almost.p6

$ perl -E 'open(FH, "| wc"); print(FH "hello world"); close(FH);'
      0       2      11

$ perl6-p -e 'my $fh = "wc".IO.open(:p, :w); $fh.print("hello world"); $fh.close;'
/bin/sh: 1: /home/froggs/dev/rakudo/wc: not found

$ perl6-p -e 'my $fh = "/usr/bin/wc".IO.open(:p, :w); $fh.print("hello world"); $fh.close;'
      0       2      11

$ perl6-m -e 'my $fh = "/usr/bin/wc".IO.open(:p, :w); $fh.print("hello world"); $fh.close;'
Invalid open mode: 104017744
  in method open at src/gen/m-CORE.setting:13177
  in method open at src/gen/m-CORE.setting:13167
  in block  at -e:1

$ perl6-j -e 'my $fh = "/usr/bin/wc".IO.open(:p, :w); $fh.print("hello world"); $fh.close;'
Unhandled file open mode 'wp'
  in method open at gen/jvm/CORE.setting:13179
  in method open at gen/jvm/CORE.setting:13169
  in block  at -e:1