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From: bill@hao.UUCP
Newsgroups: comp.unix.questions
Subject: The solution to the sed - multiple lines problem
Message-ID: <574@hao.UCAR.EDU>
Date: Wed, 11-Mar-87 19:11:50 EST
Article-I.D.: hao.574
Posted: Wed Mar 11 19:11:50 1987
Date-Received: Fri, 13-Mar-87 01:50:00 EST
Organization: High Altitude Obs./NCAR, Boulder CO
Lines: 33


This is the solution of the "sed - matching multiple lines on input" problem
which I posed a few days ago.  I thought I'd post it to the net to let people
know I've solved it and just how to do it.
Given the following input:

one
two
three

and the following sed editor script:

s/one\ntwo\nthree/one, two, three/g

Why don't it work?  Well here's my hypothesis:
	Sed reads the first line which contains the string "one\n" and 
discards the newline.  So the pattern space looks like "one".  Of course the
pattern "one\ntwo\nthree" won't match that.  So the second line gets read 
and the same thing happens, then the third line and so nothing ever matches.
The solution was to build up the pattern space by using the "hold buffer".
The following sed script does the job:

/one/!b
N
/two/!b
N
/three/!b
s/\n/, /g 

See the sed writeup to understand the commands !, b and N.  Thanks to all who
responded with positive suggestions.

--Bill