MANI-G

speeding up and saving data in chrome browser

2015-07-13T04:46:00.000-07:00

Here in India we don't afford an unlimited internet plan or high speed internet(mostly). I came through some awesome chrome extensions to the rescue. I checked most of the extension they work seamlessly in my chrome browser in ubuntu 14.04.

If you're using windows you can consider an awesome ucbrowser that forked from chromium web browser. that support all the extensions of google chrome browser. we can grab it from pc.ucweb.com. It as its own cloud compression technology known as speedmode that can reduce the data transmitted over internet. Check it yourself.

So, here are the chrome extensions used to reduce internet data.

1. Google data saver extension:

You may seen this on your android devices, and now it's available for pc version of chrome. It uses the google's own server to optimize the pages that we request. It will not work with SSL or HTTPS sites. and it works damn nice with ordinary sites. grab it here: data-saver-beta and it's currently a beta release.

2. Disconnect:

Did u know, the page that loads in our browser not only loads the information that we want. It contains lots of tracking websites, ads, scripts, etc., they eat some bandwidth also. So this extension
will block all those trackers from the websites. grab it here: Disconnect extension.

3. uBlocker origin:

Another blocker that block unwanted ads and trackers. doesn't eat much of the hardward resources. it consumes less memory and cpu cycles unlike adblock plus. try it, it's so cool. grab it: ublock-origin

4. data-compression-proxy:

Another data saver extension. works same as google data-saver extension. try it yourself
grab it: data-compression-proxy. also there is a skyzip proxy extension that serves same as above.

5. ultimate user agent switcher url sniffer:

It's my suggestion that to use some user agent switchers to switch to the mobile devices such as windows phone or something. desktop version of websites are heavy and loads lots of data.
If i goto facebook's desktop version it eat almost 20mb of data. So that i switch to mobile device that load mobile version of facebook to save my data. :)

First Graphic program in C

2014-07-20T08:52:00.002-07:00

Current semester i have a Computer Graphics as a subject.
Here is my first program that implements the
bresenham's circle drawing algorithm to draw a circle
and with some lines i created a smiley : )

#include "stdio.h"
#include "graphics.h"

void brecircle(xc,yc,r)
{

int x,y,p;
x=0;
y=r;
putpixel(xc+x,yc-y,1);

p=3-(2*r);

for(x=0;x<=y;x++)
{
if (p<0)
{
y=y;
p=(p+(4*x)+6);
}
else
{
y=y-1;

p=p+((4*(x-y)+10));
}

putpixel(xc+x,yc-y,15);
putpixel(xc-x,yc-y,15);
putpixel(xc+x,yc+y,15);
putpixel(xc-x,yc+y,15);
putpixel(xc+y,yc-x,15);
putpixel(xc-y,yc-x,15);
putpixel(xc+y,yc+x,15);
putpixel(xc-y,yc+x,15);
}
}

int main() {
  int x,y;
  int gd = DETECT, gm=0;
  initgraph(&gd,&gm,"");
  x=getmaxx()/2;
  y=getmaxy()/2;
  brecircle(x,y,150);
  brecircle(x-50,y-50,19);
  brecircle(x+50,y-50,19);
  line(x,y,x+20,y+20);
  line(x,y,x-20,y+20);
  line(x-20,y+20,x+20,y+20);
  line(x-40,y+50,x+40,y+50);
  getch();
  closegraph();
  return 0;
}

output:

wordpuzzle solver

2014-06-16T10:07:00.000-07:00

Most of the *nix systems contains the wordlist.
This script will use that wordlist to search the words for the given pattern.

#!/usr/bin/python
import re
import sys

if len(sys.argv[:]) != 2:
 print "usage: ./puzzle.py 'pattern'"
 exit(0)

pattern = sys.argv[1]
length = len(pattern)
pattern = pattern.replace('?','\w')
words = open('/usr/share/dict/words','r')
print ''
for word in words:
 if len(word)== int(length)+1 and re.search(pattern,word):
  print word.strip()

Also made a gui for that application

You can get the full source code for this app in https://github.com/manimaran990/wordpuzzle

Pronunciation script in python

2014-06-14T04:41:00.005-07:00

Frequently i had a visits to google to search for some word pronunciations.
So I wrote this small script to save my time.
you need to install mpg123 before you run this script
by

$ sudo apt-get install mpg123

spellit.py

#!/usr/bin/python

import os
import sys

url = 'http://ssl.gstatic.com/dictionary/static/sounds/de/0/'
if len(sys.argv[:]) != 2:
 print 'usage: ./spellit.py word'
 exit(0)

word = sys.argv[1]

final = url+word+'.mp3'
os.system('mpg123 -q %s'% final)

