#! perl
use strict;
use warnings;

while (<DATA>)
{
    / \[ ([^]]+) \] .* \[ ([^]]+) \] .* \[ [^]]+ \] \s+ (.*) /x or next;

    my ($part1, $part2, $part3) = ($1, $2, $3);

    print "1: |$part1| 2: |$part2| 3: |$part3|\n";
}

__DATA__
[part1-dateA] info - [..part2..] [..part3..] part4

[part1-dateB] log - [..part2..] [..part3..] part4

##</code><code>##

22:04 >perl 972_SoPW.pl
1: |part1-dateA| 2: |..part2..| 3: |part4|
1: |part1-dateB| 2: |..part2..| 3: |part4|

22:04 >