When outputting HTML, it’s often handy to be able to turn any URL, such as http://www.whatever.com, into a hyperlink, such as http://www.whatever.com.
You can do this with a regular expression in Perl:
open (FILE, "myfile.txt");while () { if (/http:/) { s{(http:[^s]*)} {$1}gs; } print;}
Any string in myfile.txt which contains http: will be turned into a hyperlink.