Programming in Linux

It’s time to talk about programming. In Linux we can work with pretty much every programming language, so in the end of the day it is only matter of choice or specifics of task. To start with any of programming languages – all you need is text editor and interpreter/compiler, get one and you can do pretty much what ever you want.

#C++
This old-school guy is very useful for many purposes, especially when the talk comes to high performance. to start with it first thing to do is to check whether compiler is installed. In terminal simply type ‘g++’ and if something like ‘no input file’ appear – that means you already have. So let’s start with program.  In some text editor, create following program:

#include<iostream>
using namespace std;
int main()
{
cout << “Hello world” << endl;
return 0;
}

Save it, for example, with name ‘HelloCpp.cpp’. And in the command line compile like that: “g++ -o helloCpp helloCpp.cpp”, where parameter ‘-o’ specifies a name for output file. Here we go, to run the program simply type “./helloCpp” and that’s it.
CppScreen

#Java
Mostly used in production for many years programming language. Just as before ensure that you have development kit by following command “sudo apt-get install openjdk-7-jdk”. Now lets go to text editor and do same program:

class HelloJava {
public static void main(String[] args){
System.out.println(“Hallo world”);
}
}

To compile it use following “javac HelloJava.java”, and then just run it “java HelloJava”.
JavaScreen

#Ruby
This language along with Python suits very well for quick development. To start, firstly get interpreter and libraries by command “sudo apt-get install ruby-full”.  When it is installed just as with any other language create a file ‘helloRuby.rb’ and in that file simply put:

puts ‘Hello world!!!’

Since Ruby is scripting language – there is no need to have entry point for a program. After that simply type following command: “ruby helloRuby.rb”. More than that ruby has Interactive Ruby Shell, which can be called in command line ‘irb’, and it gives possibility to run ruby commands in real time without need to create source code file.
RubyScreen

#Octave
Octave is high-level interpreted language with specific purpose – mathematical computations. It perfectly suits for algorithm prototyping. It can be installed with simple command “sudo apt-get install octave”. Octave can be used only through interactive shell, however it doesn’t mean that no files can be used. Let’s create file “helloOctave.m” and in that file we will define following function:

function helloOctave(a, c)
x = (1:10)’
y = x.*a+c
plot(x, y);
endfunction

Then, we just need to run Octave by command ‘octave’, and call the function “helloOctave(5,2)”
OctaveScreen

#Python
To try this one, simply either create file and run it “echo ‘print “Hello”‘ > helloPy.py” and then “python helloPy.py” or just call interactive shell by command “Python”.

###Have fun, and don’t forget – Chuck Norris is watching for you###
timthumb.php

Ssh and openSsh server

#OpenSsh-server
So first of all to start I need to have a server to provide connection. To do so – type in terminal “sudo apt-get install openssh-server”. You won’t have a time even to make a cup of coffee ’cause your server will be up and running after couple of seconds. Now to test it I will create new user and connect to my own computer through ssh. “sudo adduser [nameForUser]” in my case it was like “sudo adduser testalex123″. And yeaps – new user is created.

#Ssh connection
Now for test purposes it is time to logon. To do so the following command should be executed: “ssh localhost@testalex123″ where localhost is domain name for my own ip address and after (at) sign comes user name. The same can be done through typing the ip, to know your ip is enough to type “ip addr”. So my private ip inside my lan is 192.168.0.10. So let’s try that one. And as I said the following: “ssh testalex123@192.168.0.10″ works exactly the same way just fine.

#Doing things remotely
After successful connection – everything you can do on your own computer – you can do as well remotely, or in my case being logged on with one account I imitate that my other account is located somewhere else. But yeah, in previous post “Appache and MySql” I already installed web server and set it up to user own directories. So let’s create a personal web page for our new, figuratively speaking, remote user using ssh. After establishing connection check the working directory by command “pwd”. If it shows “/home/testalex123″ then we are good to go. Firstly we need folder for personal web page, so type following: “mkdir public_html” and then simply go into it “cd public_html”. Now we need an index page and some simple html mark-up to test things. To do so, we can used terminal based text editor, but since we just need to test things we can simply type command: “echo ‘<h1>Hello</h1><p>ssh working properly. <h3>We are online and ready</h3>’ > index.html”. Alright so the final part is actual test – navigate browser to “localhost/~testalex123″
SshTestScreen
So if you see that in your browser – then the surgery was successful. Yes, we manged to do things figuratively remotely and what is more important – it wan no more difficult then doing things on your own machine. That’s it!

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Apache and MySql

#Apache
So… Apache is apache – nothing to say – just install and use it. To do so in the terminal the following command should be executed: “sudo apt-get install apache2″. And if you manage to type your sudo password correctly – after couple of seconds it will be installed. You even can check it right away by navigating your browser to “localhost”.
ApacheWorksScreen
“It works!” your browser will say – no jokes. But to start creating your personal page would be nice to change physical directory on your computer for websites. The easy way is to set it up under user home directory where you and other user can have dedicated pages. To do so in good old terminal the following command should be executed – “sudo a2enmod userdir” after which the server need to be restarted – “sudo service apache2 restart”. Now to complete the preparation a directory “public_html” has to be created under user’s home directory. To check that it works – create simple “index.html” file under public_html directory and define there simple test paragraph or header.
userPageScreen
Here we go. Quick and easy just in few minutes we can start creating a web page.

