while (<>) {
    /(\S*)\s+(\S*)/;

    push @a, $1 if length $1;
    push @b, $2 if length $2;
}
[download]

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

Beter as next unless /(\S*)\s+(\S*)/?

Well, I might prefer /(\S*)\s+(\S*)/ or next; on the basis that it's more sequential that way.

-- Randal L. Schwartz, Perl hacker
Be sure to read my standard disclaimer if this is a reply.

The OP was specifically asking about the problem when one of the columns is empty. It seems this solution will just skip any such line, which I don't think was the OP's intention.

Update as jasonk points out, this is rubbish. I'd misread the * as +.

No it won't, it matches 0 or more non-white-spaces, followed by one or more white-spaces, followed by 0 or more non-white-spaces. If the first column is empty, that counts as 0 non-white-spaces and $1 will contain the empty string. If the second column is empty that counts as 0 non-white-spaces and $2 will contain the empty string. The only lines that will get skipped are lines that don't contain at least one white-space character.

Hi Diotalevi,

Unfortunately, this one didn't quite do the trick. It matches the first word of each column on the same line and prints out the first word/unit in each line, like this:

Indice

    1. KETER
                                                4. HESED              
+             131
1.  Quando la luce dell'infinito
2.  Abbiamo diversi e curiosi orologi       23. L'analogia dei contrar
+i            133
                                            24. Sauvez la faible Aisch
+a            136
    2. HOKMAH                               25. Questi misteriosi iniz
+iati         139
                                            26. Tutte le tradizioni de
+lla terra    141
3.  In hanc utilitatem clementes angeli
[download]

Output

First column output:

Indice 1. 2. 3.

Second column output:

1. 4. Quando Abbiamo 24. 2. 26. In
[download]

The output reminds me of one of William Burroughs' ideas. Really cool, actually, but not what I had in mind. Obviously better than I could come up with, though. Plus you didn't have the input file to test it. And of course, the big AND... you came up with your code in about five minutes, well 16 minutes, but you were answering other questions, too.

--
Allolex

Oh... yeah, that data is completely different than I expected. Ah well. That unpack solution someone else posted was nice for fixed length fields.