string path = "the path to your file";
string fileName = "Add your file name";
string contentType= "Add your file content type. ex: for text file it is 'text/plain'";
string contentLength = "add string presentation of your file size in bytes";

response.Clear();
response.ClearHeaders();
response.AddHeader("Content-Disposition", "attachment; filename=" + fileName);
response.AddHeader("Content-Length", contentLength);
response.ContentType = contentType;
FileStream f = new FileStream(path, FileMode.Open);
byte[] buffer = new byte[8 * 1024];
int len;
while ((len = f.Read(buffer, 0, buffer.Length)) > 0)
{
    response.OutputStream.Write(buffer, 0, len);
}
response.OutputStream.Flush();
response.OutputStream.Close();
response.Flush();
response.Close();
response.End();

We are introducing first ever multilingual Web Search Engine Pipilika in Bangladesh both in Bengali and English. This free web service provides search results on nationwide news and business  information  to  the  people  and  for  the  people.  The  focused  crawler  crawls  news data  from  the  popular  daily  newspapers  and  it  indexes  them  in  our  indexer.  Hence  the search  engine  is  able  to  supply  up-to-date  news,  articles,  reviews  etc.  of  different  news portals. Renowned Search Engines have not paid much attention on Bengali search. So, we tried to give more emphasize on Bengali news analysis and searching.

More Screenshots:

The table

Now we can get the available dates group by excluding time by using the following query

SELECT date_format(`DATE`, '%Y-%m-%d') as date FROM `student_admission_info`

                    where `DATE` IS NOT NULL

                    group by date_format(`DATE`, '%Y-%m-%d')

                    order by date_format(`DATE`, '%Y-%m-%d') desc

Manual for mysql date_format function is here

http://dev.mysql.com/doc/refman/5.1/en/date-and-time-functions.html#function_date-format

Ubuntu by default have the python-notify installed. If don’t install it using

sudo apt-get install python-notify

Sample notification program using python for notifyOSD

Now you open gedit or any other text editor, paste the following code and save it as notify.py

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

if __name__ == "__main__":
	if not pynotify.init("icon-summary-body"):
		sys.exit(1)

	n = pynotify.Notification(
	    "Burhan Uddin",
	    "What is life? Full of of care? We have no time to stand or stare!",
	    "notification-message-im")
	n.show()

Now run this py file using terminal

python notify.py

And see the output

First tokenize the "কકى" strings with ";" and then strip out "&#", the integer numbers you are getting is the decimal values of hex. Convert these string to integer and then add with '\u0000' now type cast it to char
and you will get the hex ie unicode character

int codePoint = 2537;
char c = (char) ('\u0000' + codePoint);

Yesterday, I had to do the same job again. This time I took up regular expression to parse the html <a tags followed by href attribute to extract the links.

Regular expressions can be difficult to understand if written at once, so I am going to write it in easy way first, then i ll make it complex to support variations in page links.

1. Parsing page title using regular expression

First i parsed html titles from pages with this regex

<title>(.*?)</title>

This is a very simple form of regular expression. Which says to find the string <title> then "." is for any charecter. * means the previous character can repeat 0 or more times. The ? sign means that first to look for 0 matches. </title> means that there must be the string</title> after. brackets defines a group of charecters that is any charecter happenning 0 or more times.

1.1 Match anything between <a> and </a>

<a>(*.?)</a>

Similarly why not try this for "a" tag ??

1.2 Match anything in a tag

What we had done in the previous step is just to match the title of a tag

<a href="http://www.dscripts.net">DSCRIPTS</a> would only return "DSCRIPTS"

But to strip the real url must access the attributes of a tag. So get in little bit deeper

<a(.*?)</a>

This would return anything between <a and </a> But we actually need anything between <a href write

1.3 Match <a href

<a href(.*?)</a>

This would match ="http://www.dscripts.net">DSCRIPTS

<a href=(.*?)</a>

This would match "http://www.dscripts.net">DSCRIPTS

1.4 Match both href tag and link title

So far we had the tail >DSCRIPTS. We need to remove it. We can do this by declaring another group. First one will match href attribute and second one will match the title

<a href=(.*?)>(.*?)</a>

Here the first group will match the link "http://www.dscripts.net" and the second one will match DSCRIPTS

1.5 Match a href between quotes

So far this examples we didn't search the quotes arround href attribute so it returned "http://www.dscripts.net" not http://www.dscripts.net

Well this part is little tricy, lets first say whats we are gonna do.

