bowei_99 has asked for the wisdom of the Perl Monks concerning the following question:

How can I dynamically update a value on STDOUT? I have a value that uses File::Tail to parse a log and return a valu each time, which is working. The idea is that it gives the user a realtime summary status of the application. However, when displaying the results, I don't really need to show a history of values, only the current value on STDOUT. In other words, instead of printing out the following as a string:

1 3 10 20

it should print 1, then replace that with a 3, then replace that with a 10, then with 20, as it parses the file and determines the value.

I had thought that using 

use IO::Handle;

*STDOUT->autoflush();

[download]
would work, but it seems to be for something else. What is the suggested way of doing this?

-- Burvil

Replies are listed 'Best First'.
Re: How to dynamically update value in STDOUT?
by Sidhekin (Priest) on Nov 05, 2007 at 01:44 UTC

    I think you are looking for a carriage return (without line feed): 

    sub do_stuff {
  sleep 2; # for the sake of the example ..
}

$|=1; # turn off buffering, or you may never see what you write ...

my @v = (1, 3, 10, 20);
while (@v) {
  printf "\r%2d", shift @v;
  do_stuff();
}

    [download]

    print "Just another Perl ${\(trickster and hacker)},"
    The Sidhekin proves Sidhe did it!

[reply]
[d/l]
[select]
      Thanks. Yes, that was it. I had tried your suggestion earlier, but forgot the '\r'. It's working now.

      -- Burvil

[reply]

Back to Seekers of Perl Wisdom