@array = <FILE>;

##</code><code>##

while(<FILE>) {
    push(@array, $_);
}

##</code><code>##

open (DF, "test.txt") || die "Can't read 'test.txt': $!\n"

##</code><code>##

use strict;
use warnings;

##</code><code>##

perl -MO=Deparse -e 'open (DF, "test.txt") || die "Cant read test.txt\n";'

##</code><code>##

die "Can't read test.txt\n" unless open DF, 'test.txt';