Eskil

                    if {![string equal -nocase $f1 $f2]} {
                        set eq 0
                    }
                } else {
                    if {![string equal $f1 $f2]} {
                        set eq 0
                    }
                }
                # It has been observered that sometimes channels fail to
                # signal eof. Maybe when they come from a pipe?
                # Protect by noticing empty strings.
                if {[string equal $f1 ""] || [string equal $f2 ""]} {
                    break
                }
            }
            if {$eq == 2 && (![eof $ch1] || ![eof $ch2])} {
                set eq 0
            }
            # Errors during close are not interesting
            catch {close $ch1}