Category: Open source

how to check programs installation path in linux

There are many linux distributions like fedora, redhat, centos. Each has different program installation path. Using following commands you can check programs installation path in linux

how to check programs installation path in linux

Use following commands:

</pre>
[root@localhost ]# which php
/usr/bin/php
[root@localhost ]# which ruby
/usr/bin/ruby
[root@localhost ]# php --version
PHP 5.2.9 (cli) (built: Apr 17 2009 03:42:25)
Copyright (c) 1997-2009 The PHP Group
Zend Engine v2.2.0, Copyright (c) 1998-2009 Zend Technologies
with eAccelerator v0.9.5.2, Copyright (c) 2004-2006 eAccelerator, by eAccelerator
[root@localhost ]# ruby --version
ruby 1.8.6 (2008-08-11 patchlevel 287) [i386-linux]
[root@localhost Desktop]#

Solved: Access denied with code 400 (phase 2).

When I restarted my apache server. I am using the fedora 9 here.

I did not get my default page opened in browser.
When I opened the apache error log file. I saw following error.

ModSecurity: Access denied with code 400 (phase 2). Pattern match “%0[ad]” at REQUEST_HEADERS:Cookie. [id “950910”] [msg “HTTP Response Splitting Attack. Matched signature <%0a>”] [severity “ALERT”] [hostname “localhost”] [uri “/”] [unique_id “SuWoGH8AAAEAAFF3rKEAAAAA”]

I after doing some R&D but I did not got any perfect soluction.
Then I cleared the whole browser cookies. That solves my problem.

solution – clear the browser cookies…

solved: [warn] _default_ VirtualHost overlap on port 80, the first has precedence

Here I am using the Fedora 9 for this example. I solved the issue of _default_ VirtualHost overlap on port 80 warning in linux

If you want to host many sites on one computer or machine.
I added following lines to httpd.conf file(end of file).

[viral-lock message=”Solution code is Hidden! It’s Visible for Users who Liked/Shared This article on Facebook or Twitter or Google+. Like or Tweet this article to reveal the content.”]

<VirtualHost  *:80>

Options +FollowSymLinks
ServerName example1.com
DocumentRoot /var/www/html/example1

VirtualHost>

<VirtualHost  *:80>

Options +FollowSymLinks
ServerName example2.com
DocumentRoot /var/www/html/example2

</ VirtualHost>

[/viral-lock]

When I restarted the apache server using following command.
#su
#ROOT_PASSWORD
#/etc/init.d/httpd restart

I got the following error;
[warn] _default_ VirtualHost overlap on port 80, the first has precedence

Again I opend the httpd.conf tile and I read following lines;
#
# Use name-based virtual hosting.
#
#NameVirtualHost *:80

# NOTE: NameVirtualHost cannot be used without a port specifier
# (e.g. :80) if mod_ssl is being used, due to the nature of the
# SSL protocol.
#

Than only I uncommented following line and restarted the Server.

NameVirtualHost *:80

My promlem get solved.

How to Add or Remove the javascript file using javascript function

We can use following functions for adding the Javascript file dynamically.

function AddJsFile(file) {
var script  = document.createElement('script');
script.src  = file;
script.type = 'text/javascript';
script.defer = true;

document.getElementsByTagName('head').item(0).appendChild(script);
}

Or We can use this also, both will work:
function AddJsFile(file)
{
document.write('');
}

We can use following functions for adding the CSS file dynamically.


function AddCssFile(file) {
var stylesheet  = document.createElement('link');
stylesheet.href  = file;
stylesheet.type = 'text/css';
stylesheet.defer = true;

document.getElementsByTagName('head').item(0).appendChild(stylesheet);
}

Or We can use this also, both will work:

function AddCssFile(file)
{
document.write('');
}

We can use the following code for remving the JS the files.


function RemoveJsFile(file) {
var alljs = document.getElementsByTagName("js")
for (var i = alljs.length; i >= 0; i--) {
if (alljs[i] && alljs[i].getAttribute("src")!= null && alljs[i].getAttribute("src").indexOf(file)!=-1)

alljs[i].parentNode.removeChild(alljs[i])
}

}

We can use the following code for remving the CSS the files.

function RemoveCssFile(file) {
var allcss = document.getElementsByTagName("css")
for (var i = alljs.length; i >= 0; i--) {
if (allcss[i] && allcss[i].getAttribute("href")!= null && allcss[i].getAttribute("href").indexOf(file)!=-1)

allcss[i].parentNode.removeChild(allcss[i])
}

}

get time difference in minutes in javascript

we created java-script function named “getTheDiffTime” using that function you will be able to fetch the time difference in various format.

javascript get time difference in minutes


function getTheDiffTime(dateone, datetwo,format){
//format = "Days", Hours, Minutes, Seconds
if(dateone > datetwo) {
var seconds = dateone.getTime() - datetwo.getTime();
} else {
var seconds = datetwo.getTime() - dateone.getTime();
}
var second = 1000, minute = 60 * second, hour = 60 * minute, day = 24 * hour;
if(format=="Days"){
var rformat = Math.floor(seconds / day);
seconds -= rformat * day;
//alert("days: "+rformat);
}else if(format=="Hours"){
// find the hours
rformat = translate(seconds / hour);
//alert("hours: "+rformat);
}else if (format=="Minutes"){
//find the mintues
rformat= translate(seconds / minute);
//alert("minutes: "+ rformat);
}else if(format=="Seconds"){
//find the seconds
rformat = translate(seconds / second);
//alert("seconds: "+rformat);
}

return rformat
//alert(rformat);

}

How to use this function here I am giving you the one good example.

