Here's another approach. This needs Perl version 5.10+ for  \K (if you have < 5.10, let me know; I can supply adjusted code). 

c:\@Work\Perl>perl -wMstrict -le
"use 5.010;
 ;;
 my $s = qq{xxx \@B grab \n this \@E yy zzzz \@B and \n this \n too \@
+E qq};
 print qq{[[$s]]};
 ;;
 my $start = qr{ \@B }xms;
 my $stop  = qr{ \@E }xms;
 ;;
 my $replace = [ 'ZOT', 'ZONK' ];
 ;;
 my $i = 0;
 $s =~ s{ $start \K .*? (?= $stop) }
        { $replace->[ $i++ % @$replace ] }xmsg;
 print qq{<<$s>>};
"
[[xxx @B grab
 this @E yy zzzz @B and
 this
 too @E qq]]
<<xxx @B ZOT @E yy zzzz @B ZONK @E qq>>

[download]

Pay particular attention to Loops's and Corion's remarks here and here about what should happen when the  $replace array is exhausted (I just wrap around and start re-using replacement strings), and also here about using a real templating engine rather than trying to roll your own.

Update: Removed a needless capture group:  .*? vice  (.*?)

In reply to Re: need a regular exdpression in perl by AnomalousMonk
in thread need a regular exdpression in perl by praveenchappa

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