Zabbix is very popular, easy to use, fast monitoring tool. It support monitoring Linux, Unix, windows environments with agents, SNMP v1,v2c,c3, agentless remote monitoring. It can also monitor remote environment with a proxy without opening port for remote environments. You can send email, sms, IM message, run sny type of script to automate daily or emergency tasks based on any scenario.

Zabbix 4 is the latest version. New version supports php7, mysql 8, encryption between host and clients, new graphical layout, trend analysis and many more. With zabbix you can use zabbix_sender and zabbix_get tools to send any type of data to zabbix system and trigger alarm for any value. With these capabilities Zabbix is programmable and your monitoring is limited to your creativity and capability.

Installing from Zabbix repository is the easiest way. In order to setup from source file you need to setup compilers and make decisions about which directories and features get used for your environment. The Zabbix repository files provide all features enable and ready to go environment for your needs.

If you had the chance to use the setup we have select xfce for desktop environment. If you have not rest of the installation steps will perfectly work even if you had minimal setup environment which is the cleanest environment you find for Debian.

Security First!

Login to the root user and add the guest user to soders file simple adding.

Username ALL=(ALL:ALL) ALL

Into the configuration file /etc/sudoers

You can also use

To directly edit the file with the default text editor (nano in my case)

Install Mysql

Once you create the guest user and give root privileges we can login to the user with

and start to add sudo in front of the commands to send root commands with control.

Install Mysql with following command

$ sudo apt-get install mysql-server

Press ‘Y’ in order to download and install.

Right after the installation add mysql to the startup sequence so when system reboots your mysql server will be up.

$ sudo systemctl enable mariadb

$ sudo systemctl start mariadb

You can test if mysql is up with the following command

You should be able to login to the database server without entering a password.

Type quit to log out of the server

Install Zabbix from Repository

Once the database server installation has finished we can start installing zabbix application.

Download apt repo package to the system

$sudo wget https://repo.zabbix.com/zabbix/4.0/debian/pool/main/z/zabbix-release/zabbix-release_4.0-2+stretch_all.deb

$ sudo dpkg -i zabbix-release_4.0-2+stretch_all.deb

$sudo apt update

Lets install Zabbix server and front end packages.

$ sudo apt install zabbix-server-mysql zabbix-frontend-php zabbix-agent

Add Zabbix Services to Startup

Once all packages are installed enable Zabbix services but don’t start yet. We need modifications on the configuration file.

$ sudo systemctl enable apache2

$ sudo systemctl enable zabbix-server

$ sudo systemctl enable zabbix-agent

Create Database and Deploy Zabbix Database Tables

Now it is time to create database for Zabbix. Please note you can create a database with any name and a user. All you need is replace apropirate value with the commands we provided below.

In our case we will pickup (all are case sensitive)

We create zabbix database and user with mysql root user

After creating database and users we create the Zabbix database tables in our new database with the following command

# zcat /usr/share/doc/zabbix-server-mysql*/create.sql.gz | mysql -uzabbix -p -B Zabbix

Enter your database password in next step

Process may take about 1-10 minutes depending on your performance of server.

Configure Zabbix Server

In order to have our Zabbix server start and get ready for business we must define database parameters into the zabbix_server.conf

$ sudo nano /etc/zabbix/zabbix_server.conf

DBHost=localhost
DBUser=zabbix
DBPassword=VerySecretPassword
DBName=zabbix

Time zone needs to be entered into /etc/zabbix/apache.conf file in order not to face any time related inconsistency in our environment. Also this step is a must for a errorless environment. If this parameter is not set Zabbix web interface will warn us every time. In my case the time zone is Europe/Istanbul.

You can get full list of PHP time zones here.

Please also note there are php7 and php5 segments here. In our setup php 7 was installed so modifying the php_value date.timezone in the php7.c segment was enough but we recommend modifying the php5 for compatibility issues.

Save the file.

Now stop and start services in order to have all changes in affect.

$ sudo systemctl restart apache2 zabbix-server zabbix-agent

Setting up Web Server

Now database and Zabbix services are up. In order to check whats going in our systems we should setup web interface with mysql support. This is our last step before going online and start checking some stats.

Welcome Screen.

Check if everything in ok with Green color.

Define user name and password we defined in setting up database section.

DBHost=localhost
DBUser=zabbix
DBPassword=VerySecretPassword
DBName=zabbix

You can define Zabbix-server name in this step. You want to have it called something like watch tower or monitoring server something like it too.

Note: You can change this setting from

/etc/zabbix/web/zabbix.conf.php

You can change the $ZBX_SERVER_NAME parameter in the file.

Verify setting and press Next Step

Default username and password are (case sensitive)

Now you can check your system stats.

Go to Monitoring -> Latest data

And select Zabbix Server from Host groups and check if stats are coming live.

Conclusion

We have setup the database server in the beginning because a system with already installed packages can prevent any version or mysql version we want to download because of conflicts. You can also download mysql server from the mysql.com site.

Later on we continued with Zabbix binary package installation and created database and user. Next step was to configure Zabbix configuration files and install web interface. In later stages you can install SSL, modify configuration for a specific web domain, proxy through nginx or directly run from nginx with php-fpm, upgrade PHP and such things like things. You may also disable Zabbix-agent in order to save from database space. It is all up to you.

Now you can enjoy monitoring with Zabbix. Have a Nice Day.

Source

Btrfs or B-tree file system is the newest competitor against OpenZFS, arguably the most resilient file system out there. Both the file systems share some commonalities such as having checksum on data blocks, transaction groups and copy-on-write mechanism, making them both target the user groups. So what’s the difference and which one should you use?