Sneak-peek at py-qt

2014-06-04T01:17:00.000-07:00

Learned some py-qt to build a front-end for the sms api

#!/usr/bin/python

import sitsms
import sys
from PyQt4 import QtGui, QtCore

class Sitsms(QtGui.QWidget):

    def __init__(self):
        super(Sitsms, self).__init__()

        self.initUI()

    def initUI(self):

        number = QtGui.QLabel("Number ",self)
        number.move(20,20);

        message = QtGui.QLabel("Message ",self)
        message.move(20,60);

        self.numberEdit = QtGui.QLineEdit(self)
        self.numberEdit.resize(190,24);
        self.numberEdit.move(80,20);
        self.messageEdit = QtGui.QTextEdit(self)
        self.messageEdit.resize(220,200)
        self.messageEdit.move(80,60);

        self.sendbtn = QtGui.QPushButton("send",self)
        self.sendbtn.setStyleSheet("QPushButton:pressed { background-color: green }"
                      "QPushButton:released { background-color: gray }" )
        quitbtn = QtGui.QPushButton("Exit",self)

        self.sendbtn.clicked.connect(self.buttonClicked)
        self.sendbtn.move(80,280)

        quitbtn.clicked.connect(QtCore.QCoreApplication.instance().quit)
        quitbtn.move(200,280)

        self.setGeometry(300,350,320,320)
        self.setFixedSize(320,320)
        self.setWindowTitle('SitSms')
        self.show()


    def buttonClicked(self):
        numlen = len(self.numberEdit.text())
        msglen = len(self.messageEdit.toPlainText())

        if numlen==0:
            QtGui.QMessageBox.information(self,'info',"please fill your number",1)
        elif numlen>10:
            QtGui.QMessageBox.information(self,'info',"number count must be 10 digits",1)
 else:
     num = self.numberEdit.text()
     if msglen>145:
         QtGui.QMessageBox.information(self,'info',"your message is trimmed to 145 chars",1)
     message = self.messageEdit.toPlainText()[:145]
     sitsms.loginsite()
     sitsms.sendsms(num,message)
     QtGui.QMessageBox.information(self,'info','Message delivered to '+num,1)

def main():
    app = QtGui.QApplication(sys.argv)
    ex = Sitsms()

    sys.exit(app.exec_())

if __name__ == '__main__':
    main()

find full source code at github

My First Applicaiton in Rails

2014-05-20T11:12:00.000-07:00

Here is my gpa calculator app in rails. cgpacalc.herokuapp.com

with some bootstrap. It calculates the gpa and allow users to signup and save their marksheets for their future references.

some vim tips:

I used vim editor for this development. There is a plugin called vim-rails it can make the development much easier.

vi editor should be on your box.

need to install vim-pathogen before installing vim-rails

mkdir -p ~/.vim/autoload ~/.vim/bundle; \
curl -LSso ~/.vim/autoload/pathogen.vim \
    https://raw.github.com/tpope/vim-pathogen/master/autoload/pathogen.vim


then add this on .vimrc file

execute pathogen#infect()

after that we can install vim-rails by



cd ~/.vim/bundle
git clone git://github.com/tpope/vim-rails.git
git clone git://github.com/tpope/vim-bundler.git
open vim and type :Rails
Baisc commands:
:Rmodel user
:Rcontroller application
:Rhelper navigation
:Rview sessions/new
:Rfunctionaltest sessions
:Runittest user

GPA calculator in RUBY

2014-05-16T00:48:00.004-07:00

#!/usr/bin/env ruby

=begin
Prgram : CGPA calculator
Date : May 16, 2014
Author : ManiG
License : GPL2.0
Version : 1.0
=end

sum=0.0
grade = {"S"=>10,"A"=>9,"B"=>8,"C"=>7,"D"=>6,"E"=>5,"U"=>0}
tot_credits = 0
tot_egrades = 0
print "enter no. of subjects : "
sub_count = gets().to_i
sub_count.times do |c|
    print "enter subject#{c+1}'s credit : "
    credit = gets().to_i
    tot_credits += credit
    print "enter subject#{c+1}'s earned grade :(only 'S','A','B','C','D','E','U') : "
    e_grade = gets().chomp.upcase
    tot_egrades += grade[e_grade] 
    sum += grade[e_grade]*credit
end
gpa = sum/tot_credits
puts
puts "Credits Earned #{tot_credits}"
puts "Grade points earned #{tot_egrades}"
puts "GPA #{format("%.4f",gpa)}"
puts "CGPA #{format("%.4f",gpa)}"
puts
puts "Percentage [=(cgpa*10)-7.5] #{format("%.4f",(gpa*10)-7.5)}"

ARP/RARP full simulation program

2014-03-24T10:22:00.000-07:00

server.c

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"
#include "netinet/in.h"
#define SA struct sockaddr

struct IPmac {
			 char ip[100];
			 char mac[100];
	   };


int main() {
	   int sockfd,len,i;
	   struct sockaddr_in servaddr;
	   char buff[30],temp[30],ip[30],mac[30];
	   int flag=0;

	   struct IPmac in[3]={ 
			 {"10.1.1.8","44:dd:22:11:33"},
			 {"127.0.0.1","33:aa:fe:4e:2d"},
			 {"10.1.8.5","23:a3:5d:33:9d"}
	    };

	   //printing table
	   printf("ip\t\tmac\n");
	   for(i=0;i<3;i++) 
	   {
			 printf("%s\t%s\n",in[i].ip,in[i].mac);
	   }

	   //create socket
	   sockfd = socket(AF_INET,SOCK_DGRAM,0);

	   //fill structure
	   servaddr.sin_family = AF_INET;
	   servaddr.sin_port = htons(9999);
	   servaddr.sin_addr.s_addr = INADDR_ANY;

	   //bind
	   bind(sockfd,(SA*)&servaddr,sizeof(servaddr));

	   //get ip from client
	   len=sizeof(servaddr);
	   recvfrom(sockfd,ip,sizeof(ip),0,(SA*)&servaddr,&len);

	   for(i=0;i<strlen(ip)-1;i++) {
			 temp[i]=ip[i];
	   }
	   temp[i]='\0';
	   printf("received IP :%s\n",temp);

