yes, I tried it this way:

#! /usr/bin/perl

use strict;
use warnings;
use IO::File;


my @fh;
my @file_names = ("output1.txt", "output2.txt", "output3.txt");

while ( <> ){
    for (my $i=0; $i<=$#file_names; $i++){
        $fh[$i]= IO::File->new( ">$file_names[$i]" ) || die "Cannot op
+en $file_names[$i]: $!.\n";
        print {$fh[$i]} "$_";
    }
}
print "done.\n";
[download]

this script produces three output files, each contains the input filename that the user writes into the command line. Do I have to somehow open the input files in the script?

Do I have to somehow open the input files in the script?

Yes.

open my $input_file, '<', $input_filename or die "Cannot open input fi
+le $input_filename:  $!.\n";
while (my $input_line = <$input_file>) {
    chomp $input_line;
    print "[$input_line]\n";
}
close $input_file;
[download]

the input file should come from the command line. i don't want to determine the file within the script. Doesn't <> within the while loop open the files the users enters in the command line? If not, how can i implement the open command in my script?