1. Copy-on-Write (COW) Mechanism

Both the file systems use copy-on-write mechanism. This means that, if you are trying to modify a file, neither of the file systems will try to overwrite the existing data on the disk with the newer data. Instead, the newer data is written elsewhere and once the write operation is complete, the file system simply points to the newer data blocks and the old blocks get recycled over time. This mechanism allows both the file systems to have features like snapshots and cloning.

COW also prevents edge cases like partial writes,which can happen due to kernel panic or power failure and potentially corrupt your entire entire file system. With COW in place, a write has either happened or not happened, there’s no in between.

2. Pooling and RAID

Both the file systems intend on eliminating the need of a volume manager, raid and other abstractions that sit between the file system and the disks. This is more robust and reliable than having a hardware RAID controller, simply because it eliminates a single point of failure — The RAID controller itself.

OpenZFS offers a stable, reliable and user-friendly RAID mechanism. You can mirror between drives, use RAIDZ1 which spreads your data across 3 or more disk with one parity block. So it can withstand upton 1 disk’s failure per Vdev. Similarly, RAIDZ2 can use 4 or more disks and withstand upto 2 disks failing and similarly we have RAIDZ3.

Btrfs too has these features implemented, the difference is simply that it calls them RAID, instead of RAIDZ and so on. Some more complicated RAID array setups like RAID56 are buggy and not fit for use, at the time of this writing.

3. Licensing

One of the reasons OpenZFS came so late on the GNU/Linux ecosystem is because of its license incompatibility with GNU GPL. Without getting into too much details, Btrfs is under GPL which allows users to take source code and modify it, but the modifications should also be published under GPL and stay open source.

OpenZFS on the other hand, is licensed under CDDL which is much more permissive and allows users to modify and distribute code with a greater degree of freedom.

4. Communities and Companies Behind Them

OpenZFS has a massive community behind it. FreeBSD community, Illumos community and many other open source projects rely on OpenZFS and thus contribute back to the file system. It has grown several fold in terms of code base, user base, features and flexibility ever since its inception. Companies like Delphix, iXsystems, Joyent and many more rely on it and have their developers work on because it is a core component of their business. Many more organizations might be using OpenZFS without our knowledge, thanks to the CDDL license, they don’t have to come forth and say out-right that they use it.

Btrfs had Red Hat as one of the main steward of its community. However, that recieved a major blow a while back when Red Hat deprecated the filesystem this means you won’t be seeing it in any future RHEL and the company won’t provide commercial support for it out-of-the-box. SUSE, however, has gone so far as to make it their default and their is still a thriving community behind the file system with contributions from Facebook, Intel and other 800 pound gorillas of the Silicon Valley.

5. Reliability

ZFS was designed to be reliable right from the beginning. People have zpools dating back to the early 2000s that are still usable and guaranteed to not return erroneous data silently. Yes, there has been a few snafus with files disappearing on for OpenZFS on Linux but given its long history the track record has been surprising clean.

Btrfs, on the other hand, has had issues right from the beginning. With buggy interfaces to straight up data loss and file corruption. Even now, it is bit of a laughing stock in the community. Make of that what you will.

6. Supported OSes

Btrfs has had its origin has a file system for Linux while ZFS was conceived inside Sun, for Solaris OS. However, OpenZFS has long since been ported to FreeBSD, Apple’s OS X, open source derivatives of Solaris. It’s support for Linux came a little later than one would have predicted, but it is here and corporations rely on it. A project for making it run on Microsoft Windows is also making quite a bit of progress, although it is not quite there yet.

Conclusion: A Note on Monocultures

All of this talk may convince you to use OpenZFS to keep your data safe, and that is not a bad course of action. It is objectively better than Btrfs in terms of features, reliability, community and much more. However, in the long run this might not be good for the open source community, in general.

In a post titled similar to this one, the author talks about the dangerous of monocultures. I encourage you to go through this post. The gist of it is this — Options are important. One of the greatest strength of Open Source software (and software, in general)is that we have multiple options to adopt. There’s Apache and then there’s Nginx, there are BSDs and Linux, there is OpenSSL and there is LibreSSL.

If there is a fatal flaw in any of these key technologies, the world will not stop spinning. But with the prevalence of OpenZFS, the storage technology has turned into something of a monoculture. So, I would very much like for the developers and system programmers who are reading this, to adopt not OpenZFS but projects like Btrfs and HAMMER.

Source

In early 2019 we will see the first stable release of GCC 9 as the annual update to the GNU Compiler Collection that is bringing the D language front-end, more C2X and C++ additions, various microarchitecture optimizations from better Znver1 support to Icelake, and a range of other additions we’ll provide a convenient recap of shortly. But for those wondering how the GCC 9 performance is looking, here are some fresh benchmarks when benchmarking the latest daily GCC 9.0 compiler against GCC 7.4 and GCC 8.2 atop Clear Linux using an Intel Core i9 7980XE Skylake-X system.

 

 

Similar to the few other tests we’ve done at different times throughout the years and on different hardware, this article is a last look as we end out 2018 to see how the GCC9 performance is looking on Intel x86_64 compared to the past two major releases. When the formal GCC 9.1.0 compiler release nears its debut around the end of Q1-2019, I’ll be back with plenty more compiler benchmarks on different CPUs. Of course, there will also be benchmarks of the upcoming LLVM Clang 8.0 release that should be out roughly around the same time as GCC9 stable.

 

All of this testing was done when building GCC 7.4 / 8.2 / 9.0 from source on Clear Linux and the compiler releases configured using “–disable-multilib –enable-checking=release” and keeping the CFLAGS/CXXFLAGS the same throughout building all of the open-source benchmarks used for evaluating the performance of the resulting binaries. Going back further than GCC 7 was not possible on this system due to Glibc issues. The Phoronix Test Suite was used for automating this process, as always.