	   //searching in table for equivalent mac
	   for(i=0;i<3;i++) {
			 if(strcmp(temp,in[i].ip)==0) {
				    strcpy(mac,in[i].mac);
				    break;
			 }
	   }

	   printf("mac address is %s\n",mac);
	   sendto(sockfd,mac,sizeof(mac),0,(SA*)&servaddr,len);

	   //rarp simulation
	   //recv mac address
	   bzero(mac,sizeof(mac));
	   recvfrom(sockfd,mac,sizeof(mac),0,(SA*)&servaddr,&len);
	   printf("received mac address :%s",mac);
	   //store in temp
	   bzero(temp,sizeof(temp));
	   for(i=0;i<strlen(mac)-1;i++) {
			 temp[i]=mac[i];
	   }
	   temp[i]='\0';
	   bzero(ip,sizeof(ip));

	   //check in table
	   for(i=0;i<3;i++) {
			 if(strcmp(temp,in[i].mac)==0) {
				    strcpy(ip,in[i].ip);
				    break;
			 }
	   }
	   printf("ip address :%s\n",ip);
	   sendto(sockfd,ip,sizeof(ip),0,(SA*)&servaddr,len);
	   return 0;
}


client.c

#include "stdio.h"
#include "stdlib.h"
#include "string.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"
#include "netinet/in.h"
#define SA struct sockaddr

int main() {
	   int sockfd,len;
	   char ip[30],mac[30];
	   struct sockaddr_in servaddr;

	   //creating socket
	   sockfd = socket(AF_INET,SOCK_DGRAM,0);

	   //fill structure
	   servaddr.sin_family = AF_INET;
	   servaddr.sin_port = htons(9999);
	   servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");

	   //send ip address
	   printf("ARP SIMULATION\n");
	   printf("enter ip address :");
	   fgets(ip,sizeof(ip),stdin);
	   sendto(sockfd,ip,sizeof(ip),0,(SA*)&servaddr,sizeof(servaddr));
	   len=sizeof(servaddr);
	   recvfrom(sockfd,mac,sizeof(mac),0,(SA*)&servaddr,&len);
	   printf("MAC address is: %s\n",mac);

	   printf("RARP simulation\n");
	   printf("enter mac address :");
	   bzero(mac,sizeof(mac));
	   fgets(mac,sizeof(mac),stdin);
	   sendto(sockfd,mac,sizeof(mac),0,(SA*)&servaddr,len);
	   recvfrom(sockfd,ip,sizeof(ip),0,(SA*)&servaddr,&len);
	   printf("IP address is: %s\n",ip);

	   return 0;
}

FTP simulation to read the file contents

2014-03-18T08:45:00.003-07:00

server.c

#include "stdio.h"
#include "string.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"
#include "netinet/in.h"
#define SA struct sockaddr

int main(int argc,char** argv) {
    int sockfd;
    int n=0,clilen;
    char fname[20],content[2000],ch;
    FILE *fp;
    struct sockaddr_in servaddr,cliaddr;

    if(argc!=2) {
    printf("usage ./server PORT\n");
    return 0;
    }

    //create socket
    sockfd = socket(AF_INET,SOCK_DGRAM,0);

    //fill structure
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(atoi(argv[1]));
    servaddr.sin_addr.s_addr = INADDR_ANY;

    //bind
    bind(sockfd,(SA*)&servaddr,sizeof(servaddr));

    //getting filename from client
    clilen=sizeof(cliaddr);
    recvfrom(sockfd,fname,sizeof(fname),0,(SA*)&cliaddr,&clilen);

    //open the file for reading 
    fp = fopen(fname,"r"); 

    while(1) {
    ch = fgetc(fp);
    if(ch!=EOF) {
        content[n++]=ch;
    }
    else
        break;
    }
    fputs(content,stdout);
    //send the file content to client
    sendto(sockfd,content,sizeof(content),0,(SA*)&cliaddr,sizeof(cliaddr));

    return 0;
}

client.c

#include "stdio.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"
#include "netinet/in.h"
#include "string.h"
#define SA struct sockaddr

int main(int argc,char** argv) {
    int sockfd,len;
    struct sockaddr_in servaddr;
    char fname[20],content[2000];

    if(argc!=3) {
    printf("usage ./client PORT FILENAME\n");
    return 0;
    }
    strcpy(fname,argv[2]);

    //create socket
    sockfd = socket(AF_INET,SOCK_DGRAM,0);

    //fill structure
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(atoi(argv[1]));
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    //send filename
    sendto(sockfd,fname,sizeof(fname),0,(SA*)&servaddr,sizeof(servaddr));

    //receive the file content from server
    len=sizeof(servaddr);
    bzero(content,sizeof(content));
    recvfrom(sockfd,content,sizeof(content),0,NULL,NULL);

    //print the file contents
    printf("contents of the %s:\n\n",fname);
    fputs(content,stdout);

    return 0;
}

UDP echo server, client

2014-03-11T09:56:00.000-07:00

udpserver.c

#include "stdio.h"
#include "stdlib.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"
#include "netinet/in.h"
#include "string.h"
#define SA struct sockaddr
#define MAX 1024

int main(int argc,char** argv) {
    int sockfd,n;
    socklen_t len;
    struct sockaddr_in servaddr,cliaddr;
    char buff[MAX],tmp[MAX];

