define line($file, $line, $ensure = 'present') {
   case $ensure {
      default : { err ( "unknown ensure value ${ensure}" ) }
      present: {
         exec { "/bin/echo '${line}' >> '${file}'":
            unless => "/bin/grep -qFx '${line}' '${file}'"
         }
      }
      absent: {
         exec { "/usr/bin/perl -ni -e 'print unless /^\\Q${line}\\E\$/' '${file}'":
            onlyif => "/bin/grep -qFx '${line}' '${file}'"
         }
      }
   }
}