How to clean the Output - perl

Question

I open a file and print some data on the screen , but I want to clean the screen after I output the data , I use clear; in the program but I don't see the effect of clean . It didn't clean .Does there
any command or function can let me do that?
I want to see the contain of a file only , but not to see some of the previous file on the screen ...
Here is my programs
`ls > File_List`;
open List , "<./File_List";
while(eof(List)!=1)
{
$Each = readline(*List);
chomp $Each;
print $Each;
print "\n";
`clear`;
open F , "<./$Each";
while(eof(F)!=1)
{
for($i=0;$i<20;$i++)
{
$L = readline(*F);
print $L;
}
last;
}
close(F);
sleep(3);
$Each = "";
}
close List;
Thanks

Answer 1

Your program uses non-idiomatic Perl. A more natural style would be
#!/usr/bin/env perl
use strict;
use warnings;
no warnings 'exec';
opendir my $dh, "." or die "$0: opendir: $!";
while (defined(my $name = readdir $dh)) {
if (-T $name) {
system("clear") == 0 or warn "$0: clear exited " . ($? >> 8);
print $name, "\n";
system("head", "-20", $name) == 0 or warn "$0: head exited " . ($? >> 8);
sleep 3;
}
}
Instead of writing a list of names to another file, read the names directly with opendir and readdir. The defined check is necessary in case you have a file named 0, which Perl considers to be a false value and would terminate the loop prematurely.
You don’t want to print everything. The directory entry may be a directory or an executable image or a tarball. The -T file test attempts to guess whether the file is a text file.
Invoke the external clear command using Perl’s system.
Finally, use the external head command to print the first 20 lines of each text file.

Answer 2

clear isn't working because the control sequence it outputs to clear the screen is being captured and returned to your program instead of being sent to the display.
Try
print `clear`
or
system('clear')
instead

Answer 3

The solution you provided doesn't work because the clear command is performed in a sub-shell. I suggest the use of a CPAN module (and multi platform supported): Term::Screen::Uni
Example:
use Term::Screen::Uni;
my $screen = Term::Screen::Uni->new;
$screen->clrscr;

Answer 4

Use system(), it works.
system("ls > File_List");
system("clear;");