proc input {message varname {default {}}} {
  upvar $varname input
  set input {}
  puts $message
  while {$input == {}} {
    puts -nonewline "% "
    flush stdout
    gets stdin input
    if {$input == {}} {set input $default}
  }
  puts ""
}

proc inopt {message varname} {
  upvar $varname input
  set input {}
  puts $message
  puts -nonewline "% "
  flush stdout
  gets stdin input
  puts ""
}

proc paswd {message varname} {
  upvar $varname input
  set input {}
  puts $message
  exec stty -echo
  while {$input == {}} {
    puts -nonewline "% "
    flush stdout
    gets stdin input
  }
  exec stty echo
  puts "\n"
}