use strict;
 
my $arc = 'ARCSERVE.NLM';
my $slurped = do {local $/; <DATA>};

#my ($temp) = $slurped =~ /^($arc.*)\n\n/sm;
my ($temp) = $slurped =~ /($arc.*?\n)\n\n/s;

print $temp;
 
__DATA__
not this one
or this one
asdffARCSERVE.NLM
or even this one
----------------
ARCSERVE.NLM
sign here and here
and here and here

and here


----------------
but not here
blah blah blah
blah blah blah