use warnings;
use strict;

open OUT, '>', 'delme.txt';
print OUT <<TEXT;
1) how can someone know what is the current edited file's name ? question
TEXT
close OUT;

@ARGV = ('delme.txt');
$^I = ".bak";

while (<>) {
    if ($. == 1) {
        print STDOUT "File geing processed is $ARGV\n";
        open OUT, '>', $ARGV or die "Can't open $ARGV: $!";
        print OUT <<"            NEWTEXT";
            2) can someone make modifications on that file, isnt it already opened by the <> diamond operator?
            NEWTEXT
    }
    
    print;
    print STDOUT;
}

close OUT;
print "\n";
open IN, '<', 'delme.txt';
print <IN>;
close IN;

##</code><code>##

File geing processed is delme.txt
1) how can someone know what is the current edited file's name ? question

            2) can someone make modifications on that file, isnt it already opened by the <> diamond operator?