On 21 Aug 1998, Georges Heinesch wrote:

: Saying 'su - user' is does the same as 'su -l user'. For some reason,
: the 'l' is not necessary. However su(1) doesn't reveal anything about
: this behaviour. Why is this?

"su - user" is a historic usage that is kept for compatibility.  There's
many things like that in various commands, but they aren't documented just
because of how old they are.  :>

-- 
-- Todd Vierling (Personal tv@pobox.com; Bus. todd_vierling@xn.xerox.com)