You probably are looking for a Tk::fileevent example. Here is a basic one. The Tk script should be started with the name of the file to log. In this example I use a file called z.log. Below the main Tk script is a pumper script which will write to z.log every .1 seconds, to take the place of your c script.

Tk::fileevent works like you want, because everytime the file is written to by your c program, the fileevent fires and inserts it into the display. 

#!/usr/bin/perl
# tktail pathname
use warnings;
use strict;
use Tk;

#usage tktail z.log

my $pid = open(H, "tail -f -n 25 $ARGV[0]|") or die ;

my $mw = MainWindow->new;

$mw->fontCreate('big',
   -family=>'courier',
  -weight=>'bold',
  -size=>int(-24*24/14));

my $t = $mw->Text(-width => 80, -height => 25, 
                  -wrap => 'none',
                  -bg => 'lightyellow',
                  -font => 'big')->pack(-expand => 1);

$mw->fileevent('H', 'readable', [\&fill_text_widget, $t]);
$mw->OnDestroy(\&quitCB);
MainLoop;

sub fill_text_widget {
my($widget) = @_;
my $text = <H>;
$widget->insert('end', $text);
$widget->yview('end');
} # end fill_text_widget


sub quitCB {
kill 9,$pid or die $!;
exit;
}

[download]
and the test pumper script 
#!/usr/bin/perl
use warnings;
use strict;

# pumps the file for testing

$| = 1;

open (ZH, "> z.log") or die "$_\n";

# autoflush ZH
my $ofh = select(ZH);
$|   = 1;
select($ofh);

while(1){
 print ZH time."\n";
 print '#'; #action indicator
 select(undef,undef,undef,.1);
}

[download]
I'm not really a human, but I play one on earth. ..... an animated JAPH

In reply to Re: Printing a refreshed file in Perl Tk by zentara
in thread Printing a refreshed file in Perl Tk by kkma

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