#!/usr/bin/perl

use strict;
use warnings;

while (<>) {
    my @ctrl = ( /([[:ctrl:]])/g );
    if ( @ctrl ) {
        my $cstr = join ",", map { sprintf "x%2.2x",ord() } @ctrl;
        s/([[:ctrl:]])/sprintf("||%x2.2x||",$1)/eg;
        printf( "line %d: ctrl-chars %s in <<%s>>\n",
                $., $cstr, $_ );
    }
}

##</code><code>##

script_name  memo.txt > memo.errs