 

Source

Port scanning is a process to check open ports of a PC or a Server. Port scanners are often used by gamers and hackers to check for available ports and to fingerprint services. There are two types of ports to scan for in TCP/IP Internet Protocol, TCP(Transmission Control Protocol) and UDP(User Datagram Protocol). Both TCP and UDP have their own way of scanning. In this article, we’ll look at how to do port scan in Linux environment but first we’ll take a look at how port scanning works. Note that port scanning is illegal in often countries, make sure to check for permissions before scanning your target.

TCP Scanning

TCP is stateful protocol because it maintains the state of connections. TCP connection involves a three-way handshaking of Server socket and client-side socket. While a server-socket is listening, the client sends a SYN and then Server responds back with SYN-ACK. Client then, sends ACK to complete the handshake for the connection

To scan for a TCP open port, a scanner sends a SYN packet to the server. If SYN-ACK is sent back, then the port is open. And if server doesn’t complete the handshake and responds with an RST then the port is closed.

UDP Scanning

UDP on the other hand, is a stateless protocol and doesn’t maintain the state of connection. It also doesn’t involve three-way handshake.

To scan for a UDP port, a UDP scanner sends a UDP packet to the port. If that port is closed, an ICMP packet is generated and sent back to the origin. If this doesn’t happen, that means port is open.

UDP port scanning is often unreliable because ICMP packets are dropped by firewalls, generating false positives for port scanners.

Port Scanners

Now that we’ve looked at how port scanning works, we can move forward to different port scanners and their functionality.

Nmap

Nmap is the most versatile and comprehensive port scanner available till now. It can do everything from port scanning to fingerprinting Operating systems and vulnerability scanning. Nmap has both CLI and GUI interfaces, the GUI is called Zenmap. It has a lot of varying options to do quick and effective scans. Here’s how to install Nmap in Linux.

sudo apt-get update
sudo apt-get upgrade -y
sudo apt-get install nmap -y

Now we’ll use Nmap to scan a server (hackme.org) for open ports and to list services available on those ports, its really easy. Just type nmap and the server address.

To scan for UDP ports, include -sU option with sudo because it requires root privileges.

There are a lot of other options available in Nmap such as:

-p- : Scan for all 65535 ports
-sT : TCP connect scan
-O : Scans for operating system running
-v : Verbose scan
-A : Aggressive scan, scans for everything
-T[1-5] : To set the scanning speed
-Pn : In case the server blocks ping

Zenmap

Zenmap is a GUI interface of Nmap for click-kiddies so that you won’t have to remember its commands. To install it, type

sudo apt-get install -y zenmap

To scan a server, just type its address and select from available scan options.

Netcat

Netcat is a raw TCP and UDP port writer which can also be used as a port scanner. It uses connect scan that’s why it is not so fast like Network Mapper. To install it, type

ubuntu@ubuntu:~$ sudo apt install netcat-traditional -y

To check for an open port, write

ubuntu@ubuntu:~$ nc -z -v hackme.org 80
…snip…
hackme.org [217.78.1.155] 80 (http) open

To scan for a range of ports, type

ubuntu@ubuntu:~$ nc -z -nv 127.0.0.1 20-80
(UNKNOWN) [127.0.0.1] 80 (http) open
(UNKNOWN) [127.0.0.1] 22 (ssh) open

Unicornscan

Unicornscan is a comprehensive and fast port scanner, built for vulnerability researchers. Unlike Network Mapper, it uses its own User-land Distributed TCP/IP stack. It has a lot of features that Nmap doesn’t, some of them are given,

• Asynchronous stateless TCP scanning with all variations of TCP Flags.
• Asynchronous stateless TCP banner grabbing
• Asynchronous protocol specific UDP Scanning (sending enough of a signature to elicit a response).
• Active and Passive remote OS, application, and component identification by analyzing responses.
• PCAP file logging and filtering
• Relational database output
• Custom module support
• Customized data-set views

To install Unicornscan, type

ubuntu@ubuntu:~$ sudo apt-get install unicornscan -y

To run a scan, write

ubuntu@ubuntu:~$ sudo us 127.0.0.1
TCP open ftp[ 21] from 127.0.0.1 ttl 128
TCP open smtp[ 25] from 127.0.0.1 ttl 128
TCP open http[ 80] from 127.0.0.1 ttl 128
…snip…

Conclusion

Ports scanners come in handy whether you are a DevOp, Gamer or a Hacker. There is no real comparison between these scanners, none of them is perfect, each of them has its benefits and drawbacks. It completely depends upon your requirements and how you use them.

Source

Source

On Christmas Eve marked the long-awaited release of the OpenMandriva Lx 4.0 Alpha and with that new version of the Mandrake/Mandriva-derived operating system came an AMD Zen “Znver1” optimized Linux build. Of course that caught my interest and I was quickly downloading this first Linux distribution with an AMD Ryzen/EPYC optimized binaries to see how it compares to its generic x86_64 operating system installation.

The AMD Zen optimized version of OpenMandriva Lx 4.0 caters its compiler flags to these latest AMD processors and other tuning to try to improve the experience. (There are some more details on the design changes with their Znver1 build in our forums.) This AMD Zen optimized build not only has the stock OS image rebuilt for Zen but a copy of its entire package archive re-built with Zen optimizations as an alternative to their generic Intel/AMD x86_64 package repository. It perhaps would be interesting if they pursued Function Multi-Versioning (FMV) and other compiler techniques for optimizations moving forward. But for users, simply download and install the OpenMandriva Znver1 image and if you are off to the races with AMD Zen optimizations by default.

