specifically for such a simple application. There was simply no justification for
designing yet another language.
I had been thinking about writing an Expect-like program after helping Scott Paisley
write a program to automate the initial login and command in a telnet session. The
program understood only a few simple commands. For instance, find waited for a
single fixed string to arrive. Every session ended in a permanent sort of interact with
a single telnet process. There were no variables and no flow control commands such as
if. And the program used pipes instead of ptys. The program solved our immediate
problem, but it had a lot of special-case coding and I thought it could be generalized.
This was in 1987.
For a long time I considered borrowing a shell, integrating the Expect primitives into it,
and then re-releasing it. However, shells are not intended to be used this way and I did
not have any interest in maintaining a shell once I had stuck my hands in it. At that
time, shells were renowned for being messy beasts. For example, the C shell was well
known for not having consistent and robust parsing. And the Bourne shell had
stimulated the Obfuscated C Code Contest—a contest that actually celebrates and revels
in torturous code. I wanted something else.
I was fortunate to be able to attend the 1990 Winter USENIX Conference in
Washington DC (January 22-26). I had been thinking about writing something like
Expect for several years, and I decided to go there and ask some wizards about what
they did for portable language facilities. To my delight, there was a talk at the
conference addressing that very topic.
John Ousterhout, a professor at the University of California at Berkeley, had designed a
language for embedding into applications—my very need! By the middle of the talk, I
knew I wanted to try using it. At the end of talk, when he said it was freely available, I
swooned.
Four days later, I had a copy of Tcl. I couldn't believe it. It was not only everything John
had promised, it was also easy to use and well documented. By February 7 (eight days
after first downloading Tcl), I had a working, albeit primitive, Expect. It had the core of
what Expect has today: send, expect, spawn, interact, plus a logging function. At
that time, the compiled Tcl code was about 48K, while Expect added on another 12K.
The idea of a control language being larger than the application seemed peculiar, but it
worked too well to go back to the old ways of designing ad hoc interfaces.
Even with minimal functionality, it clearly suggested some interesting uses and I
thought that it might be nice to inform others. I had a USENIX Call-For-Papers hanging
next to my workstation. It said:
"The final deadline for receipt of submissions is February 7, 1990. Abstracts received
after this deadline will not be considered."
It was February 8, one day after the deadline. I sat down, banged out the requested
extended abstract, and sent it in on the 9th.
[ ]
It was accepted with top marks by all the
referees and appeared at the very next conference. No person was more astonished by
this rapid publication describing a Tcl-based application than John. (John published