We need to match for one quote " after href= then followed by any charecter  and then another " ??

href =\"(.*?)\"

Note: quotes required to escaped with backslash \

Not exactly if we say any character then it will also match " so it will never catch the trailing " on that tag. Rather catch the last quote in last a tag in document

<a href="link1.html">LINK 1</a>

<a href="link2.html">LINK 2</a>

<a href="link3.html " >LINK 3</a>

So this will return the yellow marked result. Do you really want that :p

Surely ans is no.

So in our expression we must say not to have any " between preceding and trailing quotes. Right ?

Here we will write one expression that will define to match any charecters exlcules a set of charecters we set

[^\"]

This defines a set of charecter which is true for anything else ". and we can have this any number of time

[^\"]

So we rewrite our expression as follow

<a href=\"([^\"]*)\">(.*?)</a>

1.6 What if the a tag has some whitespaces arround??

Here we have used a very neat html here. it will match anything like

<a href="http://www.yoursite1.com">Site 1</a>

<a href="http://www.yoursite2.com">Site 2</a>

anything similar.

But what if ??

<a href = "http://www.yoursite.com" >Site</a>

or

<a     href    =   "http://www.yoursite.com"    >Site</a>

This not gonna match

so we need to modify our expression to allow this whitespaces

whitespaces are denoted as \s in regular expression.

So we modify our expression as

<a \s*?href\s*=\s*\"([^\"]*)\"\s*>(.*?)</a>

So now it can match these criterias.

1.7 What if the tag has some more attribute.

Sure you cant say that a tag will have only href attribute! What if it is anything like these below

<a class="my-class" href="http://www.dscirpt.net">DSCRIPTS</a>

<a id="HOME" class="my-class" href="http://www.dscirpt.net">DSCRIPTS</a>

<a class="my-class" href="http://www.dscirpt.net" id="HOME" >DSCRIPTS</a>

<a href="http://www.dscirpt.net" id="HOME" class="my-class" >DSCRIPTS</a>

In most case you are going to face hyperlinks like this.

So we must also think about the other attributes before and after href attribute. They can either many or none in either side. :s

So on both side of href we can have any characters except > what means the end of start tag and start to link title

<a\s[^>]*href\s*=\s*\"([^\"]*)\"[^>]*>(.*?)</a>

As you can see I added [^>]* on both sides of href tag to say we can have anything else > which is the end of start tag. So by using this we are catching all attributes wether they exists or not on both side of href attribute

\s is an optional replacement of " " (space) which defines there must be one white space immediately after <a

Now take a look at the final expression once again…

<a            Must have <a
\s            Must have one whitespace
[^>]*         Can have anything except > and can happen 0 or more times (Any attribute)
href          Must have href
\s*           May have whitespace for 0 or more times
=             Must have =
\s*           May have whitespace for 0 or more times
\"            Must have one "
  (             Start of first group
    [^\"]*        Can have any charecter except " and can repeat 0 or more times
  )             End of first group
\"            Must have one "
[^>]*         Can have anything except > and can happen 0 or more times (Any attribute)
>             Must have >
  (             Start of second group
    .*?           can have any charecter 0 or more times
  )             End of second group
</a>          Must have end tag

Drawbacks

Although I tried to make it effecient as much as possible, but yet its already have so many drawbacks. One of the most important thing is not to detect href with single quote

<a href='http://www.dscripts.net'>DSCRIPTS</a>

It also case sensetive meaning it can only detect lowercase tags not

<A HREF='http://www.dscripts.net'>DSCRIPTS</a>

I detected end of attributes with > but what about this

<a class="broker-class" title="this will break > regular expression" href='http://www.dscripts.net'>DSCRIPTS</a>

These are still not clear to me. I hope to update this expression as much as possible

Regular Expressions in Java

Now we have the expression now we are going to implement this on java.