    //create socket
    sockfd = socket(AF_INET,SOCK_DGRAM,0);
    //fill socket
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(atoi(argv[1]));
    servaddr.sin_addr.s_addr = htonl(INADDR_ANY);

    //bind
    bind(sockfd,(SA*)&servaddr,sizeof(servaddr));

    for(;;) {
    bzero(buff,sizeof(buff));
    len = sizeof(cliaddr);
    n=recvfrom(sockfd,buff,MAX,0,(SA*)&cliaddr,&len);
    strcpy(tmp,buff);
    printf("received : %s",tmp);
    if(n < 6) 
    {
        perror("send message");
        exit(0);
    }
    sendto(sockfd,tmp,MAX,0,(SA*)&cliaddr,len);
    bzero(buff,sizeof(buff));
           }
    close(sockfd);
    return 0;
}

udpclient.c

#include "stdio.h"
#include "stdlib.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"
#include "netinet/in.h"
#include "string.h"
#define SA struct sockaddr
#define MAX 1024

int main(int argc,char** argv) {
    int sockfd,n;
    socklen_t len;
    struct sockaddr_in servaddr;
    char buff[MAX];

    //create socket
    sockfd = socket(AF_INET,SOCK_DGRAM,0);

    //fill struct 
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(atoi(argv[1]));
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    //send to server
    printf("enter message\n");
    for(;;) {
    bzero(buff,sizeof(buff));
    fgets(buff,MAX,stdin);
    len=sizeof(servaddr);
    sendto(sockfd,buff,MAX,0,(SA*)&servaddr,len);
    bzero(buff,sizeof(buff));
    recvfrom(sockfd,buff,MAX,0,(SA*)&servaddr,&len);
    printf("%s",buff);
    }
    close(sockfd);
    return 0;
}

This Week's Experiments

2014-03-08T10:47:00.000-08:00

Experimenting LEOXSYS-nano wifi adapter:

Recently bought this tiny wifi adapter from flipkart.
Making this wifi-adapter able to work is wont be problem under windows. But in LINUX it need some
patience. Linux Kernel doesn't have the supportive drivers to make it workable on linux. Thank god they gave one small disc which contains the drivers for this wifi-adapter.
Inside the disk there are various folders and finally found one Linux folder in it. Make sure you
copy that into your home directory not to any others. (We are going to make it and install it. It needs a folder permission to execute some utility programs) then make it and install it, and it works
just fine in my LinuxMint 14. Soon to register for a wifi connection in my campus :-)

Making Balance enquiry of the usb modem from Terminal

This one is my favourite trick to know the balance amount of my 3g dongle.
All you need is one tiny little program called gammu.

Launch your terminal and pass

$ sudo apt-get install gammu

to install gammu. Then we have to configure the gammu by

$ sudo gammu-config

after the successful configuration of gammu we have to pass the ussd code by sending

$ gammu getussd *123*11#

here *123*11# is the ussd code to check the 3g balance of airtel network.

Very simple way to create a bootable usb disk

This one is a pretty awesome trick. We don't need to search for the unetbootin, startupdisk creator and
other utilities.

There is a built in utility called 'dd' is here to the rescue.

make sure you unmount your usb drive by

$ sudo umount /dev/sdb1

after that we are going to write the iso file to the usb device

$ sudo dd if=/home/mani/Downloads/ubuntu-13.10-desktop-i386.iso of=/dev/sdb
1832960+0 records in
1832960+0 records out

938475520 bytes (938 MB) copied, 338.764 s, 2.8 MB/s

note: in dd command if=*location of the iso file* of=*location of the usb device*

that's it your live usb drive is hot to be served.

for more info about dd in tamil : http://gnutamil.blogspot.in/2014/03/dd-startup-disk-creator-tool.html

Simulation of ARP/RARP

2014-02-27T08:14:00.002-08:00

Here is the core simulation of the ARP(Address Resolution Protocol) and RARP(Reverse Address
Resolution Protocol) ARP used to map the ip address with the corresponding MAC address and
RARP do that in reverse. it maps the MAC with the ip.


#include "stdio.h"
#include "string.h"
int main() {
    char table[3][2][40];
    char ipin[10],macin[30];
    int i,j,found;
    strcpy(table[0][0],"127.0.0.1");
    strcpy(table[0][1],"44:dd:22:11:33");
    strcpy(table[1][0],"10.1.1.8");
    strcpy(table[1][1],"33:aa:fe:4e:2d");
    strcpy(table[2][0],"10.1.8.5");
    strcpy(table[2][1],"23:a3:5d:33:9d");
    
    printf("IP address\t MAC address\n");
    for(i=0;i<3;i++) {
    printf("%s\t %s\n",table[i][0],table[i][1]);
    }

    printf("simulating ARP\n\n");
    printf("enter the IP address\n");
    scanf("%s",&ipin);
    for(i=0;i<3;i++) {
    if(strcmp(ipin,table[i][0])==0) {
        printf("%s mac id is %s\n\n",ipin,table[i][1]);
        found=1;
    }
    }
    if(found!=1) {
    printf("mac not found\n\n");
    }

    printf("simulating RARP\n\n"); 
    printf("enter the MAC address\n");
    scanf("%s",&macin);
    for(i=0;i<3;i++) {
    if(strcmp(macin,table[i][1])==0) {
        printf("%s ip is %s\n",macin,table[i][0]);
        found=1;
    }
    }
    if(found!=1) {
    printf("ip not found\n");
    }

    return 0;
}

Workshop on IBM BIGDATA

2014-02-21T09:01:00.001-08:00

Here is my shell script which i wrote to make the process of installing the IBM biginsight (hadoop) on the lab. My team installed the hadoop using this script for around 70 systems, it saved lots of time for us, and we successfully conducted the workshop on it today.

