Selasa, 18 Juni 2019

Install and Configure KVM on Ubuntu 18.04

We can use VirtualBox or KVM on Ubuntu to do virtualization, we often use virtual machine for development, not necessarily on a server, we can use KVM on Ubuntu Desktop.

To setup KVM on Ubuntu 18.04, perform the following steps:

$ sudo apt update
$ sudo apt upgrade
$ sudo apt install qemu qemu-kvm libvirt-bin  bridge-utils  virt-manager

What the command does:

1. Update and upgrade Ubuntu
2. Install required packages for running KVM
3. We use qemu and qemu-kvm for hypervisor
4. bridge-utils for working with network bridge
5. virt-manager is GUI application for KVM.

Let see our new network interface created by bridge-utils and KVM by running "ip a" command:

4: virbr0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc noqueue state UP group default qlen 1000
    link/ether 52:54:00:2f:e6:3c brd ff:ff:ff:ff:ff:ff
    inet 192.168.122.1/24 brd 192.168.122.255 scope global virbr0
       valid_lft forever preferred_lft forever
5: virbr0-nic: <BROADCAST,MULTICAST> mtu 1500 qdisc fq_codel master virbr0 state DOWN group default qlen 1000
    link/ether 52:54:00:2f:e6:3c brd ff:ff:ff:ff:ff:ff

Now, there are two new network interfaces, those are bridge network interface created by libvirt, we can use virbr0 for bridge network with our virtual machine.

Lets run a virtual machine for testing, we will use CentOS minimal as a guest OS, before that, download CentOS minimal image, and put it where ever you want, and the run the following command:

$ virt-install --virt-type=kvm --name centos7 --ram 2000 --vcpus=2 --os-variant=centos7.0 --network=bridge=virbr0,model=virtio --graphics vnc  --cdrom=/var/lib/libvirt/images/CentOS-7-x86_64-Minimal-1810.iso --disk path=/var/lib/libvirt/images/centos.qcow2,size=10,bus=virtio,format=qcow2

We create a virtual machine, with 2GB ram, and 2 cpus, using CentOS 7 as a guest OS, and we create 10GB virtual disk.

That's all.

Nested Virtualization KVM on CentOS 7

Nested Virtualization is disabled by default on CentOS 7, we can verify by running a command:

# cat /sys/module/kvm_intel/parameters/nested

Make sure KVM is intalled on the machine, if output is N, then Nested Virtualization is disabled, to enable the feature, set options kvm-intel nested=1 in /etc/modprobe.d/kvm-nested.conf

# echo "options kvm-intel nested=1" > /etc/modprobe.d/kvm-nested.conf

Reboot the machine, and verify like above command.

Selasa, 26 Maret 2019

Delete All Comments in a File With VS Code

What if you want to delete all comments in a file with VS Code? VS Code has a find and replace feature that support regular expression, so we can use that feature to automatically find line starting with hash (#), Here we go: 1. Press ctrl + f 2. Click on "Use regular expression" button on "find and replace" widget 3. Type the regular expression: ^#.*$\n 4. Leave the "Replace" field empty 5. Click "Replace All" button And all of your comment deleted, actually it is replaced by the empty character. Notes ^#.*$\n : • ^ = matches position just before the first character of the string • # = character that we want to find • . = matches a single character. Does not matter what character it is, except newline • * = matches preceding match zero or more times • $ = matches position just after the last character of the string • \n = Line feed character

7 GNU Screen Commands To Make Your Life Easier

Here 7 GNU Screen commands that could make your life easier:

* ^A ^W - window list
* ^A ^C - create new window
* ^A space - next window
* ^A p - previous window
* ^A ^A - switch to previous screen
* ^A [0-9] - go to window [0-9]
* ^A esc - copy mode

Minggu, 02 Desember 2018

Futsal dan Jogging

Futsal dan Jogging, saya suka dua olah raga ini, karena setiap kali setelah futsal atau jogging seluruh badan saya terasa pegel-pegel, merata dari kepala hingga kaki.

Untuk olah raga yang lain, terutama yang pegelnya di bagian tertentu, saya tidak begitu suka.

Ya, sesederhana itu alasannya :D

Jumat, 26 Mei 2017

Matplotlib show or imshow not working

When using matplotlib inside terminal console, and execute show or imshow, if we want to see the plot then we need to activate interactive mode:

matplotlib.pyplot.ion()


To turn off interactive mode:


matplotlib.pyplot.ioff()


Interactive mode causing program run slower, so just activate when needed.

Kamis, 08 Januari 2015

Beberapa Aplikasi Pendidikan di Linux

Berikut ini beberapa contoh aplikasi pendidikan di Linux :

  • GCompris
Aplikagi GCompris cocok untuk mengenalkan komputer kepada anak-anak, belajar mengenal papantik dan tetikus, mengenal perhitungan, dan masih banyak hal menarik lainnya.


  • Tux Typing

Tux Typing memiliki fitur-fitur yang dibutuhkan untuk belajar mengetik.


  • Tuxmath

Untuk belajar matematika agar suasana belajar menjadi menyenangkan, bisa menggunakan Tuxmath


  • KGeography

Untuk mengenalkan negara-negara tetangga, bisa menggunakan aplikasi KGeography


  • KWordquiz

Belajar bahasa bisa menggunakan KWordquiz


  • KBruch

Untuk belajar Matematika lebih lanjut, bisa menggunakan aplikasi KBruch

Contoh di atas merupakan sebagian kecil dari sekian banyak aplikasi-aplikasi dengan kode sumber terbuka yang bisa berjalan di Linux, contoh yang lain adalah : Carmetal, Dr Geo, Geo Gebra, Kalgebra, Stellarium, Stardict, Kalzium, dan masih banyak lagi.