Perl File Example

The aim of this simple example is to show how to read and write a file in Perl. This will read from a file trim the white space at the start and end and append the result to another file.

First lets have a look at the example. It's really self explanatory.

1. open (readfile, '<input.csv') or die "could not open file to read"; 2. open (writefile, '>>output.csv') or die "could not open file to write"; 3. while(<readfile>){ 4. #read from 'readfile', trim and write to 'writefile' 5. $_ =~ s/(^ *| *$)//gi ; 6. print writefile $_; 7. } 8. close(readfile); 9. close(sritefile); Hide line numbers

Perl Database Example - ODBC DSN

This article has moved back to Code Diaries.

You can read this at Perl Database Example - ODBC DSN

How to Write a Simple Web and Image Crawler in Perl

This article has moved back to Code Diaries.

You can read it at How to Write a Simple Web and Image Crawler in Perl

Perl Socket Example

The aim of this tutorial is to show how to read and write a socket in Perl. We will open a socket to a website, write the request headers, read the response and write the response to the console. You do not need any prior HTTP 1.x knowledge.

First lets have a look at the example. It's really self explanatory.

1. use IO::Socket; 2. 3. my $sock = new IO::Socket::INET (PeerAddr => 'localhost', 4. PeerPort => 8080, 5. Proto => 'tcp'); 6. die "could not create socket: $!\n" unless $sock; 7. 8. printf $sock ("GET / HTTP/1.0\n"); 9. printf $sock ("Host: localhost\n"); 10. printf $sock ("Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8"); 11. printf $sock ("User-Agent: Mozilla/5\n"); 12. printf $sock ("Connection: keepalive\n"); 13. printf $sock ("\n\n"); 14. 15. while (<$sock>) { 16. if($_=~ m/validate_response/i) { 17. last; 18. } 19. else{ 20. print $_; 21. } 22. } Hide line numbers

Line 3 We open the socket to localhost on port 8080. This is where my server tomcat ususally runs. But you can change this to anything

Lines 8-13 Here we write out the reust HEADER to the webserver. Just remember if you change your host from 'localhost' to something else, you need to change line 9 to reflect that too.

Lines 15-22 Read the response from the webserver and write it to the screen.