#!/bin/bash

#generating keygen for the root user with no password
ssh-keygen -f $HOME/.ssh/id_rsa -t rsa -N ''
echo "key generated in $HOME"

#append it to the authorized_keys
cat $HOME/.ssh/id_rsa.pub >> $HOME/.ssh/authorized_keys
echo "appended to authorized_keys"

#create a usergroup

groupadd -g 168 biadmin
echo "group created"

#add a biadmin to the group
useradd -g biadmin -u 168 biadmin
echo "biadmin added to group"

#giving permission for the biadmin to run ssh and scp
chmod o+rx /usr/bin/ssh
chmod g+rx /usr/bin/ssh
chmod u+rx /usr/bin/scp
chmod o+rx /usr/bin/scp
echo "persmissions given"

#to edit the /etc/sudoers file
sed -e 's/# %wheel/%biadmin/g' -e 's/Defaults requiretty/#Defaults requiretty/g' /etc/sudoers >> /etc/sudoers
echo "changed to /etc/sudoers"

#add repo
rm -f /etc/yum.repos.d/*.repo
cp /root/Desktop/hadoop/new.repo /etc/yum.repos.d/
echo "added new.repo"

#preparing to install dependencies
yum clean all

#installing dependencies with(yes to all)
yum -y install tcl expect

#to disable selinux
sed -e 's/selinux=enabled/selinux=disabled/g' /etc/selinux/config >> /etc/selinux/config

#goto the bigdata directory
tar xzvf *.tar.gz
cd /root/Desktop/hadoop/biginsights-quickstart-linux64_b20130821_1818/
bash start.sh

#open firefox with the hyperlink
firefox "http://127.0.0.1:8300/Install/"

#finally append .bashrc file in biadmin
echo export PATH=$PATH:${PIG_HOME}/bin:${FLUME_HOME}/bin:${JAQL_HOME}/bin:${HIVE_HOME}/bin >> .bashrc

Cipher engine in ruby

2014-02-14T09:59:00.001-08:00

Recently i have started to learn ruby because it's the core language for the rails framework.
Here the cipher engine which uses the old caesar cipher algorithm,
i have used file concepts to read and write the both
encrypted and decrypted outputs to files.
We can also use other methods separately,

launch your irb then

load 'encryptor.rb'

make an instance of the Encryptor class by

e = Encryptor.new

to check all the available methods

e.methods

Here is the source

class Encryptor

    def cipher(rotation)
   chars = (' '..'z').to_a 
   rotated_chars = chars.rotate(rotation)
   Hash[chars.zip(rotated_chars)]
    end

    def encrypt_letter(char,rotation)
    cipher_for_rotate = cipher(rotation)
    cipher_for_rotate[char]
    end

    def decrypt_letter(char,rotation)
    decypher_rotate = cipher(-rotation)
    decypher_rotate[char]
    end

    #encryption method

    def encrypt(string,rotation)

    #split the string to letters
    letters = string.split("")

    #encrypt each letters and store it in array
    result = letters.collect do |letter|
        enc_char = encrypt_letter(letter,rotation)
    end

    #join the characters 
    result.join
    end

    #encrypt a file

    def encrypt_file(filename,rotation)
    #1. create the file handle to the input file
    f = File.open(filename, "r")

    #2. read the text of the input file
    text = f.read

    #3 encrypt the text
    encrypted = encrypt(text,rotation)

    #4 create a name for output file
    output = "#{filename}.encrypted"

    #5. create an output file handle
    out = File.open(output,"w")
    
    #6. write out the text
    out.write(encrypted)
    #7. close the file
    f.close
    out.close
    end

    def decrypt(string,rotation)

    #split the string to letters
    letters = string.split("")

    #decrypt each letters
    result = letters.collect do |letter|
        dec_char = decrypt_letter(letter,rotation)
    end
    #join
    result.join
    end

    def decrypt_file(filename,rotation)

    #create filehandler to read
    f = File.open(filename,"r")

    #read the cipher
    cipher = f.read

    #decrypt the cipher
    decrypted_msg = decrypt(cipher,rotation)

    #output filename
    output_filename = filename.gsub("encrypted","decrypted")

    #file handler to write
    out = File.open(output_filename,"w")

    #write contents
    out.write(decrypted_msg)

    #close
    out.close
    end
end

tcp client, server chat simplified

2014-01-16T08:34:00.000-08:00

Here is my simplified version of the tcp client, server chat application

client.c

#include "stdio.h"
#include "stdlib.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"

int main() {
    int sockfd,n;
    char buff[256];
    struct sockaddr_in servaddr;

    //create socket
    sockfd = socket(AF_INET,SOCK_STREAM,0);

    //fill serv struct
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(40402);
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");    //connect with server
    connect(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));

    //read and write with the server
    for(;;) {
    printf("client : ");
    n=0;
    while((buff[n++]=getchar())!='\n');
    write(sockfd,buff,sizeof(buff));
    bzero(buff,sizeof(buff)); //clearing the buffer
    read(sockfd,buff,sizeof(buff));
    printf("server : %s",buff);
    bzero(buff,sizeof(buff));
    }

