my @lines = split /\n/, <<EOD;
D1001     SNAM1        1     101      XYZ1234      21.11
D1001     SNAM1        1     102      XYZ2234      22.12
D1002     SNAM2        1     201      PQR2234      12.12
D1002     SNAM2        2     202      PQR2234      32.12
D1002     SNAM2        3     203      PQR2234      52.12
D1002     SNAM2        4     204      PQR2234      37.12
D1001     SNAM1        2     103      XYZ1234      22.12
D1003     SNAM3        1     301      ABC1234      22.12
D1002     SNAM2        5     205      PQR2234      37.12
D1001     SNAM1        4     104      XYZ1234      22.12
EOD

@lines = map { $_->[0] }                      # extract lines back out
         sort {                               # sort on split columns
               $a->[1][0] cmp $b->[1][0]      #  index 0 is 'col1'
            || $a->[1][1] cmp $b->[1][1]      #  col2
            || $a->[1][4] cmp $b->[1][4]      #  col5
         }
         map { [ $_ => [ split /\s+/, $_ ] ] } # [ 'line1' => ['col1',...] ]
         @lines;

print "$_\n" foreach @lines;