Extract all URL from a file or website

Frequently one may want to extract all the URL in a webpage.  There are many ways to do this.  Below is an example:

#!/usr/bin/env bash

gawk 'BEGIN{

RS=""

IGNORECASE=1

}

{

  for(o=1;o<=NF;o++){

    if ( $o ~ /href/){

      gsub(/.*href=\042/,"",$o)

      gsub(/\042.*/,"",$o)

      print $(o)

    }

  }

}' 

Pipe the webpage to this script will do the job.