    //close
    close(sockfd);
}

server.c

#include "stdio.h"
#include "stdlib.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "arpa/inet.h"

int main() {
    int sockfd,connfd,n;
    char buff[256];
    struct sockaddr_in servaddr;

    //create socket
    sockfd = socket(AF_INET,SOCK_STREAM,0);

    //fill server struct
    servaddr.sin_family = AF_INET;
    servaddr.sin_port = htons(40402);
    servaddr.sin_addr.s_addr = inet_addr("127.0.0.1");

    //bind
    bind(sockfd,(struct sockaddr*)&servaddr,sizeof(servaddr));

    //listen for 1 connection
    listen(sockfd,1);
    
    //accept a client
    connfd = accept(sockfd,NULL,NULL);

    //read and write to client
    for(;;)  {
   read(connfd,buff,sizeof(buff));
   printf("client : %s",buff);
   bzero(buff,sizeof(buff));
   printf("server : ");
   n=0;
   while((buff[n++]=getchar())!='\n');
   write(connfd,buff,sizeof(buff));
   bzero(buff,sizeof(buff));
  }

    //close the sockets
    close(connfd);
    close(sockfd);

Executing external programs via c

2014-01-08T07:04:00.001-08:00

import time
print time.ctime()

this snippet will print the system time.
in my networking lab, i used this python snippet to print the system time.
actually i have to write a client, server program in c to achieve this. but i
have found a lazy way.

when mam ask us to show the output i planned to run this python snippet :) (don't tell her);

only problem is i cannot make it as an executable code.

./timecli

this wont work. because only sudoers can use the chmod command to make it executable.

but gcc can make an executables.

so i planned to write a c program to run the python snippet.


#include "stdio.h"
int main()
{
  char cmd[20];
  sprintf(cmd, "python time.py");
  system(cmd);
  return 0;
}

after the compilation using gcc i got a executable to my python snippet.

happy cheating :)

simple tcp echo server

2014-01-06T07:54:00.002-08:00

echoserver.c


//coded by m4n1G
//6-1-2014
//tcp echo server in unix env
#include "stdlib.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "netinet/in.h"
#include "arpa/inet.h"

int main(int argc, char** argv) {
    int server_fd, client_fd;
    char c;
    struct sockaddr_in serv_addr;

    //create a socket
    server_fd = socket(AF_INET,SOCK_STREAM,0);

    //getting ready to bind
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(argv[1]));
    serv_addr.sin_addr.s_addr = INADDR_ANY;
    //bind
    bind(server_fd, (struct sockaddr*) &serv_addr, sizeof(serv_addr));

    //listen to one queue
    listen(server_fd,1);
    
    //accept one client
    client_fd = accept(server_fd, NULL, NULL);

    //read and write until ^D from client
    while(read(client_fd, &c, 1)) { //read from client
    putchar((int)c);
    write(client_fd, &c, 1); // write to client
    }

    //close the connection
    close(client_fd);
    close(server_fd);
    return 0;
}

echoclient.c

//coded my m4n1g
//on 6-1-2014
//tcp echo client

#include "stdio.h"
#include "stdlib.h"
#include "sys/types.h"
#include "sys/socket.h"
#include "netinet/in.h"
#include "arpa/inet.h"

int main(int argc, char** argv) {
    int client_fd;
    struct sockaddr_in serv_addr;
    char c;
    
    //create socket
    client_fd = socket(AF_INET,SOCK_STREAM,0);

    //ready to bind
    serv_addr.sin_family = AF_INET;
    serv_addr.sin_port = htons(atoi(argv[2]));
    serv_addr.sin_addr.s_addr = inet_addr(argv[1]);

    //connect to server
    connect(client_fd, (struct sockaddr*) &serv_addr, sizeof(serv_addr));

    //write to echo server
    while((c=(char) getchar())!=EOF) {
    write(client_fd,&c,1);
    read(client_fd,&c,1);
    putchar((int)c);
    }

    close(client_fd);
    return 0;
}

converting chm to pdf in linux

2013-12-26T23:59:00.002-08:00

There are some paid apps that convert your chm file to pdf in windows.
but in gnu/linux there is an handy tiny little tool called chm2pdf is here to rescue.

installed chm2pdf by

$ sudo apt-get install chm2pdf

after installing it to your box

$ chm2pdf --book my-file.chm [output.pdf]

output.pdf is optional. it will save your pdf document as same as your chm file if you don't give the output name.

it will convert your chm file to structured pdf book.

it may seems simple.. but it saved me from frustration of converting an important document.

long live linux.. :)

JDBC and MySQL

2013-09-13T05:11:00.001-07:00

Here is a quick reference to connect mysql database with java
in linux environment.

INSTALLATION:

Hope jdk, mysql server and client are already installed on your box.
then install the libmysql-java

sudo apt-get install libmysql-java

it will install the connector in your box or download the jar file manually from

http://dev.mysql.com/downloads/connector/j/

if mysql-connector-java.jar is located in the /usr/share/java
then set the classpath

CLASSPATH=$CLASSPATH:/usr/share/java/mysql-connector-java.jar
export CLASSPATH

to make this CLASSPATH persistent add them to .bashrc file

now check with

echo $CLASSPATH

it will show similar to this :/usr/share/java/mysql-connector-java.jar

MYSQL PART

Create a user with all privileges by doing these things

at the mysql> prompt

USE mysql;

create a user mani with all privileges by

create user 'mani'@'localhost' identified by 'mani';
grant select, insert, update, delete, create, drop, references,
execute on *.* to 'mani'@'mani';

then quit the mysql by

exit;

now login with

mysql -h 127.0.0.1 -u mani -p

it will prompt for the password and enter the password we created. that is same as user

now start to create a table with all the things you needed.

