% perl -MData::Dumper -e 'my $i = ""; my @arr = qw/fe fi fo fum/; my @p = grep { ! /$i/ } @arr; print Dumper(@p);'
 % perl -MData::Dumper -e 'my $i = " "; my @arr = qw/fe fi fo fum/; my @p = grep { ! /$i/ } @arr; print Dumper(@p);'
$VAR1 = 'fe';
$VAR2 = 'fi';
$VAR3 = 'fo';
$VAR4 = 'fum';