OT: Calling unix experts, Need "vi" assistance Options

[Rusty]

Sorry for the OT post.

I have a text file that I need to edit.

I need to edit every record on that file (record positions 34-37) to change whatever is in those positions (only) to a four digit number. What is currently in those positions varies dramatically.

My only text editor I have on the system is vi.

Anyone got a command I can use?

thanks,
Lawrence

[bperry]

Man its been a while but I love vi and regular expressions.
We used to have contests like this at work back in the 80's
to see who could do it in the shortest (most obtuse) way.

Its been years since I've done any of this
but you could try something like this from the command line.

:1,$s/^\(..... place 32 dots here\)....\(.*\)/\1####\2/

This should modify the entire file.

There should be EXACTLY as many periods/dots between the
first set of parens as you want to skip over.
Then EXACTLY as many periods/dots between the first
set of parens and second parens as you want to replace.
Replace #### with the new numbers/text you want.
(doesnt have to be the same length as what is being replaced)
This works by matching the begining characters and puting them in a substring
then matching the replacement characters and finally puting the tail
end of the string in another stubstring. Then it puts the first
substring back, then the new text, followed by the second substring.

Hopefully, I remembered correctly and the WEB tools didn't mangle
any of the special characters.


(NOTE: I did download a vi versions for windows and this does work.)
Regular expressions are cool! and very consistent across unix.

For all of you wondering how come I got so deep into such
techno dweeb stuff, its because back in the "old days" when you
were on a 300 baud modem, you wanted as little screen activity
as possible and the ":" commands of vi are exactly the same as
the "ed" commands which is where vi came from.

--- bill