Editing Echo (command) (section)

==History==
<code>echo</code> began within [[Multics]]. After it was programmed in [[C (programming language)|C]] by [[Douglas McIlroy|Doug McIlroy]] as a "finger exercise" and proved to be useful, it became part of [[Version 2 Unix]]. <code>echo -n</code> in [[Version 7 Unix|Version 7]] replaced <code>prompt</code>, (which behaved like <code>echo</code> but without terminating its output with a line delimiter).<ref name="reader" />

On [[PWB/UNIX]] and later [[Unix System III]], <code>echo</code> started expanding [[Escape sequences in C|C escape sequences]] such as <code>\n</code> with the notable difference that octal escape sequences were expressed as <code>\0ooo</code> instead of <code>\ooo</code> in C.<ref name="mascheck-echo" />

[[Research Unix|Eighth Edition Unix]] <code>echo</code> only did the escape expansion when passed a <code>-e</code> option,<ref name="man echo" /> and that behaviour was copied by a few other implementations such as the builtin <code>echo</code> command of [[Bash (Unix shell)|Bash]] or [[zsh]] and GNU <code>echo</code>.

On [[MS-DOS]], the command is available in versions 2 and later.<ref name="RUNNINGMSDOS" />