What Does Line Editor Mean?
A line editor is a basic type of computer-based text editor whereby one line of a file can be edited at a time. Line editors were the precursor to document editing software that is commonly used today. Line editors were used before interactive video graphic screens were commonly available in computers.
Techopedia Explains Line Editor
The editing of a single line at a time was due to the unavailability of graphical interface screens, cursors and memory, hence an average computer operator used a teleprinter, whereby a printer was directly attached to a keyboard and changes could not be made once the text had been typed. Typically the text is not entered into the document until a complete line has been typed. The operator can view the typed form once entered, but cannot go back to a previous line to edit it.
While line editors are no longer widely used, they are still utilized in some applications, such as in shell scripts and MUD systems.