The concept of an optimized Linux OS build catered towards a particular CPU microarchitecture is not new, but the first time we are seeing a major Linux distribution offer such for AMD Zen. On the Intel side the most prominent example is Intel’s own Clear Linux platform out of their Open-Source Technology Center. With Clear Linux they take performance to the extreme of just not catering the CFLAGS/CXXFLAGS and other basic tunables towards recent Intel microarchitectures but with their engineering resources they have also worked on various patches to the Linux kernel, Glibc, GCC, and other key open-source components. The Intel OTC work also ends up landing back upstream in the respective projects but for finding the leading Intel Linux performance is generally first found on Clear Linux. In our comparisons where putting Clear Linux up against a variety of other major Linux distributions, it can usually beat out the competition at least 60% of the time in multi-way Linux OS comparisons when running on recent Intel hardware but even its performance on AMD hardware tends to pack quite a punch too. Thus with seeing the OpenMandriva Lx 4.0 Alpha 1 having a Znver1 build made me quite anxious to run some Christmas day benchmarks.

OpenMandriva Lx 4.0 Alpha 1 has the Linux 4.18 kernel, KDE Plasma 5.14.4, X.Org Server 1.20.3, Mesa 18.3.1 and EXT4 by default. But not all of the OpenMandriva Lx 4.0 tunables are in the name of performance as for example on both Alpha 1 builds they are defaulting to the CPUFreq conservative governor, which tends to be slower than the likes of CPUFreq performance or even ondemand.

 

For this initial OpenMandriva Lx 4.0 benchmarking, an AMD Ryzen Threadripper 2950X system was used for this testing powered by the Phoronix Test Suite.

Source

VirtualBox is a free virtualization solution from Oracle. VirtualBox can virtualize Windows XP, Windows Vista, Windows 7, Windows 10, Ubuntu, Debian, CentOS and many other versions of Linux, Solaris, some BSD variants etc. Recently, VirtualBox 6.0, a major update of VirtualBox came out. In this article, I will show you how to install VirtualBox 6.0 on Ubuntu 18.04 LTS. This article mainly focuses on Ubuntu 18.04 LTS, but this article will also work for Ubuntu 16.04 LTS and later. So, let’s get started.

Enable Hardware Virtualization:

Before you install VirtualBox 6.0, make sure hardware virtualization is enabled. If you’re using an Intel processor, then you have to enable VT-x or VT-d from the BIOS of your computer. If you’re using a AMD processor, then you have to enable AMD-v from the BIOS of your computer. This is very important. Without hardware virtualization enabled, your virtual machines will perform very badly.

Adding VirtualBox Package Repository:

VirtualBox 6.0 is not available in the official package repository of Ubuntu 18.04 LTS. But we can easily add the package repository of VirtualBox on Ubuntu 18.04 LTS and install VirtualBox 6.0 from there. To add the official package repository of VirtualBox, run the following command:

$ echo “deb https://download.virtualbox.org/virtualbox/debian $(lsb_release -cs) contrib” | sudo tee /etc/apt/sources.list.d/virtualbox.list

Now, type in your login password and press <Enter>.

The official package repository of VirtualBox should be added.

Adding VirtualBox Public PGP Key:

Now, you have to add the public PGP key of VirtualBox official package repository to APT. Otherwise, you won’t be able to use the VirtualBox official package repository. To add the public PGP key of the official package repository of VirtualBox, run the following command:

$ wget -q https://www.virtualbox.org/download/oracle_vbox_2016.asc -O- | sudo apt-key add –

The public PGP Key should be added.

Installing VirtualBox 6.0:

Now that the official VirtualBox package repository is ready to use, we can install VirtualBox 6.0. First, update the APT package repository cache with the following command:

The APT package repository should be updated.

Now, install VirtualBox 6.0 with the following command:

$ sudo apt install virtualbox-6.0

Now, press y and then press <Enter> to continue.

The required packages are being downloaded.

VirtualBox 6.0 should be installed.

Running VirtualBox 6.0:

Now, you should be able to run VirtualBox 6.0 from the Application Menu as you can see in the screenshot below.

VirtualBox 6.0 dashboard.

As you can see, I am currently running VirtualBox 6.0.0. Note the VirtualBox version because you will need it when you will install VirtualBox Extension Pack.

Installing VirtualBox Extension Pack:

VirtualBox Extension Pack enables support for USB 2.0 and USB 3.0 devices, RDP, disk encryption, NVMe and PXE boot for intel cards and many more. It is a must have tool for any VirtualBox user.

You have to download VirtualBox extension pack from the official website of VirtualBox and install it yourself in order to use these extra features in VirtualBox. First, to visit the official FTP directory of VirtualBox at https://download.virtualbox.org/virtualbox/6.0.0

Once the page loads, click on the “Oracle_VM_VirtualBox_Extension_Pack-6.0.0.vbox-extpack” file as marked in the screenshot below.

NOTE: Here, 6.0.0 is the version of the VirtualBox you installed. If it’s different for you, then replace 6.0.0 in the URL with the version you have.

Your browser should prompt you to save the file. Select Save File and click on OK.

Your download should start.

Once the download is complete, start VirtualBox 6.0 and go to File > Preferences…

Now, go to the Extensions tab.

From the Extensions tab, click on the add icon as marked in the screenshot below.

A file picker should be opened. Now, select the VirtualBox Extension Pack file you just downloaded and click on Open.

Now, click on Install.

Now, you have to accept the VirtualBox License. To do that, scroll down and click on I Agree.

You need super user privileges in order to install VirtualBox Extension Pack. Type in the password for your login user and click on Authenticate.

VirtualBox Extension Pack should be installed.

Finally, click on OK.

Now, you can start using VirtualBox 6.0 to create and run virtual machines of your favorite operating systems. So, that’s how you install VirtualBox 6.0 on Ubuntu 18.04 LTS. Thanks for reading this article.

