Perl piped log script only running every 2 hits

Question

I am using this script for a piped log setup in Apache 2:

#!/usr/local/bin/perl

$|=1; # Use unbuffered output
while (<STDIN>)
{
   if (<STDIN> =~ m/(.php|.html|.htm|.dhtml|.cpp|.h|.c|.txt|.pdf|.pl)$/)
      {system("beep");}
}

I am sending in the directive %f to give it the filename. As you can tell, it checks to see if the requested filename is a content file. If so, it tells the system to beep. For some reason however, the server only beeps every two times a content page is accessed. Does anyone know why this might happen?

I'm pretty sure it has to do with the way I'm using <STDIN>, because this is my first Perl script.

Answer 1

You read the first line with the while(), then you read another in the if().

Change the 'if' to: if($_ =~ ...)

Answer 2

Try:

while ( <> ) {
  system("beep") if /php|pl.../;
}