To use regular expession in java we mainly use to classes Pattern and Matcher from java.util.regex package.

Pattern is responsible for creating an compiled object of regula expression from a string. And matcher is responsible for matching it with input data.

Note : In regular expressions we used backslash for special purposes. When writting regular expression as java string we need to escape this backslashes with another backslash.

Here is simple parser class used to parse links from web page, I used an hashmap instead of array because i do not need to have the repeative links from the page. I also used the hashmap to count the occurences of links.

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */
package crawler;

import java.util.HashMap;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 *
 * @author burhan
 */
public class parser {
    // regular expression for parsing links
    private String regex_links = "<a\\s[^>]*href\\s*=\\s*[\"\']?([^\"\' ]*)[\"\']?[^>]*>(.*)</a>";
    //hash map to store the links
    private HashMap<String, Integer> link_map;

    public void parse(String data) {
        // create pattern object
        Pattern p = Pattern.compile(regex_links);
        // create mather object
        Matcher m = p.matcher(data);

        String link = null;
        link_map = new HashMap();

        // search the input strings
        while (m.find()) {
            // find links which is in group 1
            link = m.group(1);
           // check if hasmap already contains the link or not
            if(link_map.containsKey(link))
                link_map.put(link, link_map.get(link)+1); // set count +1
            else
                link_map.put(link, 1); // set count 1
        }
    }

   //returns the links
    public HashMap<String, Integer> getLinks(){
        return link_map;
    }

}

So open up the file with visudo command. You must use this command to edit this

burhan@burhan-desktop:$ sudo visudo

If you want to set user permission like root user add it below

# User privilege specification
root    ALL=(ALL) ALL

like username ALL=(ALL) ALL

This will allow user do anything like root

Here I would like to add user to sudo list so that he make sudo command with password promt.

I want to add all users of nutch group in sudo users list. So i changed it to something like this

# Allow members of group sudo to execute any command after they have
# provided their password
# (Note that later entries override this, so you might need to move
# it further down)
%sudo ALL=(ALL) ALL
%nutch ALL=(ALL) ALL

Here is an example

I want to create a user named "nutch" with a new "nutch" user group. Here is how I did it.

First create the user group

burhan@burhan-desktop:/usr/share$ sudo addgroup nutch
Adding group `nutch' (GID 1002) ...
Done.

Now create the user account within the user group

burhan@burhan-desktop:/usr/share$ sudo adduser nutch --ingroup nutch
Adding user `nutch' ...
Adding new user `nutch' (1002) with group `nutch' ...
Creating home directory `/home/nutch' ...
Copying files from `/etc/skel' ...
Enter new UNIX password:
Retype new UNIX password:
passwd: password updated successfully
Changing the user information for nutch
Enter the new value, or press ENTER for the default
	Full Name []: NUTCH
	Room Number []: NUTCH
	Work Phone []: NUTCH
	Home Phone []: NUTCH
	Other []: NUTCH
Is the information correct? [Y/n] y
burhan@burhan-desktop:/usr/share$ su nutch
Password:
Added user nutch.

nutch@burhan-desktop:/usr/share$

Now open the terminal and enter the command

sudo passwd

This will let you to change root account password as you used sudo! Now enter the new password and confirm. Yes! You are done

In linux it is set using crontab command. If you have cpanel then it will also provide you an user interface to manage your cron jobs. Most paid hosting support these. But in most cases it is not available on free hosts. But still if you need this, to maintain a regular check or execution of something and you dont have this feature provided by your host, you can still manage to do so…

You can be cron less but don’t get hopeless!!!

Fortunately some providers are providing free service of cron jobs on internet. Though they have lots of limitations on time and how often you can run cron, but still you can manage to do so Here is two I have found by googling..

1. http://www.setcronjob.com/

This will allow you to run free cron jobs at minimum of 10 minutes interval. But they have set a resource point for each time you run the cron. Resource point for each cron depends on how often you run cron. When you are out of resource point you cannot add any more cron jobs to your account.

2. http://www.cronless.com

This will allow you run as many cron jobs as you want but not more than twice a day. That is minimum interval of running your cron jobs should be atleast 12 hours