Source

How to install Django on Ubuntu 18.04

Install Django on Ubuntu 18.04

Django is the most popular web framework which is designed to develop fully featured Python Web Applications. By using Django you can build secure, scalable and maintainable dynamic web applications. In this tutorial, you are going to install Django on Ubuntu 18.04 using Python Virtual Environment. The best thing to use Python Virtual Environment is you can create multiple Django Environments on a single computer without affecting other Django projects. It also will become easier to install a specific module for each project.

Prerequisites

Before you start to install Django on Ubuntu 18.04. You must have the non-root user account on your system with sudo privileges.

Install tree command to use it in further tutorial for better understanding.

sudo apt install tree

Confirm Python Installation and Install venv

Python 3.6 is by default installed on Ubuntu 18.04. Confirm the Python installation and check the Python version by typing following command.

python3 -V

Output should be as give below. Note version number may vary.

Output:
Python 3.6.7

By using venv module we can create virtual environments in Python 3.6. To get venv module we need to install python3-venv package to do so enter following command.

sudo apt install python3-venv

Now we can create Virtual Environment for Django Applications.

Create Virtual Environment

Create a new directory for your Django application and go inside the directory.

mkdir new_django_app && cd new_django_app

Now create virtual Environment by running following command. It will create directory named venv which includes supporting files, Standard python library, Python binaries, Pip package manager.

python3 -m venv venv

To start using the virtual environment we need to activate it. To activate the virtual environment run following command.

source venv/bin/activate

Now your path will change and it will show the name of your virtual environment (venv)

Install Django

Now install Django by using Pip (Python Package Manager).

pip install Django

Confirm the installation and Check the version typing following command.

python -m django –version

The output should be as given below. NOTE: you can get slightly different output.

Output:
2.1.4

Creating Django Project

Create a Django project by using django-admin utility named newdjangoapp. Enter following command to create new Django project.

django-admin startproject newdjangoapp

Now newdjangoapp directory will be created. Check the directory structure by using the following command. This directory has manage.py file used to manage the project and other Django specific files about database configuration settings, routes, and settings

tree newdjangoapp/

Output should be

newdjangoapp/
|– manage.py
`– mydjangoapp
|– __init__.py
|– settings.py
|– urls.py
`– wsgi.py

Now go inside newdjangoapp directory.

cd newdjangoapp

Now we need to migrate the database.

python manage.py migrate

Output should be:

Operations to perform:
Apply all migrations: admin, auth, contenttypes, sessions
Running migrations:
Applying contenttypes.0001_initial… OK
Applying auth.0001_initial… OK
Applying admin.0001_initial… OK
Applying admin.0002_logentry_remove_auto_add… OK
Applying admin.0003_logentry_add_action_flag_choices… OK
Applying contenttypes.0002_remove_content_type_name… OK
Applying auth.0002_alter_permission_name_max_length… OK
Applying auth.0003_alter_user_email_max_length… OK
Applying auth.0004_alter_user_username_opts… OK
Applying auth.0005_alter_user_last_login_null… OK
Applying auth.0006_require_contenttypes_0002… OK
Applying auth.0007_alter_validators_add_error_messages… OK
Applying auth.0008_alter_user_username_max_length… OK
Applying auth.0009_alter_user_last_name_max_length… OK
Applying sessions.0001_initial… OK

Create administrative user running following command.

python manage.py createsuperuser

NOTE: Above command can prompt you for Username, Password and Email Address for your user.

Testing the development server

Run development server using following command.

python manage.py runserver

The output should be:

Performing system checks…

System check identified no issues (0 silenced).
December 27, 2018 – 18:26:02
Django version 2.1.4, using settings ‘mydjangoapp.settings’
Starting development server at http://127.0.0.1:8000/
Quit the server with CONTROL-C.

NOTE: If you are using the virtual machine then you need to add your server IP address inside settings.py file.

Go to http://127.0.0.1:8000/ in your browser you will get following page.

django home page

You can go to admin page by visiting http://127.0.0.1:8000/admin/ page.

Enter username and password we have created recently after successful authentication you will be redirected to the administrative page.

django admin login page

Stop the development server pressing Ctrl+C in terminal.

Django home for admin

Deactivate The Virtual Environment

To deactivate virtual environment after work run following command.

deactivate

Conclusion

You have successfully learned how to install Django Web Framework on Ubuntu 18.04. If you have any queries please don’t forget to comment below.

NOTE: You can create multiple development environments repeating above steps.

Source

RoR or Ruby on Rails is an open source, cross-platform web development framework that provides a structure to the developers for their code. It helps them create applications and websites by abstracting and simplifying the repetitive tasks faced during development. It is called Ruby on Rails because Rails is written in the Ruby programming language, exactly how Symfony and Zend are written in PHP and Django in Python. Rails provide default structures for databases, web servers, and web pages. Famous applications like Soundcloud, Github and Airbnb are all based on Rails.

Ruby on Rails is licensed under MIT and was first released in December 2005. All of its repositories are available on Github, including the latest release to date.

This tutorial explains a step-by-step process for installing and configuring Ruby on Rails with all its prerequisites. Later, we will explain how to install and configure the PostgreSQL Database in order to create your first Rails project.The article also explains how to create a simple CRUD interface, making your application more interactive and useful.

We have run the commands and procedures mentioned in this article on a Ubuntu 18.04 LTS system. We are using the Ubuntu command line, the Terminal, in order to install and configure Ruby on Rails. You can access the Terminal application either through the system Dash or the Ctrl+Alt+T shortcut.

