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From: patkar@amide.ecn.purdue.edu (The Silent Dodo)
Newsgroups: comp.editors
Subject: A vi question
Keywords: substitute, vi
Message-ID: <1990Aug12.194738.7902@ecn.purdue.edu>
Date: 12 Aug 90 19:47:38 GMT
Sender: news@ecn.purdue.edu (USENET news)
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Organization: Purdue University Engineering Computer Network
Lines: 22

I need to do the following in vi.

I have a file containing multiple occurances of a single letter.
A sample line is 

ccccoooossss

I need to replace all quadruple occurance by a single letter.
Thus the above line should become

cos

I tried something like

:1,$s/\(a-zA-Z)\)\1\1\1/\1/g

Vi does not allow \1 in the pattern to be searched.
Any pointers will be appreciated. 


 -- Anant
 (patkar@cn.ecn.purdue.edu)