# On the commandline
 perl -0wne'print "$_\n" for /img\s+src="([^"]+)"/igsm'  filename

##</code><code>##

# Since HTML tags can be split into multiple lines, you need all the
# content as one string
open Fh, "<", "filename" or die "filename: $!\n";
my $file = do { local $/; <Fh> };
close Fh;

for ($file =~ /img\s+src="([^"]+)"/igsm){
    print "$_\n";
}