With the Oracle client 10.2.0.1.0 installer if you are automating the install with a response file, set UNIX_GROUP_NAME to something like say 'dba', then run the install but you are not in the dba group the install will fail with:

SEVERE:S_OWNER_SYSTEM_EPERM

I found nothing useful via a search for that error so I thought I'd post something. It would seem that you need to set UNIX_GROUP_NAME to a group you are in. Oddly none of the files that are written out end up owned by that group, so it doesn't seem like the installer really needs those privileges.

I'm trying to package the Oracle client for our internal packaging system, I'm not a DBA and wouldn't normally be a member of the dba group.