# ed > The original Unix text editor. - Start ed, editing an empty document (which can be saved as a new file in the current directory): `ed` - Start ed, editing an empty document, with `:` as a command prompt indicator: `ed -p :` - Start ed editing an existing file (this shows the byte count of the loaded file): `ed -p : {{path/to/file}}` - Toggle the printing of error explanations. (By default, explanations are not printed and only a `?` appears): `H` - Add text to the current document. Mark completion by entering a period by itself in a new line: `a{{text_to_insert}}.` - Print the entire document (`,` is a shortcut to the range `1,$` which covers the start to the end of the document): `,p` - Write the current document to a new file (the filename can be omitted if `ed` was called with an existing file): `w {{filename.txt}}` - Quit ed: `q`