Ako vymazat subor rcp?

[Jozef Drahovsky]

Nedari sa mi vymazat subor rcp z primontovaneho nesystemoveho disku

# ls -la
-r-sr-xr-x   1 root  wheel  18584 Jul 19  2010 rcp

# cp rcp aaa <<<<<<<<<<<< spravim kopiu sobru do aaa
# chmod u+s aaa <<<<<<<<<<<< dam rovnake nastavenie

# ls -la
-r-sr-xr-x   1 root  wheel  18584 Jul  4 21:26 aaa
-r-sr-xr-x   1 root  wheel  18584 Jul 19  2010 rcp

# id
uid=0(root) gid=0(wheel) groups=0(wheel),5(operator)

# rm *
override r-sr-xr-x  root/wheel schg for rcp? y
rm: rcp: Operation not permitted

# ls -la
-r-sr-xr-x   1 root  wheel  18584 Jul 19  2010 rcp
#

Viem mi niekto vysvetlit dovod preco subor rcp sa vymazat neda
a subor aaa sa vymazat dal?

Jozef