Ruby on Rails Installation

In order to install Ruby on Rails, you first need to have the latest versions of some prerequisites installed and configured on your system, such as:

• RVM-Ruby Version Manager
• Ruby
• Nodejs-Javascript runtime
• Ruby Gems-Ruby Package Manager

In this section, we will first have our system ready by first installing all these step-by-step, setting up their latest versions, and then finally install Ruby on Rails.

1. Install Ruby Version Manager (RVM)

The Ruby Version Manager helps us in managing Ruby installation and configuring multiple versions of Ruby on a single system. Follow these steps in order to install the RVM package through the installer script:

Step1: Add the RVM key to your system

Run the following command in order to add the RVM key; this key will be used when you install a stable version of RVM:

$ gpg –keyserver hkp://keys.gnupg.net –recv-keys 409B6B1796C275462A1703113804BB82D39DC0E3
7D2BAF1CF37B13E2069D6956105BD0E739499BDB

Step2: Install Curl

We will be installing RVM through Curl. Since it does not come by default with the latest versions of Ubuntu, we will need to install it through the following commands as sudo:

$ sudo apt install curl

Please note that only authorized users can add/remove and configure software on Ubuntu.

The system will prompt you with a Y/n option in order to confirm the installation. Please enter Y to continue, after which, Curl will be installed on your system.

Step3: Install the RVM Stable version

Now run the following command in order to install the latest stable version of RVM.

$ curl -sSL https://get.rvm.io | bash -s stable –ruby

This command will also automatically install all the required packages needed to install RVM.

The process will take some time depending on your Internet speed, after which RVM will be installed on your system.

Step4: Setup RVM source folder

Please note that the last few lines of the RVM installation output suggest running the following command:

$ source /usr/local/rvm/scripts/rvm

This is used to set the source folder to the one mentioned in the output. You need to run this command in order to start using RVM.

You might get the following output when setting up the source:

In that case, run the following commands on your system:

$ source ~/.rvm/scripts/rvm
$ echo “source ~/.rvm/scripts/rvm” >> ~/.bashrc
$ source ~/.bashrc

Now the source for RVM is set. You can check the version number of RVM installed on your system through the following command:

$ rvm –version

This output also ensures that RVM is indeed installed on your system.

2. Configure Latest Version of Ruby as System Default

When you install RVM, the latest version of Ruby is also installed on your system. What you need to do, however, is to set up your system to use the latest version of Ruby as the system default. Follow these steps to do so:

Step1: Setup RVM latest stable version

First, we need to update the RVM on our system with the latest stable version available on https://get.rvm.io

Run the following command to do so:

$ rvm get stable –autolibs=enable

Step2: Get the list of all available Ruby versions

The following command gives you the list of all Ruby versions released till date:

$ rvm list known

Through this list, please choose the latest version of Ruby available. As you can see in the output, Ruby 2.6.0 is the latest version available.

Step3: Install the latest Ruby version

Now install the latest version of Ruby that you have selected in the previous step, by running the following rvm command:

$ rvm install ruby-2.6

The process may take some time depending on your Internet speed, after which the selected number of Ruby will be installed on your system.

Step4: Set the latest version of Ruby as default

The following rvm command will help you in setting the latest installed version of Ruby as the system default:

$ rvm –default use ruby-2.6

You can see that now my system will be using Ruby 2.6.0-rc1 as the default Ruby version.

This can also be verified by running the following version command:

$ ruby -v

3. Install Nodejs and the gcc compiler

Before starting with the Rails development on Linux, we recommend using Nodejs as the Javascript runtime. It is a prerequisite for compiling Ruby on Rails asset pipeline.

Step1: Install the latest version of Nodejs

Use the following command in order to install the Nodesource repository to your system:

$ curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash –

Now install the latest version of Nodejs through the following apt command as sudo:

$ sudo apt install -y nodejs

The latest available version of Nodejs 10 will be installed on your system

Step2: Install the gcc compiler

The gcc compiler is another prerequisite that you need to install before performing any Rails development. Use the following command as sudo in order to install it:

$ sudo apt install gcc g++ make

4. Configure Latest Version of RubyGems as System Default

When you install RVM, RubyGems is also installed on your system. What we need to do, however, is to set up our system to use the latest version of RubyGems the system default. Ruby Gems is basically the Ruby on Rails package manager that comes with the command line tool-gem.

Run the following gem command in order to update the system to use the latest version:

$ gem update –system

Now when you check the version number through the following command, you will see that your system is using the latest version of RubyGems in the command line:

$ gem -v

5. Install Ruby on Rails

Finally, after installing all the prerequisites, we can now install Ruby on Rails on our system by following these steps:

Step1: Look up for the latest available version

The RubyGems website maintains all the versions of Ruby on Rails till date, on the following link:

https://rubygems.org/gems/rails/versions

Choose the latest version of Ruby on Rails that you would like to install. At the time of writing this article, the latest available version is 5.2.2

Step2: Install the latest Ruby on Rails version

You can install the latest version of Ruby on Rails through the gem command line tool as follows:

$ gem install rails -v 5.2.2

The installation process might take some time depending on your Internet connection.

After the installation is complete, run the following command to view the Rails version installed on your system.

$ rails -v

The command also verifies that Ruby on Rails is indeed installed on your system.

Rails Development

Ruby on Rails supports many databases such as SQLite, MySQL, and PostgreSQL. In this section, we will explain how to start with the Rails development with the PostgreSQL database. This will include:

• Installing PostgreSQL Database
• Configuring PostgreSQL and Creating Roles
• Your First Rails application
• Creating a simple CRUD with PostgreSQL database on Rails

1. Install and Setup PostgreSQL Database

Step1: Install PostgreSQL

Use the following apt command as sudo in order to install the PostgreSQL database and some other required packages:

$ sudo apt install postgresql postgresql-contrib libpq-dev -y

Step2: Start and enable the PostgreSQL service

Once PostgreSQL is installed, you need to start the ‘postgresql’ service through the following command:

$ systemctl start postgresql

The system will prompt you with an authentication dialog, as only an authorized user can enable services on Ubuntu. Enter the admin password and click the Authenticate button after which the service will start.

