2017-01-27 09:17 pm

Installing Kernel-based Virtual Machine (KVM) on Ubuntu 16.04 server

Kernel-based Virtual Machine (KVM) is a virtualization infrastructure for the Linux kernel that turns it into a hypervisor. It was merged into the Linux kernel mainline in kernel. It is now part of Linux kernel itself. It consists of a loadable kernel module, kvm.ko, that provides the core virtualization infrastructure and a processor specific module, kvm-intel.ko Intel or kvm-amd.ko for AMD cpu.

=> Read more: How to install KVM on Ubuntu 16.04 LTS Headless Server
2017-01-27 09:15 pm

Installing MariaDB Server in a FreeBSD 11

MySQL is a very fast, multi-threaded, multi-user and robust SQL database server. The latest version is located at /usr/ports/databases/mysql57-server/. MariaDB is a database server that offers drop-in replacement functionality for MySQL1. MariaDB is built by some of the original authors of MySQL, with assistance from the broader community of Free and open source software developers around the world. In addition to the core functionality of MySQL, MariaDB offers a rich set of feature enhancements including alternate storage engines, server optimizations, and patches. The latest version is located at /usr/ports/databases/mariadb55-server/. In this tutorial, you will learn how to install MariaDB server and create a databases, users, and grant sql rights using sql commands on a FreeBSD 10 or 11 server.

=> More info: How To Install MariaDB Databases on a FreeBSD v10/11 Unix Server
2017-01-27 04:51 pm

How to ppen a file in a tab in vim in readonly mode on Linux, MacOS and Unix system

Want to open a file in read-only mode on Unix, try:
vim -M file
OR open a tab in read-only mode:
: view file

More info: Open a file or a tab in vim in readonly mode
2017-01-26 04:20 pm


If you are getting this error then you probably reset the permissions on your keys:

chmod 0400 ~/.ssh/key
chmod 0700 ~/.ssh/
ssh -i ~/.ssh/key user@server

More info: Fixing ssh error.
2017-01-24 07:36 pm

Want to flush the content of memcached server using bash on Linux/Unix?

You type the following command to flush the content of memcached server:
echo flush_all >/dev/tcp/

=> More commands and options here about the same.
2017-01-24 05:02 pm
Entry tags:

curl ignore invalid ssl certificate warning

Want to ignore SSL warning with curl command on Linux/Unix/MacOS? Try:

curl -k url
curl -k -I url

More info: cURL Ignore SSL Certificate Warnings
2017-01-24 03:22 pm

{HOWTO} Limiting SSH Connections with ufw on Linux

How do I limit ssh connection attempts using UFW (Uncomplicated Firewall) on Ubuntu or Debian Linux server?

UFW means Uncomplicated Firewall. It defaults on Ubuntu and can be installed on other Linux distros such as Arch Linux, Debian and more.

Read more here...
2017-01-24 02:09 am

Achieving 100,000,000 database inserts per second using Apache Accumulo and D4M

The Apache Accumulo database is an open source relaxed consistency database that is widely used for government applications. Accumulo is designed to deliver high performance on unstructured data such as graphs of network data. This paper tests the performance of Accumulo using data from the Graph500 benchmark. The Dynamic Distributed Dimensional Data Model (D4M) software is used to implement the benchmark on a 216-node cluster running the MIT SuperCloud software stack. A peak performance of over 100,000,000 database inserts per second was achieved which is 100x larger than the highest previously published value for any other database. The performance scales linearly with the number of ingest clients,
number of database servers, and data size. The performance was achieved by adapting several supercomputing techniques to this application: distributed arrays, domain decomposition, adaptive load balancing, and single-program-multiple-data programming.

Read More info here {PDF version}
2017-01-24 02:08 am

What does it take to be a good Python/Perl/Ruby/Java/C/C++ programmer?

I’ve been writing code now for almost 10 years, I’ve worked on different projects in size, with different teams (some solo projects) on various platforms. Although I still feel I have a lot to learn and I do suffer from an impostor syndrome, I think I’ve learned a few things.

I had a discussion recently with a fellow developer on what does it mean to be a good programmer, and what is “good code”.

More here.
2017-01-23 11:50 pm

How to install LXD container under Linode KVM Cloud server

For security and ease of admin, I want to install LXD on my cloud server either powered by XEN or KVM. How do I install LXD on Ubuntu Linux server powered by KVM virtualization technology?

In this quick tutorial you will learn how to install the latest stable version of LXD container under KVM cloud server hosted at Linode for security mechanism on Ubuntu Linux 16.04.xx LTS server.
2017-01-23 11:26 pm

The Awk Programming Language for all {PDF version}

AWK is a programming language designed for text processing and typically used for a data extraction and reporting tool. It is a standard feature of Linux, FreeBSD, OpenBSD, MacOS and most Unix-like systems.

Download: The AWK programming book (PDF version)
2017-01-23 05:26 pm

Directly attach screen/tmux over ssh session & save a useless parent bash process:

Run the following command:

ssh -t box screen -r
ssh -t box tmux a
ssh -t user@server screen -r
ssh -t user@server tmux a

2017-01-23 05:26 pm

How To Create a Sudo User on Ubuntu Linux 16.04 LTS Server Hosted in Cloud

I am a new Ubuntu Linux 16.04.xx LTS server user. How do I create a new sudo user on my server? How do I add a new user as sudoer file using the command line option on Ubuntu?

In Linux (and Unix in general), there is a SuperUser named root. The root user can do anything and everything, and thus doing daily work as the root can be very dangerous. You could type a command incorrectly and destroy the system.

Read more here: How To Create a Sudo User on Ubuntu Server
2017-01-23 04:12 pm
Entry tags:

How to determine if a bash variable is empty in a Linux or Unix?

My shell script depends upon user input. How do I find out if a variable called $_JAIL path is empty under a Linux / Apple OS X / Unix like operating systems? What is the best way to determine if a variable in bash is empty?

Pass the -z option to the if command or conditional expression.

Read more here