Adding the output of tailf -f filename to Tk widget (scrolled)

sashac88 has asked for the wisdom of the Perl Monks concerning the following question:

Hello great monsk!
I asked this question already and received a pretty cool
example from <zentara>. Below it is:

#!/usr/bin/perl
use strict;
use Tk;
use IO::Handle;

my $H=IO::Handle->new;
open($H,"tail -f -n 50 z.txt |") or die $!;

my $main = MainWindow->new;
my $t=$main->Text(-wrap=>'none')->pack(-expand=>1);
$main->fileevent(\*$H,'readable',[\&fill,$t]);

MainLoop;

sub fill {
  my ($w)=@_;
  my $text;
my $text =<$H>;
$w->insert('end',$text);
$w->yview('end');
}
[download]

This works great. The only problem is that when I close the
widget, the prompt isn't returned. Does anyone know
how to overcome this?
Thanks a lot in advance!

Comment on Adding the output of tailf -f filename to Tk widget (scrolled) Download Code

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Re: Adding the output of tailf -f filename to Tk widget (scrolled) by kyle (Abbot) on Feb 26, 2007 at 19:04 UTC
When Perl goes to close the `$H` handle, it will wait for the running command to finish. Because '`tail -f`' never ends, it waits forever. I'd suggest using File::Tail here, but you could also kill the tail yourself. The call to open will return a PID that you can kill when `MainLoop` is finished. `my $tail_pid = open($H,"tail -f -n 50 z.txt \|") or die $!; # etc. MainLoop; kill 9, $tail_pid;` [download]	[reply] [d/l] [select]

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Re: Adding the output of tailf -f filename to Tk widget (scrolled)
by kyle (Abbot) on Feb 26, 2007 at 19:04 UTC

When Perl goes to close the $H handle, it will wait for the running command to finish. Because 'tail -f' never ends, it waits forever. I'd suggest using File::Tail here, but you could also kill the tail yourself. The call to open will return a PID that you can kill when MainLoop is finished.

my $tail_pid = open($H,"tail -f -n 50 z.txt |") or die $!;

# etc.

MainLoop;
kill 9, $tail_pid;
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