Switches for grep

[fergus]

Although a year old Knoppix 5.1.1 seems to have everything one could need and in a recent version. However, although "man grep" suggests that the switch -P is available, it isn't. Nor is the longhand equivalent --perl-regexp and nor is the tweaked executable pcregrep (Perl Compatible Regular Expressions grep).
I really want to be able to use a command like
grep -Pl "\x00" {filelist}
Any ideas how to use the Knoppix-supplied version of grep that will achieve this?
Thank you.
Fergus