Re: ! in PS1 in posix mode

[Bob Proulx]

Linda Walsh wrote:
> Haven't used ksh for some time....I thought the '!' stuff came
> from csh?  It seemed so pointless, since having to look up
> things by command number I thought, was way too much work... searching
> via a string in the line seemed so much faster...

You are not thinking about the environment in which csh was designed.
If you were not working on a CRT but were on a paper terminal then it
wasn't possible to implement a C-r reverse-search through the command
history and WYSIWYG editor.  That is why we have 'ed' and 'ex'
although at the time I used 'qed'.

During that era CRTs were new fangled things.  At the time csh was
popular most of us used paper terminals!  I missed the teletypes by a
few years but my introduction to computing at university was on
printing paper terminals.  Students were only allowed on the low end
paper terminals.  The CRTs were reserved for faculty and grad
students.  (Almost all of my CS classes were on paper terminals
dialing a rotary phone with an acoustic coupler at 300 bps to a
Honeywell.  "Brrappph" was the sound the terminal made as it printed
out lines of paper.  It would shake the table as the print head on the
carriage moved back and forth.  Working in the computer lab was very
LOUD back then.  Especially in a room full of other people all working
with the same type of terminals.)

In that environment the !67 type of commands make a lot of sense.  One
always put the command number in the prompt so that it was printed out
with the command.  Once run that number would always be unchanged
forever on the paper and easy to see and know exactly what was going
to happen.  Just look over the printed out history on the paper and
select some program arguments from one command and other arguments
from other commands and stitch them together.  Since they were all in
the growing roll of trash piling up out of the back to the terminal it
was fairly easy to do.  Take a pen and underline the numbers you used
often in that session to make them easier to see.

Bob