Update: I just re-read the OP and realised that you'd asked for a regex solution. In which case you could replace the split line below with:

my ($a, $b, $c) = $temp =~ m/(\w+)\n/g;
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(The same comment still applies re assigning to a list).

This is pretty trivial, just split on \n. eg:

#!/usr/bin/perl -w
use strict;

my $temp = "DATA\nFile\nHello\n";

my ($a, $b, $c) = split(/\n/, $temp);

print "$a:$b:$c\n";
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Although, if you have an unknown number of "lines", then you are probably better off spliting them into a list, like so:

my @list = split(/\n/, $temp);
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Cheers,
Darren :)