-# determine input data source
-my $input;
-if (@ARGV) {
- # manual contents specified (either piped or filename(s) given)
- $input = \*ARGV;
-}
-else {
- # automatic download from official website
- require LWP::Simple;
- my $contents = LWP::Simple::get('http://www.ietf.org/rfc/rfc1345.txt')
- or die "Couldn't download RFC-1345 from ietf.org";
- open $input, '<', \$contents; # emulate file handle
-}
+# expect input data source at command line
+@ARGV or die "Specify input source file or - for STDIN\n";