#!/usr/bin/env perl 
use strict;
use warnings;

if (scalar @ARGV) {
        print "Processing CLI args: @ARGV ...\n";
} else {
        print "Reading from STDIN\n";
        while (<>) {
                chomp;
                print "Got $_\n";
        }
}
[download]

You may also be interested in the -t file test (on line 23):

    -t  Filehandle is opened to a tty.
[download]

For example:

#!/usr/bin/perl

use strict;
use warnings;
use feature qw( say );
use File::Basename;

my $iam = basename($0);

if (-t *STDIN) {
    my $nargs = @ARGV;
    say "Script '$iam' called from a terminal with $nargs arg(s):";
    for (my $idx = 0; $idx < $nargs; $idx++) {
        printf "  %2d.  %s\n", $idx+1, $ARGV[$idx];
    }
} else {
    say "Script '$iam' is receiving input from a pipe";
}
[download]

Script 'script' called from a terminal with 3 arg(s):
   1.  arg1
   2.  arg2
   3.  arg3
[download]

Script 'script' is receiving input from a pipe
[download]

    while (<STDIN>) {
        say "Got input:  $_";
    }
[download]

Hello burszuras,

Welcome to the Monastery. Can you provide us a bit more information? What do you mean is not so clear what you want. What you have tried and you want to update/modify?

I found a similar question Command lines Args and STDIN, but most likely is not what you are looking.

Looking forward to your update, BR