Rich Kulawiec writes:
> 1. It's a protocol that allows interactive login sessions.
>
> 2. It's a client application that lets you use the protocol to converse
> with a machine running the server on the other end. (In the 'nix world,
> that's "telnetd", short for "telnet daemon".)
>
> It's one of the oldest pieces of 'net technology, though offhand I
> seem to recall that FTP predates it.
Actually, I believe telnet is older. Go pick up "Where Wizards
Stay Up Late." Good read, about the *really* early days of the
Internet (*). Basically they built these hardware boxes - IMPs they
were called - to move packets around. Then they said "Okay, now what
can I use this for?" and the first thing that came to mind was to use
it to, effectively, use another computer as if you were sitting at the
console.
Of course, they didn't think that was very sexy and they went
looking for other things to do with this new technology. I find it
kind of amusing that the currently sexiest technology on the 'net, the
web, is analogous to a telnet session between a browser and server.
(* Now, if I could just find a book that adequately covers the next
ten or fifteen years of the Internet's development...)
Rich's post in answer to "what's a shell" is accurate, but to
simplify a bit:
As Rich said, the heart of the Unix system is called the Kernel -
that's the program that runs when you turn the machine on. It knows
how to work with the hardware and fundamentally how to run programs.
When you log into a Unix box, what you're doing is asking it to
run a program to accept commands from you. That program is called a
shell. The shell runs and keeps running until you log out. It takes
each line you enter and looks at it to figure out if it's a command
built into the shell program, or if it's the name of another, separate
program (**). It carries out the command or runs the other program
and then comes back to you for the next command. It keeps doing this
until you ask it to log you out, whereupon it turns itself off.
The shell stays between you and the Kernel, hence it's sort of
like the shell around a popcorn kernel. That's probably where the
name came from.
(** This approach is, as Rich and I think somebody else noted, part of
the strength of the UNIX design. Although a small subset of
commands are built into each shell, most of the Unix commands
are separate programs. This modularity makes the Unix system
very efficient and very easy to build even more sophisticated
stuff with).
I know you've never used a telnet command and shell access, and a
few other folks have said the same thing. Personally, I can't imagine
using a Unix system without shell access. Some things, command-line
interfaces are best for. Other things (like desktop publishing,
drawing, surfing), point'n click.
Side note: The first shell was called the Bourne Shell, otherwise
known as "sh" (the command used to run it). My favorite shell is
"bash", for "Bourne Again SHell". :-)
Steven J. Owens
[EMAIL PROTECTED]
____________________________________________________________________
--------------------------------------------------------------------
Join The Web Consultants Association : Register on our web site Now
Web Consultants Web Site : http://just4u.com/webconsultants
If you lose the instructions All subscription/unsubscribing can be done
directly from our website for all our lists.
---------------------------------------------------------------------
