when you rlogin and your tty is pts/0 (/dev/pts/0) you might get the following message when trying to execute logname:
logname: could not get login name
It appears that rlogind doesn't update /etc/utmp This of course appears to be intermittent if you have several clients doing rlogins, the first one that uses /dev/pts/0 will have the problem, the other will probably be fine. This is more of a problem if you are using the logname command in something like /etc/profile
Only noticed this on 11.23 (both IA and PA platforms). Both had PHNE_32818 installed. A possible fix is PHNE_33792, but I couldn't test it. A workaround is to use the variable $LOGNAME instead of the command logname.