#MySQL
Well, you know, sooner or later you’ll come to a point where there will be need for database and MySQL is a good choice. To manage with it you can use either phpMyAdmin or command based client. Today I’m in a command line mood so just type in terminal the following command: “sudo apt-get install mysql-server mysql-client”. And yeps, now we can play with it a bit. You can run it by command “mysql -u root -p” and then just create first database.

For test purposes, I’ll create database where information about courses I’m currently taking will be kept.

  • So “Create Database hhCourses”.
  • The next thing is to create little teacher table: “CREATE TABLE Teacher(id INTEGER PRIMARY KEY, name NVARCHAR(50), email NVARCHAR(50));”.
  • Second table I need is Room: “CREATE TABLE Room(number INTEGER PRIMARY KEY, type NVARCHAR(50));”.
  • After that I need table which would represent course modules: “CREATE TABLE Module(id INTEGER PRIMARY KEY, code NVARCHAR(10));”.
  • And finally the main course table: “CREATE TABLE Course(id INTEGER PRIMARY KEY, name NVARCHAR(100), dayOfWeek NVARCHAR(10), courseTime TIME, moduleId INTEGER REFERENCES Module(id), roomNumber INTEGER REFERENCES Room(number), teacherId INTEGER REFERENCES Teacher(id));”.

showTablesScreen

Now it is time to put into it some data:
INSERT INTO Teacher VALUES(1, ‘Pekka’, ‘pekka@mail.com’);
INSERT INTO Teacher VALUES(2, ‘Juhani’, ‘juhani@mail.com’);
INSERT INTO Teacher VALUES(3, ‘Tero’, ‘tero@mail.com’);

INSERT INTO Module VALUES(1, ‘SYS’);
INSERT INTO Module VALUES(2, ‘DAT’);
INSERT INTO Module VALUES(3, ‘ITP’);

INSERT INTO Room VALUES(4004, ‘lab’);
INSERT INTO Room VALUES(1001, ‘lecture’);
INSERT INTO Room VALUES(5001, ‘lab’);
INSERT INTO Room VALUES(5009, ‘lab’);

INSERT INTO Course VALUES(101, ‘Development project’, ‘MON’, ’10:00:00′, 1, 4004, 1);
INSERT INTO Course VALUES(102, ‘Linux’, ‘THU’, ’12:00:00′, 2, 5001, 3);
INSERT INTO Course VALUES(103, ‘Java’, ‘WED’, ’16:00:00′, 3, 5009, 2);
INSERT INTO Course VALUES(104, ‘Mobile’, ‘FRI’, ’08:00:00′, 3, 5009, 2);

Check:
tableDataScreen

That’s it folks! Play around and enjoy.

Terminal hands-on and logs

Alright it is time to install couple of apps without using graphical interface of package manager and look into logs a bit.

#1 – Game
First of all it is a perfect time to play some game. And after command “apt-cache search rpg” simply because rpg is one of my favourite genre,  the console gives me a lot of choice, but after reading some of the description I decided to go with “freedroid”, so with simple command “sudo apt-get install freedroid” in few seconds I can start playing. And I should say it is incredible. A lot of action, it is not rpg at all but still playable if you are fan of 8-bit music.

freeDroidScreen

#2 System monitoring

So searching for some tool to monitor system activity – search game me an option called “ksysguard”, Seems that it has quite many dependencies and because of my slow internet it takes a while to install. Seems that everything is running smoothly and nothing to worry.
ksysguardScreen

#3 Glitch in the matrix
You know that – matrix has you. But don’t be upset and just follow a white rabbit and chose right pill. An application cMatrix will turn you console into matrix monitor as well as it is possible to run the program in a screen saver mode.
cmatrixScreen

#Logs
Logs are located in var/log directory so being in var working directory typing a command “tail -f log/*” will allow you to monitor and follow all logs in the directory. And for example, changing a language will affect in changes in Xorg.0.log
termScreen1

Or for example, opening a date and time settings will cause the changes in syslog like that
termScreen2

#Epilogue

Terminal is very efficient, fast and useful tool in most of the activities but only as long as you know how to use it. There is no way to read a book and learn all the commands you might need. So the only option is to learn “at-need” by doing.
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Command line and arguments

In many cases command line is more handy to use. But that’s applies only if you know what to do. Well the basic commands are quite easy “ls” – list files and folders in current directory, “pwd” – print working directory, “cd” – change directory and so on. But on top of that with different commands it is possible to use arguments or so-called flags.

One of the example would be “ls -a” which means something like list All the folders and files in the directory. When it comes to application it is always possible to see the arguments that particular application can accept using “-h” parameter, for example “nano -h”, and then I can for example find a “-V” parameter which with most of other applications as well will display current version and year of build of the application. The other example would be with apt-get package manager, it is possible to pass a parameter “-y” so that all the question will be answered with yes.