The next step is to enable the service through the following command:

$ systemctl enable postgresql

The system will prompt you with a similar authentication dialog multiple times; enter the admin password each time and click the Authenticate button after which the service will be enabled.

Step3: Verify installation

$ Please run the following command in order to view a details stats report of your PostgreSQL installation:

$ dpkg –status postgresql

2. Configure PostgreSQL and Create Roles

PostgreSQL applications can be created by user or roles. By default, a “postgres” user exists which is a superuser and it can create and migrate databases and also manage other user roles.

Initially, you can log in as sudo on PostgreSQL through the following command:

$ sudo -u postgres psql

Here you can change the password of postgres as follows:

postgress=# password postgres

Create a Role

A superuser can create a new user role through the following command:

$ create role “role_name” with createdb login password “‘password’”’ ;

Example:

postgress=# create role dev_rails with createdb login password ‘rockon123’ ;

We are creating a role by the name of “dev_rails”. This is a user that will create a db for our first Rails application.

A superuser can view the list of roles existing on PostgreSQL as follows:

postgress=# du

Use Ctrl+z to exit PostgreSQL.

3. Your First Rails application

Now we will create our first Rails application with PostgreSQL as the default database. This involves the following steps:

Step1: Create a new Rails application

Create a new project by the name of “firstapp”, or any other name, through the following command and specify PostgreSQL as the database:

$ rails new firstapp -d postgresql

This will create a project folder in your home folder as follows:

$ ls

Step2: Configure your Rails project to incorporate the PostgreSQL user role

Now we want the user role we created in PostgreSQL to be able to create a database in the Rails application. For this, you need to edit the database.yml file located in your newly created application’s folder in the /config/ folder.

Move to your first application and then the config folder as follows:

$ cd /firstapp/config

Here you will see the database.yml file. You can edit this file through your favorite text editor. We will be doing so through the Nano editor by using the following command:

$ nano database.yml

In this file, you will be able to see mainly three sections:

• Development
• Test
• Production

We will need to configure the Development and Test sections of the file.

Make the following configurations in the Development section

database: firstapp_development username: dev_rails password: rockon123 host: localhost port: 5432

And, the following in the Test section:

database: firstapp_test username: dev_rails password: rockon123 host: localhost port: 5432

Note: Please make sure that the syntax is correct. Each line should be preceded by 2 spaces and NOT tabs.

Save the file by pressing Ctrl+X, then Y and then by hitting Enter.

Step3: Generate and then migrate the Database

Generate the database through the following rails command:

$ rails db:setup

Please make sure that there are no errors. Most errors are due to the wrong syntax in the database.yml file or the inconsistency in the username and password from the one you created in PostgreSQL.

After the successful generation, migrate the database through the following rails command:

$ rails db:migrate

Step4: Start the Puma Rails web server

After completing the application setup, please enter the following command in order to start the default Puma web server:

$ rails s -b localhost -p 8080

Or in our case,

$ rails s -b 127.0.0.1 -p 8080

After this command, your first Rails application is running on the local host at port 8080.

Step5: Open the default Rails Project Homepage

You can view your database successfully being hosted on the default Rails Project homepage by entering this URL in one of your web browsers:

http://localhost:8080/

You can also use your localhost IP, like us, in the above-mentioned URL:

You can not perform any CRUD operation on this simple application. Follow the article some more in order to make your application a little more interactive.

4. Create a simple CRUD with PostgreSQL database on Rails

Let us make our application more interactive by implementing a CRUD(Create, Read, Update, Delete) interface.

Step1: Create a Scaffold in Rails

Run the following command in order to create a scaffold in your Rails application folder

$ rails g scaffold Post title:string body:text

Then migrate the database by running the following command:

$ rake db:migrate

Step2: Run the application on Puma Rails Web Server

Next, run your application on the localhost by running the Puma web server again through the following command:

$ rails s -b localhost -p 8080

You can also use your localhost IP, like us, for the above-mentioned command:

$ rails s -b 127.0.0.1 -p 8080

Step3: Open the ‘Posts’ page in Rails Project

You can view your database successfully being hosted on the Rails Project page by entering the URL in one of your web browsers:

http://localhost:8080/posts/

Or use a localhost IP like us:

http://127.0.0.1:8080/posts

You will be able to see a simple CRUD interface through which you can create, edit, show and destroy posts.

When I created a post using the New Post link, here is how my posts page looked like:

You have now successfully completed the entire process of installing Ruby on Rails on your Ubuntu and then creating a sample application using the PostgreSQL database. This will serve as a basis for you to develop more productive and interactive database applications through Ruby on Rails.

Source

Your Linux machine is only as good as you make it. To make it into a powerful machine, you need to install the right packages, use the right configurations among a host of other things. Talking about packages; in this article I would be taking a primer on the APT package management tool. Similar to YUM for RHEL(RedHat Enterprise Linux) based Linux distributions—which was discussed here—APT(Advanced Packaging Tool) is for managing packages on Debian and Ubuntu based Linux distributions.This article isn’t planned to discuss all the powers of the APT package management tool, instead it is intended to give you a quick look into this tool and how you can use it. It would serve well for reference purposes and understanding how the tool works. Without much ado, let’s get started.

Location

Just like many Linux tools, apt is stored in the /etc directory—contains the configuration files for all the programs that run on Linux systems—and can be viewed by navigating to the directory.

Apt also has a configuration file which can be found in the /etc/apt directory with the file name apt.conf.

