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From: Jonathan McKeown <jonathan@hst.org.za>
Organization: Health Systems Trust
To: freebsd-questions@freebsd.org
Date: Thu, 26 Apr 2007 12:57:35 +0200
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Subject: Re: [OT] simpliest way to process this data file
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On Thursday 26 April 2007 08:51, Zhang Weiwu wrote:
> On Thu, 2007-04-26 at 11:18 +0800, Zhang Weiwu wrote:
[snip]
> > I have a data file formatted like this each block of data consist of
> > several lines; blocks are separated by empty lines like this
> >
> >         This is a
> >         block
> >         of data
> >         with lines
> >
> >         and another block
> >         of
> >         data
> >
> > The task is to move the last line of each block to the first line of the
> > block. So the processed data look like this:
> >
> >         with lines
> >         This is a
> >         block
> >         of data
> >
> >         data
> >         and other block
> >         of
[snip]
I would use Perl, which can read in a paragraph at a time. Assuming you don't 
mind having multiple blank lines in the input replaced by a single blank 
line, this Perl commandline will do what you want:

perl -l -00 -pe 's/(.*)^(.*)$/$2\n$1/ms' datafile

Read perldoc perlrun for the flags, and perldoc perlre to understand the regex 
(in particular the m and s modifiers).

Jonathan