I am going to get the current months minutes using this function.


//for calculating the current month in mintue -script
currentMonth = new Date();
plus_oneMonth = new Date();
plus_oneMonth.setMonth(plus_oneMonth.getMonth()+1);

getTheDiffTime(plus_oneMonth,currentMonth,"Minutes");

You will get return the minutes.

How to use the killall command on linux

Killall command is very useful in linux. You can stop or kill the all same processes.

killall command can used in Linux and Unix OS.

killall – kill processes by name

You can find the process name by using this command:
#ps -ef|grep firefox

for kill the process
#su
#ROOT_PASSOWRD
#killall firefox

Solved issue -Directory index forbidden by Options directive:

I want to change the default location of Apache folder which is (var/www/html).
I am using the Fedora as OS and apache 2 here. you can use following code with any linux box like centos or ubuntu. Here we solved the issue of directory.

When I inserted the following code in bottom of the httpd.conf file.
<VirtualHost *:80>
Options +FollowSymLinks
ServerAdmin siwan@yahoo.co.in
DocumentRoot /var/www/html/testfolder
ErrorLog logs/error_log_net
TransferLog logs/access_log_net
</VirtualHost>

When tried the http://localhost/ in browser, I got the default browser page.
Then I tried to look my apache error using following command:
#[root@localhost ]# tail -f /var/log/httpd/error_log

In apache error log I got following error.
[Wed Oct 07 15:59:50 2008] [error] [client 127.0.0.1] Directory index forbidden by Options directive: /var/www/html/testfolder/

I changed the AllowOverride option but nothing is happens. Then I read the welcome page text
“To prevent this page from ever being used, follow the instructions in the file /etc/httpd/conf.d/welcome.conf.”
I opend the welcome.conf file.

I found following lines in welcome.conf file.
<LocationMatch “^/+$”>
Options -Indexes
ErrorDocument 403 /error/noindex.html
LocationMatch>

I changed that to as follows:

[viral-lock message=”Solution code is Hidden! It’s Visible for Users who Liked/Shared This article on Facebook or Twitter or Google+. Like or Tweet this article to reveal the content.”]

<LocationMatch “^/+$”>
Options Indexes
ErrorDocument 403 /error/noindex.html
</LocationMatch>

[/viral-lock]

That solve my problem. Some time your selinux will cause the issue so you need to deactivate the selinux.
Some time File permission will also cause the issue.
You can change the file permission using following command, go to that directory and run following command.
#chmod 777 *

You can use above commands on any linux box. Ubuntu, centos, redhat or on fedora box.. still solution will be same.

clean url with html file

We have site in plain html file and some time we want to use clean URLs or Pretty URLs for our site.
Clean URLs are in demand becasue of Seach Engine Optimiztion.

You can achive the Clean URLs. With not doing rework of building site.

Requirement:
Apache Server.
mod_rewrite engine need to on.

Create .htaccess file
and copy paste the following lines

Options +FollowSymLinks
RewriteEngine On

RewriteCond %{SCRIPT_FILENAME} !-d
RewriteCond %{SCRIPT_FILENAME} !-f

#code for About us Page
RewriteRule ^about-us(\d+)*$ ./about.html$1

Put this file into your root folder.

What this will do?

For example I want

www.example.com/about.html to look like www.example.com/about-us/

How to use juggernaut in Rails project

Juggernaut is the Rails plugin for sending and receiving data in different thread. It gives you real time connection to server and you can implement different ideas work or fulfil your requirement.

Juggernaut uses the eventmachine as a server.

So install the supported gem first.

#gem install json

#gem install eventmachine

#gem install juggernaut

Juggernaut is aims to revolutionize your Rails app by letting the server initiate a connection and push data to the client.

Juggernaut is used for speciallycreating Chat application.

If you want to full details about Juggernaut then go to http://juggernaut.rubyforge.org/

First install the juggernaut to your application using this command.
ruby script/plugin install git://github.com/maccman/juggernaut_plugin.git

install the gem : gem install juggernaut

Configure the gem: juggernaut –g juggernaut.yml

Start the Juggernaut server: juggernaut -c juggernaut.yml

(This is not rails server or mongrel server)

In your controller you can use this method to send data to Juggernaut server

Juggernaut.send_to_all(“alert(‘hi from juggernaut’)”)

If you want customize the Juggernaut methods or add new methods then open file:

/vender/plugin/juggernaut_plugin/lib/juggernaut.rb

Add your methods there and use in your projects.

link_to with image_tag in Rails

This is very basic form tag in rails. but some time you get confused about using this tag.

How to displays a image inside link_to instead of text?

Here is answer:
<%= link_to image_tag(“/images/submit.jpg”, :border=>0), :action => ‘create’ %>

Section Option:

<%= link_to image_tag(“/images/submit.jpg”, :border=>0,:class=>’sub20′), :url =>{:controller=> ‘user’,:action=>’create’}  %>