Another dumb question...

[murphy pope <pope_murphy hotmail com>]

Everything that I've read says that the 'su' command will change my Linux user ID but not my identity.  Here's what I see:

# id -Z
root:staff_r:staff_t
# su fred
Your default context is fred:sysadm_r:sysadm_t.

Do you want to choose a different one? [n]n
$ id -Z
fred:sysadm_r:sysadm_t

My identity changed from 'root' to 'fred'.  Bug?  That seems a pretty fundamental flaw considering that every document that I've read uses 'su' to explain the difference between a user ID and an identity.

By the way, I see the same result whether I use 'su' or 'su -'.  I see the same result (a change in identity) whether I su from root to fred or from fred to root.

So which one is right?  The documentation or the code? 

    -- Murphy