JAVA PART:

database url is jdbc:mysql://localhost/dbname

dbname is the database name we want to connect.

//java program to connect mysql and query the student table
import java.sql.Connection;
import java.sql.Statement;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;

public class Student {
 //database url
 static final String DB_URL="jdbc:mysql://localhost/test";
 
 //main method
 public static void main(String[] args) {
  Connection connection = null; //connection manage
  Statement statement = null;
  ResultSet resultSet = null;
  
  try {
  //connecting with db
  connection = DriverManager.getConnection(DB_URL,"mani","mani");
  
  //statement 
  statement = connection.createStatement();
  //execute statement
  resultSet = statement.executeQuery(
   "SELECT name,age,grade FROM student");
 
  //process query results
  ResultSetMetaData metaData = resultSet.getMetaData();
  int numColumns = metaData.getColumnCount();
  System.out.println("Student information table: ");
  
  for(int i=1;i<=numColumns;i++) 
   System.out.printf("%-8s\t",metaData.getColumnName(i));
  System.out.println();
  System.out.println();
  while(resultSet.next())
  {
   for(int i=1;i<=numColumns;i++)
    System.out.printf("%-8s\t",resultSet.getObject(i));
   System.out.println();
  } //end while
  } //end try
  catch(SQLException sqlexception) {
   sqlexception.printStackTrace();
  } //end catch
  
  finally
  {
   try
   {
    resultSet.close();
    statement.close();
    connection.close();
   } catch(Exception exception) {
    exception.printStackTrace();
   } //end catch
  } //end finally
 } //end main
} //end class

that's it happy hacking..

Bulk rename in bash

2013-09-13T04:37:00.001-07:00

here i found a very simple command flow to rename
the files in a folder by sequence order

i have list of *.png file with different names for example

Monsters-University-Icon-5.png
Monsters-University-James-P-Sullivan-Icon-2.png
.
.

i need to rename in to

Mon01.png
Mon02.png
.
.

here is a solutions

#!/bin/bash
a=1
for i in *.png; do
new=$(printf "Mon%02d" ${a})
mv ${i} ${new}
let a=a+1
done

it will do the magic..

Sublime and java

2013-08-25T09:58:00.000-07:00

SublimeText is an cross platform editor, written in python. it provides a lots of good stuffs. i never expect these much from this tiny editor.

i have made some tweak to compile and run my java code inside the sublime editor.

just goto Preferences -> Browse packages

now you'll see a lots of folders. now goto java folder and
select JavaC.sublime-build and open it.

now replace the contents with the below script

{
    "cmd": ["bash", "-c", "javac ${file} && java ${file_base_name}"],
    "file_regex": "^(...*?):([0-9]*):?([0-9]*)",
    "selector": "source.java"
}

now done.

write your java code and ctrl+b to compile and run you code.

happy coding :)

Free SMS from your terminal REBOOT

2013-06-10T10:35:00.000-07:00

i have gained some (litlte)knowledge with python..

i'm on my semester holidays.. so i had some time to dance with that snake.
since way2sms perl script is not working to send sms, because they
rapidly modifying there site.

so i have planned to test my skills with python

by using only mechanize module i have done this.

i have written this code which automate the processes of sending message from indyarocks.

functions much similar the script i previously posted.

read the README file in my repo.

before that install mechanize module by

sudo apt-get install python-mechanize

or install it from software center.

fork it if you interested to improve that script

at first you have to register with indyarocks to send sms

then fill your username and password in it.

then start texting to your friends..

i have hosted the source code on github.

https://github.com/manimaran990/indsms

#!/usr/bin/python
import mechanize
import cookielib
import sys
br=mechanize.Browser()
cj=cookielib.LWPCookieJar()
br.set_cookiejar(cj)
br.set_handle_robots(False)
br.addheaders=[('User-agent','Mozilla/5.0 (X11; U; Linux i686; en-US, rv:1.9.01) Gecko/2008071615 Fedora/16.0.1-1.fc9 Firefox/17=18.0.1')]

def gettxt():
    print "enter your message : "
    txt=""
    while True:
        line=str(raw_input())
        if "$" in line:
            break
        else:
            txt+=line+'\n'
    return txt

def loginsite():
    print '>>> pls wait...'
    br.open('http://indyarocks.com/login')
    br.select_form(nr=0)
    br.form['LoginForm[username]']=your user name
    br.form['LoginForm[password]']=your password
    br.submit()
    if 'profile' in br.geturl():
        print 'login successfully'
    else:
        print 'failed to login'

def sendsms(mno,msg):
    print '>>> sending...'
    br.open('http://www.indyarocks.com/send-free-sms')
    br.select_form(nr=1)
    br.form['FreeSms[mobile]']=mno
    br.form['FreeSms[post_message]']=msg
    br.submit()
    if 'login' in br.geturl():
        print 'failed'
    else:
        print '>>> sent'

def groupsms(book,txt):
    loginsite()
    f=open(book)
    for line in f.readlines():
        mno=line.split()[1]
        print 'sending to : '+line.split()[0]
        sendsms(mno,txt)
    print 'done'

def logoutsite():
    br.open('http://www.indyarocks.com/logout')
    print 'logout successfully'
    sys.exit()


def main():
    if len(sys.argv[:])==1:
            print '''
************************************
usage :

