my $os = $^O;
my $text_os = $c->createText($x0+570,$y0+10,-text=>"ОС: $os", -font=>'bar_rus', -fill=>'#afb3b0',-anchor=>'s',-tags => ['os']);
eval {
    if ($os =~ /Win/ig){
        use Win32::SerialPort; #we're on Windows
    } else {
        use Device::SerialPort; #we're on Linux
    }
}

##</code><code>##

[pasha@pelikan tk]$ perl dial.pl
Can't locate Win32/SerialPort.pm in @INC (@INC contains: /usr/local/lib/perl5 /usr/local/share/perl5 /usr/lib/perl5 /usr/share/perl5 /usr/lib/perl5 /usr/share/perl5 /usr/local/lib/perl5/site_perl/5.10.0/i386-linux-thread-multi /usr/local/lib/perl5/site_perl/5.10.0/i386-linux-thread-multi /usr/local/lib/perl5/site_perl/5.10.0 /usr/lib/perl5/vendor_perl/5.10.0/i386-linux-thread-multi /usr/lib/perl5/vendor_perl /usr/lib/perl5/site_perl .) at dial.pl line 33.
BEGIN failed--compilation aborted at dial.pl line 33.