TTY, Console or Shell? What's the difference?

[GreyGeek]

http://linux-news.org/index.php/2011...and-a-console/

In Lunix terminology, the short answer is that:
* terminal = tty = text input/output environment
* console = physical terminal
* shell = command line interpreter

For those not as old as I am, "tty" is an abbreviation for "Teletypewriter". If you saw any movies in the 50's and 60's that featured "electronic brains", that cumbersome, waist high, noisy machine with a keyboard in front and paper spewing out the back side which contained printed text output from the "brain"... that is a TTY. Over the years they morphed into a variety of devices, with a display terminal finally replacing the printing on paper.

[Telengard]

Re: TTY, Console or Shell? What's the difference?

Teletypes are a bit before my time. By the time I was aware of computers CRTs were already in common use.

Think of a teletype as a keyboard duck taped to an old fashioned line printer. The two together form a primitive sort of dumb terminal with barely enough electronic intelligence to collect keystrokes and print output on paper. This dumb terminal would be connected to a separate CPU usually in another room, via a slow serial connection.

The expense of shared CPU time combined with the extreme slowness of dumb terminals are the reasons why Unix evolved as it did. Ever wonder why the command to delete files is rm instead of remove, for example? Or why most Unix commands remain silent unless some kind of error occurred? It's because fewer character transactions means less CPU time consumed over a painfully slow serial connection.

[Detonate]

Re: TTY, Console or Shell? What's the difference?

Before the internet, in the military we used TTY as our main way of distant communications. Most official communications that could not wait for snail mail were sent this way. We called them twixes. The output from the printer was in all caps. In later days, I remember having to set your communications program to emulate a specific TTY keyboard to work.