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

Using constantly changing varibles in perl. I have a file that uses tail to count every new line per second in a file. i am trying to change it so the varible $line_ps will not make a newline when printing. right now what im doing is: 
system 'clear';
print "Lines P/s: $line_ps";
print "Average Lp/s: $average";
print "Total lines: $t-lines";

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Im trying to make it so i do not need to clear it anymore. Where i can just have that variable printed change every time the variable changes.

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Re: Printing changing variable in perl
by toolic (Bishop) on Feb 26, 2014 at 17:20 UTC
    You can use \r to back up and print over a line: 
    use warnings;
use strict;

$|++;
for (1 .. 3) {
    print "\r$_";
    sleep 2;
}
print "\n";

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      never, never, never suspected the existence of this! thanks Toolic
      For posterity, as pointed by ambrus you can find this in docs but i never understood what also wiki says: A carriage return, .. is .. a mechanism used to reset a device's position to the beginning of a line of text.

      L*
      There are no rules, there are no thumbs..
      Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.
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Re: Printing changing variable in perl
by hippo (Archbishop) on Feb 26, 2014 at 17:42 UTC

    I suspect you might benefit from one of the many Curses modules on CPAN.

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