Editing TECO (text editor) (section)

==As a programming language==
The obscurity of the TECO programming language is described in the following quote from "[[Real Programmers Don't Use Pascal]]", a letter from Ed Post to Datamation, July 1983:

{{quote|It has been observed that a TECO command sequence more closely resembles transmission line noise than readable text. One of the more entertaining games to play with TECO is to type your name in as a command line and try to guess what it does. Just about any possible typing error while talking with TECO will probably destroy your program, or even worse - introduce subtle and mysterious bugs in a once working subroutine.<ref>
{{cite journal
 |last=Post |first=Ed
 |date=July 1983
 |title=Real Programmers Don't Use PASCAL
 |url=http://www.pbm.com/~lindahl/real.programmers.html
 |journal=[[Datamation]]
 |volume=29 |issue=7 |pages=263–265
}}</ref>}}

According to Craig Finseth, author of ''The Craft of Text Editing'',<ref>
{{cite book
 |last=Finseth |first=Craig A.
 |year=2006
 |title=The Craft of Text Editing
 |publisher=[[Lulu.com]]
 |url=http://www.finseth.com/craft
 |isbn=978-1-4116-8297-9
}}</ref> TECO has been described as a "write-only" language, implying that once a program is written in TECO, it is extremely difficult to comprehend what it did without appropriate documentation.

Despite its syntax, the TECO command language was tremendously powerful, and clones are still available for [[MS-DOS]] and for [[Unix]].

TECO commands are characters (including control-characters), and the prompt is a single asterisk:
 *

The escape key displays as a dollar sign, pressed once it delineates the end of a command requiring an argument and pressed twice initiates the execution of the entered commands:
 *$$