Merits and demerits of sandals

One of the great benefits of wearing sandals over shoes is the sheer speed with which they can be put on. No fumbling around for clean pairs of socks; no unlacing; no retying. Ideal. Or they would be but for two minor snags: on at least one day last week, I noticed that my toes had gone blue from the cold; and I've realised that, by wearing sandals, I've taken yet another step along the path of turning into my pater — next thing I know, I'll be turning up to work in a shirt with a huge hole in the elbow and food stains down the front...

Problems with wtmp and Super-UX

Everytime we fiddle with Super-UX, we end up breaking wtmp in some way or other. The problem at its simplest boils down to the following:

1. During shutdown, a record is written to wtmp on the partition /var/sx/adm indicating that the run level has changed to 6 — reboot level.
2. During the first part of the book, the system mounts /, /usr and /var. It does not mount /var/sx/adm.
3. The boot scripts write a record to wtmp, this time on the /var partition, indicating that the system is in multiuser mode.
4. The /var/sx/adm partition, along with its wtmp claiming that the system is at about to reboot, is mounted on top of the wtmp with the multiuser record.
5. The rest of the boot scripts check the run level, decide that the system is about to shutdown, and crap out.

There are a couple of ways to work around the problem. The simplest way is not to use a separate partition for /var/sx/adm.

The second way is silvershooter's R12.2 special: delete symbolic links from /etc/wtmp to /var/sx/adm/wtmp, move the real file to /etc and create some symbolic links from the adm directory (both on /var and /var/sx/adm) pointing to the real version in /etc.

The third method involves adding an entry to the undocumented, but nonetheless extremely potent, /etc/checkfile. This lists any additional file systems that need to be mounted along with / etc as early as possible in the boot sequence. If /var/sx/adm is listed here, it gets mounted before the boot scripts attempt to write out the run level records, which ensures that wtmp correctly describes the current run level of the system.

As I said, we seem to get caught by this every time we attempt to upgrade. How do I know this? Well, last time we upgraded — October 2005, for the curious — I added checkfile to our set of local mods. Somewhat embarrassingly, I then failed to add it to the configuration files, so it wasn't actually copied out with the rest of our localisations. Oops.

Wandering through Princesshay

Strolled home via the new Princesshay development this afternoon. There were all sorts of events, including a guy playing the uke and singing George Formby songs, a couple of transvestite Japanese geishas on tall stilts, people dishing out free bags etc, to celebrate the opening of the main mall. The place was pretty thranged — despite the ukulele playing — packed full of neophiles and gawkers, despite the fact that many of the of the stores, including Apple's, have yet to open.