yes, its correct. just one correction in the desired output which you have posted in row 2

col1:line1|col2:line1|col3:line1|col4:line1|col5:line1|col6:line1
->col1:line2|          |          |          |col5:line2|col6:line2
          |          |          |          |          |col6:line3
          |          |          |          |          |col6:line4
[download]

This piece of code does what you need except that the field width is fixed.

use warnings;
use strict;

my @row = (
'col1:line1
col1:line2',

'col2:line1',

'col3:line1',

'col4:line1',

'col5:line1
col5:line2',

'col6:line1
col6:line2
col6:line3
col6:line4'
);

format STDOUT =
^>>>>>>>>|^>>>>>>>>|^>>>>>>>>|^>>>>>>>>|^>>>>>>>>|^>>>>>>>>|~~
@row
.

write;
[download]

However using variable field width gives "Out of memory", I do not know why.

format STDOUT =
^*|^*|^*|^*|^*|^*|~~
@row
.
[download]

I need to use variable field width and I know that using variable field ^* alongwith ~~ gives Out of Memory, that's why I'm here to seek solution. Isn't there other logic other than the perlform that can be implemented ?

Hi, I managed to do the get the desired result by below code :

my @row = ('col1 : line1
col1 : line2',
'col2 : line1',
'col3 : line1',
'col4 : line1',
'col5:line1
col5:line2',
'coll6 : line1
coll6 : line2
coll6 : line3
coll6 : line4'
);

while ( join('',@row) ) {
        for(my $i=0;$i<=$#row;$i++) {
                my @a = split (/\n/,$row[$i]);
                my $s = shift(@a);
                print  ($s? $s . '|' : '|');
                $row[$i] = join("\n",@a);
        }
        print "\n";
}
[download]

it gives desired output as :

col1 : line1|col2 : line1|col3 : line1|col4 : line1|col5:line1|coll6 :
+ line1|
col1 : line2||||col5:line2|coll6 : line2|
|||||coll6 : line3|
|||||coll6 : line4|
[download]

but condition in while loop looks kinda ugly, can be below code be further reduced ?