You would be doing a lot of package installations with apt, therefore it would go a long way to know that package sources are stored in a sources.list file. Basically, apt checks this file for packages and attempt to install from the list of packages—let’s call it a repository index.

The sources.list file is stored in the /etc/apt directory and there is a similar file, named sources.list.d. It isn’t actually a file, but a directory which keeps other sources.list files. The sources.list.d directory is used by Linux for keeping some sources.list files in a separate place—outside the standard /etc/apt directory.

The confusion: APT vs APT-GET

Yes, a lot of people actually mistake apt to be the same as apt-get. Here’s a shocker: they are not the same.

In truth, apt and apt-get work similarly however the tools are different. Let’s consider apt to be an upgrade on apt-get.

Apt-get has been in existence before apt. However apt-get doesn’t exist in isolation as it works together with other apt packages such as apt-cache and apt-config. These tools when combined are used to manage linux packages and have different commands as well. Also these tools are not the easiest to use as they work at a low level, which an average Linux user couldn’t care less about.

For this reason, apt was introduced. The version 1.0.1 of APT has the following on the man page, “The apt command is meant to be pleasant for end users and does not need to be backward compatible like apt-get.”

Apt works in isolation and doesn’t need to be combined with other tools for proper Linux administration, plus it is easy to use.

For an average Linux user, the commands are all that matter. Through the commands, tasks are executed and actual work can be done. Let’s take a look at the major apt commands.

Get Help

The most important of all the commands to be discussed in this article is the command used to get help. It makes the tool easy to use and ensures you do not have to memorize the commands.

The help provides enough information to carry out simple tasks and can be accessed with the command below:

You would get a list of various command combinations from the result, you should get something similar to the image below:

If you desire, you could check out the apt man pages for more information. Here’s the command to access the man pages:

Search for package

For a lot of operations, you would need to know the exact name of a package. This and many more uses are reasons to make use of the search command.

This command checks all the packages in the repository index, searches the keyword in the package descriptions and provides a list of all packages with the keyword.

Check package dependencies

Linux packages have dependencies, these dependencies ensure they function properly as the packages break when the dependencies break.

To view a package’s dependencies, you use the depends command.

apt depends <package name>

Display package information

Displaying a package’s dependencies is one information you would find useful. However, there are other package details you can get. For me, it would be less productive to memorize all the commands to access other details such as the package’s version, download size etc.

You can get all of a package’s information in one attempt using the apt command as seen below:

Install package

One of Linux’s strongest points is the availability of lots of powerful packages. You can install packages in two ways: either through the package name or through a deb file—deb files are debian software package files.

To install packages using the package name, the command below is used:

apt install <package name>

As stated earlier, you need to know the package name before using it. For example, to install Nginx the command would be apt install nginx.

The other means of installing packages is the through the deb file if available. When installing a package through its deb file, apt fetches the package dependencies itself and downloads it so you do not have to worry about them.

You can install deb files using the absolute path to the files with the command below:

apt install </path/to/file/file_name.deb>

Download package

If for some reason, you need to download a package without having it installed, you can do so using the download command.

This would download the package’s deb file into the directory where the command was run. You can download packages using the command below:

apt download <package name>

If you are then interested in installing the .deb file, you can then install using the install command.

Update repository index

Remember we talked about sources.list earlier? Well, when a new version of a package is released, your linux machine is not able to install it yet because it would not indicate. To have it indicate, it needs to reflect in the sources.list file and this can be done using the update command.

This command refreshes the repository index and keeps it up-to-date with the latest changes to the listed packages.

Remove packages

Packages break. Packages become obsolete. Packages need to be removed.

Apt makes it easy to remove packages. Here are different conditions to removing packages: removing the binary files and keeping the config files, removing the binary files and the config files.

To remove the binary files alone, the remove command is used.

apt remove <package name>

More than one package can be removed, so you can have apt remove nginx top to remove the Nginx and top packages at the same time.

To remove the configuration files, the purge command is used.

If you wish to do both at once, the commands can be combined as seen below:

apt remove –purge <package name>

Before proceeding, it should be known that when packages are removed, their dependencies remain i.e. they are not removed too. To remove the dependencies while uninstalling, the autoremove command is used as seen below:

apt autoremove <package name>

List packages

Yes, you can have the packages on your Linux machine listed. You can have a list of all packages in the repository index, installed packages and upgradeable packages.

Regardless what you intend doing, the list command would be used.

The command above is used to list all the packages available in the repository index.

The command above is used to list the packages installed on your Linux machine.

The command above is used to list the packages installed on your machine that have upgrades available.

Updating packages

When it comes to packages, it’s not all about installing and removing packages; they need to be updated too.

You can decide to upgrade a single package or all packages at once. To update a single package, the install command is going to be used. Surprising right? Yes, however we are going to be adding the –only-upgrade parameter.

apt install –only-upgrade <package name>

This works when you intend upgrading just one package. However, if you want to upgrade all the packages you would need to use the upgrade command.

The following command would be used to make such an upgrade:

It should be noted that the upgrade command doesn’t remove dependencies and even if the upgraded packages do not need them anymore i.e. they are obsolete.

System upgrade

Unlike the regular upgrade, the full-upgrade command to be discussed here performs a complete system upgrade.

With the full-upgrade command, obsolete packages and dependencies are removed and all packages (including system packages) are upgraded to their latest versions.

The command for doing this, is full-upgrade as seen below:

Conclusion

Apt is a powerful tool that makes the use of Debian and Ubuntu based Linux distributions a wonderful experience. Most of the apt commands listed here require root permissions, so you may need to add sudo to the start of the commands.

These commands are just a tip of the iceberg of the immense powers that the apt tool possesses, and they are powerful enough to get you comfortable with managing packages on your Linux machine.

Source