edit:add-var clean-known-hosts~ {|@argv|
  use re
  use str
  use framagit.org/benjamin.vaudour/elv-lib/mods/common
  use framagit.org/benjamin.vaudour/elv-lib/mods/ip
  use framagit.org/benjamin.vaudour/elv-lib/mods/list

  var hosts = [&]
  var ips   = [&]
  var ids   = [&]
  var file  = $E:HOME/.ssh/known_hosts

  fn readfile {
    cat $file | each {|l|
      if (not (str:has-prefix $l '#')) {
        put $l
      }
    } | re:awk {|_ host @rest|
      var id    = (str:join ' ' $rest)
      var ihosts = []
      str:split ',' $host | each {|h|
        set @ihosts = $@ihosts $h
        if (ip:is-ip $h) {
          if (not (has-key $ips $h)) {
            set ips[$h] = [ $id ]
          } else {
            set ips[$h] = [ (all $ips[$h]) $id ]
          }
        } else {
          if (not (has-key $hosts $h)) {
            set hosts[$h] = [ $id ]
          } else {
            set hosts[$h] = [ (all $hosts[$h]) $id ]
          }
        }
      }
    }
  }

  fn searchips {|id|
    if (has-key $ids $id) {
      each {|h|
        if (ip:is-ip $h) {
          put $h
        }
      } $ids[$id]
    }
  }

  fn hashost {|id|
    if (has-key $ids $id) {
      list:contains {|h| not (ip:is-ip $h) } $ids[$id]
    } else {
      put $false
    }
  }

  fn formatlines {
    keys $hosts | order | each {|h|
      order $hosts[$h] | each {|id|
        var hid = (str:join ',' [ $h (searchips $id) ])
        put $hid $id | str:join ' '
      }
    }
    keys $ips | list:sort $ip:comp~ | each {|ip|
      order $ips[$ip] | each {|id|
        if (not (hashost $id)) {
          put $ip $id | str:join ' '
        }
      }
    }
  }

  readfile
  var @lines = (formatlines)
  echo (str:join "\n" $lines) > $file
}