There are many other flags and it is quite difficult to learn them and with which application they can be used without really trying out at need. So probably it would be a good idea to learn command line commands and arguments while you actually trying to do something with terminal. Over and out.

Apps with Software Center

Today is the day… To get into Ubuntu software center and install couple of apps. Based on my personal experience the software center is quite good thing, however for new user it’s might be a little difficult to learn about open source software alternatives for apps they used previously. But google search – helps a lot. So in the end it is nothing but pleasure.

Here we go
First of all I have one problem – I sleep soundly. Even if in nearest neighbourhood an earthquake occurred, it wouldn’t disturb me even a bit. So the usual case is that – in order to wake up at 6 a.m. I need couple of loud alarm clocks around. One of them can be found in software center – Alarm clock applet.

AlarmCenterScreen
The App is just amazing. Easy, Simple, straight forward and what most important is reliable. What else you need to ensure that you’ll wake up in time?

AlarmAppScreen

Numero deux
Well, if you want to succeed in life – waking up in time is not the only thing you need to ensure. So called “To Do” list is what each and every busy person should have, otherwise anarchy and chaos in task management might simply ruin your life. For that purpose one of the best apps in software center is ‘Nitro’
NitroCenterScreen
It has not only a GUI client, but also can be assessed through browser as a web app. As many other linux apps it keeps that simplicity that I like so much – nothing extra – just exactly what you need to accomplish your goals.
NitroAppScreen
Easy to use, easy to set up and order items in the list. It has search box as well in case you are very lazy person and list will expand insanely over the time.

Numero trois
And finally just to stay busy – we need an IDE. There are plenty, but at that time I’ll go with Eclipse.
EclipseCenterScreen
Installation is nice and easy for all the apps, it takes literally seconds for package manager to resolve dependencies and download app. And you know what? – linux doesn’t ask you for reboots when you installing or deleting something as windows does it.
EclipseAppScreen

Anyway, after downloading goes usual procedure – define working directory and create your new awesome project. That’s pretty much it – there is nothing else to tell, since the software center is so nice and easy to use. Hope you’ll enjoy. Over and out.

Linux try out

First of all the reason – Why
Here might come a question why would you do that… Answer is quite simple:

  • It comes for free, no tricks, no catches.
  • Linux is faster than windows
  • More freedom to change things
  • You might be tired of windows crashes all the time

And here is my favorite:

  • I tired that windows asks for reboots almost daily, whatever happens windows in panic wants you to reboot the system, and time to time it even doesn’t ask you for permission to do so…. Maaaaan… You know how many times I needed to reboot Linux?!? – Once!! right after installation.

installing

Starting
First of all you need to check system type (32 or 64). To do that the easiest way – right click “Computer” icon on the desktop or in the file explorer and chose properties. There you will find system type.

SystemType

Downloading Distribution
For that time I will go with Xubuntu, though I have already Ubuntu installed. http://xubuntu.org/ there you can read about it a bit, and after just press “Get Xubuntu”. I would recomend LTS (Long Term Support) release. Then you have a choice to use torrent for downloading or not. Pick the one that matches your System type (32/64) as we’ve just checked it. Through torrent it took for me about 20 minutes to download the distribution.

Creating Live CD / USB
To burn a disk image on CD – you can use Nero, Deamon Tools Lite or Alcohol 120%. I will go with USB option. To create Live USB – I will use Universal USB installer. In just free steps the magic will happen. Be careful, all the data from Usb will be erased, so before doing that copy files from Usb somewhere else.
UniversalUsb

Back ups
Usually everything going alright, but back ups is good practice anyway. Get external hard drive and leave your computer copying all the files you need for a night. In case you really worry about your Windows – you can create a System image and recovery CD

(Notes: recovery CD isn’t the same as installation CD, so you won’t be able to use it if you unistall windows. You cannnot create recovery USB, so in case you don’t have internal CD drive – buy an external one.)

To create both System Image and recovery CD – go to Control Panel/Back up and Restore.
SystemImage

Try out
Turn off your computer, plug in Live USB. If you have newer computer – for sure there will be Boot option, where you can chose which device from operating system should be loaded. Otherwise you can edit Boot order in BIOS. Usually to go there you need to press F12 right after pressing power button, however on a different computers it might be something else (F10, F2). Press Try Xubuntu. Check things out and if it is fine for you – install, either erasing windows, or aside (dual boot). What to do after – enjoy!

Different distributions
Xubuntu is not the only one Linux distribution. Easiest way to chose – download several of them and run them under virtual machine (VirtualBox).
meme-richar
Most popular ones for the last 6 months are:

  • Mint
  • Debian
  • Ubuntu
  • Mageia
  • Fedora

Outcomes
After installing Ubuntu I can name couple of good changes from my personal expirience:

  • It is really faster than Win 7 (boot and applications)
  • It requires less resources (I can declare that, based on the temperature of the laptop)
  • Getting apps through repositories is more handy
  • Sound is louder and has higher quality
  • Workspaces are awesome
  • It works without reboots

However there is one small thing: for some reason Skype doesn’t work… Anyway, I’m pretty much satisfied.
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