Convert Word doc or docx files into text files?

Note that an excellent source of information for Microsoft Office applications is the Object Browser. You can access it via Tools → Macro → Visual Basic Editor. Once you are in the editor, hit F2 to browse the interfaces, methods, and properties provided by Microsoft Office applications.

Here is an example using Win32::OLE:

#!/usr/bin/perl

use strict;
use warnings;

use File::Spec::Functions qw( catfile );

use Win32::OLE;
use Win32::OLE::Const 'Microsoft Word';
$Win32::OLE::Warn = 3;

my $word = get_word();
$word->{Visible} = 0;

my $doc = $word->{Documents}->Open(catfile $ENV{TEMP}, 'test.docx');

$doc->SaveAs(
    catfile($ENV{TEMP}, 'test.txt'),
    wdFormatTextLineBreaks
);

$doc->Close(0);

sub get_word {
    my $word;
    eval {
        $word = Win32::OLE->GetActiveObject('Word.Application');
    };

    die "$@\n" if $@;

    unless(defined $word) {
        $word = Win32::OLE->new('Word.Application', sub { $_[0]->Quit })
            or die "Oops, cannot start Word: ",
                   Win32::OLE->LastError, "\n";
    }
    return $word;
}
__END__