Solved : Check without telnet if port is open on remote host – Linux

Earlier many system admins were using telnet to check if a port is open on remote machine. But, because of security concerns telnet is now not recommended to be installed on most linux boxes.

But hey we still need to check the remote port. This is part of normal troubleshooting in a linux admin’s life.

So, instead of using telnet you can use  nc.  netcat or nc is a  simple tool which is generally installed by default in linux distributions or you can install it with instructions below.

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Real shell scripting interview questions

Q What is Shell?

Ans: Shell is a command interpreter, which interprets the command which the user gives to the kernel. It can also be defined as an interface between a user and operating system.

Q How to debug the problems encountered in shell script/program?

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Must have skills for DevOps Engineer and Free methods to learn them

Many people have asked us how to become a DevOps engineer so in this post we will show you the skills and technologies which can get you there.

Before we start we should know what is “DevOps”. As you can see the word is combination of “Developer” and “Operations”. So a DevOps engineer is suppose to be a bridge between the development and operations processes.

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Let’s see which skills do you need to become a DevOps engineer. In this post we will also discuss how you can acquire these skills for free. We have also mentioned some advanced paid courses which can help you acquire these skills quickly.

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Solved: How to start or stop Jenkins in Linux and check it’s port number

In this post we will see how to start or stop Jenkins on different Linux distributions. Also we will see how to check the status of Jenkins service and identify the port on which it is running or listening.

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Solved: Create virtual environment with python 3 in linux

Once you have installed python 3.6 as described in the last post you can create virtual environment to work with it.

  • First let’s install the package of virtual environment for python 3.

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Solved: Install Python 3 in Linux and set it as default

In this post we will show you how to install python 3 in a Linux box. We have Centos 7 installed in our server.

Check installed python version

Most of the Linux versions by default have python installed. So let’s check the current version.

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[ec2-user@cloudvedas ~]$ python --version
 Python 2.7.5
[ec2-user@cloudvedas ~]$

As we can see from the above output, currently we have Python 2 installed and we need Python 3 so let’s install it.

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Solved: How to extend or grow a linux filesystem under LVM

In this post we will see how to grow a Linux filesystem without reboot.

  • Let’s check our current filesystem. We want to extend this filesystem by 200MB.
[root@cloudvedas CVFS1]# df -h /CVFS1
Filesystem                  Size Used Avail Use% Mounted on
/dev/mapper/cvsvg-cldvdsvol1 47M 12M    32M  26%   /CVFS1
[root@cloudvedas CVFS1]#
  • First check if we have free space in VG

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Solved: How to label a disk in Linux

In this post we will see how to label a new disk in Linux and create a new LVM partition.

Step 1 Scan the new LUNS.

Step 2 List the available disks and identify the one you want to use.

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  fdisk -l |grep /dev/ |grep -v dm

Step 3 Use fdisk to label the disk. Here we are using disk sdb .

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LVM Crash course

In this post we will give you a crash course on Linux LVM (Logical Volume Manager). This post will cover the most used LVM commands in a Linux Admin life.

Before we start first let’s go through the concepts.

Physical Volumes (PVs): Storage devices (physical hard disks, partitions, RAID arrays etc.) provides raw storage
Volume Groups (VGs): Combine multiple PVs to create a group. They can be mirror or concatenation of PVs.
Logical Volumes (LVs): Create smaller volumes from the Volume Group(VG) as per your size requirement. You can can use the LVs to create filesystem on them.

Below commands are for RHEL 7.

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All the below commands will require root access. You can either run them with sudo  or switch to root user as mentioned below.

sudo su -

Install LVM

[root@cloudvedas ~]# yum install lvm2*

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Solved: How to schedule a cron job in Linux or Solaris

In this post we will see what’s a cron job and how we can set it.

Cron is managed by a crontab file. Its a configuration file in which we can schedule shell command to run periodically.

Scheduling cron

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