Ed is a text editor, and similar to sam -d. Using the % sam -d examples from Sam, it's possible to use % ed. The mentioned examples are from a Drawterm Rio rc prompt.

  % cd samtest
  % cp /lib/ndb/local local-1ed

  % ed local-1ed
  291
  /ip=
  ip=127.0.0.1 sys=localhost dom=localhost
  s/ip=/#ip=
  #ip=127.0.0.1 sys=localhost dom=localhost
  $
  #ip=127.0.0.1 sys=localhost dom=localhost
  a
  ip=YOUR_IP sys=plan9 dom=plan9 dns=205.166.94.20
  .
  w
  341
  q
  %

  % cp /rc/bin/termrc.local termrc.local-1ed
  % ed termrc.local-1ed

  % ed termrc.local-1ed
  424
  $
  cpu=CP
  a
  ip/ipconfig -g 205.166.94.1 ether /net/ether0 YOUR_IP 255.255.255.0
  ndb/cs
  ndb/dns -r
  .
  w
  510
  q
  %

• ctl-h is backspace, kind of; ctl-u erases the current line. As seen, with the VPS Plan 9 console prompt ctl-h backspace, the screen output may not be what one would expect¹.
• To detach the Plan 9 console prompt (%), while retaining the ability to reattach it without rebooting your server, press ctl-] to close the prompt (%). Then, press 'q' to disconnect the VPS Maintenance Shell menu, and ssh connection. You can return again with another ssh to the allocated VPS server, an SDF VPS Maintenance Shell menu review, and a press on the “c” key to connect to the Plan 9 console prompt (%).
• ed and “% sam -d” are available in the Plan 9 Image. They may be used for setting the DNS, or other tasks from the Plan 9 VPS console prompt (%), before Drawterm is accessible. An ed cheat-sheet is available. Additional editors are operational from a Drawterm Rio rc prompt: acme, sam, or % sam -d.

¹ Control keys -- Available at the SDF Boot Camp VPS server console prompt

Editor reference: