A few questions...

[Darren Pilgrim]

Daniel Molina Wegener wrote:
> Hello,
> 
>    I need information about few things, I hope someone can help
> me and thanks in advance.
> 
> a) Is there any function or variable that tells me which is the
>    root user UID in the system, or root always have 0 and it's
>    an "elegant" option to compare the variables or structure
>    members against zero.

Root is always UID 0.  Checking UID == 0 is the common practice for 
determining if the effective UID has root priveleges.

> b) Can normal users look for system processes or kernel threads?

Yes, depending on the value of the security.bsd.see_other_uids sysctl. 
If security.bsd.see_other_uids=0, non-root users can only see their own 
processes.

> c) Can root look for system processes or kernel threads?

Yes, regardless of the value of security.bsd.see_other_uids.