./indsms.py mobileno
or
./indsms.py file.txt

press '$' to terminate the input message
************************************
'''
            sys.exit()
    if '.txt' in sys.argv[1]:
        msg=gettxt()
        groupsms(sys.argv[1],msg)
        logoutsite()
    else:
        msg=gettxt()
        loginsite()
        sendsms(sys.argv[1],msg)
        logoutsite()

if __name__=='__main__':
    try:
        main()
    except KeyboardInterrupt:
        print 'aborted by you'

if you have any queries feel free to ask me..

awesome vi editor

2013-04-16T09:43:00.002-07:00

"vi" is not an ordinary editor. it is a popular among programmers.
in our lab most of them struggle to do copy, paste like simple things in it..
it's hard to get for the first time, but later only we can realize how
awesome the "vi" is.
my fav. commands:
vi has two modes:
1. command mode (press esc)
in command mode our cursor will point at the bottom followed by :
2. edit mode (press i)
normal edit mode we can type whatever we want

in command mode:
vi filename.cc -> to create a new file
h -> left
j -> down
k -> up
l -> right
:w -> to save
:q -> to quit
:q! -> quit without saving
dw -> delete a single word from cursor
dd -> delete whole line
:!g++ file.cc -o file -> this one will compile our code without closing our file. actual syntax is :!command
where we can execute terminal commands in it. like ls, date, cal etc.

:set autoindent -> automatically indent our source code
:set number -> set line numbers
:set hlsearch -> enable highlight search

உபுண்டுவில் ஓபன் DNS அமைத்தல்

2013-03-28T08:54:00.000-07:00

DNS(Domain Name System) என்றால் என்ன?

ipமுகவரிகள் மூலம் தான் நெட்வர்க்கில் உள்ள கணினிகள் மற்றதை தேடி அதனை தொடர்பு

கொள்கின்றன. ஆனால் நம்மால் பல ipமுகவரிகளை நினைவில் வைத்துக்கொள்வது கடினம். உதரணாமாக dns இல்லை என்றால் நீங்கள் கூகிலை அடைய ஒவ்வொரு முறையும் 74.125.135.105 என்ற ip கொடுக்க வேண்டும். dns இந்த வேலையை சுலபமாக்குகிறது. ஒவ்வொரு முறையும் இந்த ip முகவரிஐ கொடுப்பதற்கு பதில் அதன் domain nameஐ கொடுத்தால் dns அதற்கு இணையான ipயை கண்டுபிடித்து அதனுடன் இணைக்கிறது.

rDNS(reverseDNS) ipஐ டொமைன் nameஆக மாற்றித்தருகிறது.

எதற்காக openDNS?

நம் ISP தரும் dns ஐதான் பெரும்பாலும் பயன்படுத்துவோம். நமது விருப்பத்திற்கு ஏற்ப இதனை மாற்றிக்கொள்ள முடியும். ஓபன்dns என்பது இலவசமாக கிடைக்கும் ஒரு சேவை.

இது நமது ஐ எஸ்பி தரும் dnsவிட பல விதங்களில் நமக்கு பயன் அளிக்கும்.

உதாரணமாக ஐ எஸ் பி dnsவிட வேகமாக தளங்களை இணைக்கும், தவறாக

அடிக்கும்(typos) தளங்களை திருத்தும், தேவையற்ற அபாயகரமான தளங்களை(phishing, adult sites) தடுக்கும்,

இதைனை அமைப்பதற்கு எந்த மென்பொருளும் நாம் தரவிறக்க தேவையில்லை. இதை அமைப்பது மிக சுலபம்.

உபுண்டுவில் இதனை அமைப்பதற்கு

network-manager சென்று அதில் உள்ள edit connection என்பதை கொடுக்கவும்.

அதனை தேர்வு செய்து பிறகு எடிட் என்பதை அழுத்தவும்.

அதில் வரும் மூன்றாவது டேபினை அழுத்தவும். methodல் உள்ள Automatic(DHCP) address only தேர்வு செய்யவும்.

பிறகு DNS servers: 208.67.220.220, 208.67.222.222 என்பதை தரவும். அவ்வளவு தான்.

இது சரியாக வேலை செய்கிறதா என்று காண

welcome.opendns.comசெல்லவும்.

இதற்கு பதில் 8.8.8.8, 8.8.4.4 என்ற கூகுளின் பப்ளிக் dns ஐயும் தரலாம். ஆனால் ஒபன்dns தரும் செவைகளை விட குறைவுதான்.

March monthly meet

2013-03-25T10:44:00.000-07:00

Date: 24-11-2013

Time: 10 am to 12

Location: Kailasanathar Temple, KPM

Today we had a meet at kailasanathar temple,
Since last few months we didn't have any activity. so
we discussed about the current status of our lug community and how to
refine this problem.
some old members also participated in the meet and suggested some
good ideas.

And we finally come to a conclusion to do some frequent activities

like conducting hackathon, monthly irc meet, contributing in
writing articles, making video tutorials, and much more.

Also we made a decision to conduct lug meet at every month fourth
sunday.

i hope everything should be happen like we talked.

Balaji G, Selvamani S, Dilliganesh K, Srinivasan T,
Rajkumar K, Dhanasekar T, Manimaran R and myself participated
in the meet.