If you want to dump all output to the text object, try the backticks command:

my $out = `command`;
$text->insert('end', $out);
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If you want to process things line by line, try opening a pipe:

open OUT "command |"
   or die "Could not open command: $!\n";
while (my $line = <OUT>) {
   # process $line ...
   $text->insert('end', $line);
}
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