ed

The original Unix text editor. See also: awk, sed. More information: https://www.gnu.org/software/ed/manual/ed_manual.html.

• Start an interactive editor session with an empty document:
  ed
• Start an interactive editor session with an empty document and a specific [p]rompt:
  ed -p '> '
• Start an interactive editor session with an empty document and without diagnostics, byte counts and '!' prompt:
  ed -s
• Edit a specific file (this shows the byte count of the loaded file):
  ed {{path/to/file}}
• Replace a string with a specific replacement for all lines:
  ,s/{{regular_expression}}/{{replacement}}/g