffic that must not, or should not, go through the default gateway. In this article we will discuss how to add static routes in variox nix.
Scenario : Suppose if you want that all the traffic to network 172.168.102.0/24 should use Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-80656402253897078772020-02-12T09:46:00.000+05:302020-02-12T09:46:50.203+05:30Find Out Top 10 Memory and CPU Consuming Processes in linux
Find Out Top 10 Memory and CPU Consuming Processes in linux
for memory:
ps auxf | sort -nr -k 4 | head
sample output:
[root@amitmaheshwari.in ~] # ps auxf | sort -nr -k 4 | head
daemon 10566 2.5 4.2 238580 169756 ? S 14:22 1:23 Rails: /opt/redmine-2.1.2-1/apache2/htdocs/../../apps/redmine/htdocs Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-59846326733487702332020-02-06T12:32:00.002+05:302020-02-06T15:01:49.501+05:30Linux sar command Tutorial
Linux sar (System Activity Reporter) command Guide and Tutorial with Example
Installation of sar (System Activity Reporter)
As noted, sar is a component of the sysstat package, which is already contained in numerous distribution files and can be easily installed, depending on the distribution file, either by yum install sysstat (RHEL Based OS) or apt-get install sysstat (Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-30844956936722744212020-02-05T19:57:00.004+05:302020-02-05T19:57:39.562+05:30Introduction to Kubernetes Networking
Here we are introducing Kubernetes networking.
This is meant to be an introduction into Kubernetes networking and I assume you have a basic understanding of Kubernetes pods and Kubernetes service and their use cases.
Before we can understand Kubernetes networking we must first understand what we are trying to solve. There are 3 issues we need to solve in a Kubernetes cluster:
Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-20781100989032791262020-02-05T15:17:00.000+05:302020-02-05T15:17:01.539+05:30Basic Concept of Kubernetes
Introduction to Basic Concept of Kubernetes
What is Kubernetes?
Kubernetes
is an open-source platform/tool created by Google. It is written in GO-Lang. So
currently Kubernetes is an open-source project under Apache 2.0 license.
Sometimes in the industry, Kubernetes is also known as “K8s”. With Kubernetes, you can
run any Linux container across private, public, and hybrid cloud Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-86107886047464898312020-02-05T08:08:00.000+05:302020-04-14T11:15:57.762+05:30SSH Interview Questions
SSH Interview Questions and answers
Q:1 What is the default port & configuration file of SSH Server ?
Ans: 22 is default port for ssh and ‘/etc/ssh/sshd_config’ is the configuration file.
Q:2 How to change the default ssh port in linux ?
Ans: To change the port , first edit the file ‘ /etc/ssh/sshd_config ‘ , change the vaule of parameter ‘ port 22 ‘, now Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-89513566999430728202020-01-01T16:51:00.000+05:302020-03-09T12:16:51.504+05:30Important Port numbers for the Linux system administrator
This is an important question mostly asked during Linux Interview.
To understanding the ports, their details and numbers, I have collected some info.
Linux Important Ports information
FAQ related to PORTS in Linux !!
Q. What is a port?
A port is piece of software which is used as docking point in your machine, where remote application can communicate. This is analogy to the Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-53495760782418496652019-12-05T16:27:00.002+05:302019-12-05T16:27:32.172+05:30How to boot RHEL 7 and CentOS 7 into Rescue Mode
Booting RHEL 7 and CentOS 7 into Rescue Mode
Step 1 – At the Grub2 boot menu type e to edit the grub config. Note: Depending on you environment you may have to type p first and enter a grub password before having the permissions to edit the grub config. Step 2 – Locate the first line that beings with linux16. Use the END Key or the arrow keys to go to the end of that line. I my example the Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-38677399708310419882019-12-05T10:15:00.000+05:302019-12-05T10:15:41.525+05:30DNS INTERVIEW QUESTIONS ANSWERS
DNS INTERVIEW QUESTIONS ANSWERS
DNS stand for Domain Name System.
## What is the main purpose of a DNS server?
DNS servers are used to resolve FQDN hostnames into IP addresses and vice versa.
## What is the port no of dns ?
53.
## What is a Forward Lookup?
Resolving Host Names to IP Addresses.
## What is Reverse Lookup?
It?s a file contains host names to IP mapping information.
## What Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-17381570981186733482019-12-05T09:52:00.000+05:302019-12-05T09:52:58.277+05:30How to Enable timestamp for History Command
Here is a way of how you can see a timestamp for executed command when using "history" command in Linux.
You can export HISTTIMEFORMAT variable, with appropriate date formatting.
For example you can use: (update in /etc/bashrc or /etc/profile )
export HISTTIMEFORMAT='%F %H:%M:%S '
In this case the history command will give you an output like this:
[root@amitmaheshwari.in Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-56006471865613205162019-12-05T09:51:00.000+05:302019-12-05T09:51:07.186+05:30What is the status code 403 404 represented in apache server
Linux Interview Questions: - What is the status code 403,404 represented in
apache server?
403 represent forbidden error, means if a file misses some selinux security context.
404 represent that there is a cgi script missing or web pages missing.
Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-91343243157990249202019-12-05T09:47:00.001+05:302019-12-05T09:47:53.215+05:30How to Change themes and logo in zimbra ZCS8
How to Change themes and logo in zimbra ZCS8
You can change the Login and App banner images on a per domain basis in ZCS8. From the command line:
[ zimbra@amitmaheswhari.in] $ zmprov md example.com zimbraSkinLogoURL https://mail.example.com/
[ zimbra@amitmaheswhari.in] $ zmprov md example.com zimbraSkinLogoLoginBanner https://mail.example.com/img/MyLoginBanner.png
[ zimbra@amitmaheswhari.in] Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-7489758082357823742019-12-05T09:47:00.000+05:302019-12-05T09:47:13.579+05:30How to Change Admin Console URL in Zimbra
Zimbra Collaboration Suit (ZCS)
If you want to change Admin Console URL link showed in the webmail of administrator.
For example if it shows :
https://mail.example.com:7071
Now I want to change this admin URL to https://example.com:7071
[zimbra@amitmaheshwari.in ] $ zmprov md example.com zimbraWebClientAdminReference https://example.com:7071/
Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-62389422820961719342019-12-05T09:45:00.000+05:302019-12-05T09:45:42.012+05:30How to Find Biggest Files in Linux
Easiest way to find biggest files and folder/Directory in LINUX by Simple command (ls and du )
A common problem with computers is when you have a number of large files (such as audio/video clips) that you may want to get rid of. You can find the biggest files in the current directory with:
Execute bellow command in desired Folder or Path.
[root@amitmaheshwari.in]# ls -lSrh
The "Unknownnoreply@blogger.comtag:blogger.com,1999:blog-5236351575215231548.post-30853950569371392692019-12-05T09:44:00.000+05:302019-12-05T09:44:55.851+05:30 How to identify HTML5
HTML5 is the next version of HTML standards. HTML5 adds many new features for web developers that use to require plug-ins (flash) or javascript.
To check if a website is in HTML5 all you have to do is check the source code:
Right click on a page
Select "View Source Code" or "View Page Code"
The first line will have the DOCTYPE which shows the HTML version of the page.&Unknownnoreply@blogger.com