split(/\|/, ...)

##</code><code>##

my $re = qr/\|/;
split($re, ...)

##</code><code>##

my $re = "\\|";  # \|
split($re, ...)

##</code><code>##

my $str = "|";             # |
my $re = quotemeta($str);  # \|
split($re, ...)

##</code><code>##

my $sep = $arr[2];
split(quotemeta($sep), ...)