use strict;
use warnings;

my $a = ']a\[';
my $b = ']b\[';

#open(HANDLE, "$dataFile") or die "Error: Unable to open data file";

while (my $line = <DATA>) {#(<HANDLE>) {
    chomp $line;
    if ($line =~ /$a/ )  {
        my @fields = split /\].*?\[/, $line;
        print ((join "]a[", @fields). "\n");
    }
    elsif ($line =~ /$b/) {
        my @fields = split /\].*?\[/, $line;
        print ((join "]b[", @fields). "\n");
    }
}
#close HANDLE;