Sorting out what the Single Unix Specification is and covers
I've linked to the Single Unix Specification any number of times, for various versionsof it (when I first linked to it, it was at issue 6, in 2006; it'snow up to a 2018 edition ). But I've neverbeen quite clear what it covered and didn't cover, and how it relatedto POSIX and similar things. After yesterday's entry got me looking at the SuS site again, Idecided to try to sort
A handy diff argument handling feature that's actually very old
Some time ago I stumbled over a useful feature in the diff on ourLinux machines (ie, GNU diff), where ' diff exim4.conf /etc/exim4/ 'is the same as ' diff exim4.conf /etc/exim4/exim4.conf '. As asysadmin, I routinely diff versions of configuration files to dothings like verify that my intended new changes are actually theonly changes, so this feature routinely saves me from having torepeat the file name.
Linux distributions have sensible reasons to prefer periodic releases
In an aside in my entry on why Fedora version upgrades are a painfor me , I said that there are sensible reasonsfor for distributions doing periodic releases instead of 'rollingreleases'. Today I want to talk about some of them.
To start with, pretty much every major Linux distribution practicessome kind of rolling development (I don't count Red Hat Enterprisehere). No one does a release then goes away to do other things fora year or three before they start putting together the next one
Link: Old-School Disk Partitions
Warner Losh's Old-School Disk Partitions ( via )is a discussion of how disk partitioning worked and evolved in theearly days of Unix, up through 4.3 BSD. This has more informationthan what I wrote about how major and minor device numbers workedin V7 , because I missed that variousdisk device drivers had their own partitioning tables for minornumbers.
Warner Losh's blog has a lot ofinteresting writing on historical Unix things, so if that's oneof your interests (as
Solid state disks in mirrors and other RAID setups, and wear lifetimes
Writing down my plans to move to all solid state disks on my homemachine , where I don't have great backups,has made me start thinking about various potential issues that thisshift might create. One of them is specific to how I'm going to beusing my drives (and how I'm already using SSDs), which is inmirrored pairs and more generally in a RAID environment.
The theory of using mirrored drives is that it creates redundancyand gives you insurance against single disk drive failures
Web page generation systems should support remapping external URLs
Some web pages and web sites are hand authored, but many more aregenerated (dynamically or statically) through web page generationsystems and content management systems of various sorts. Also, oftenour writing in these systems has links to external pages; to otherpeople's writing, to reference documentation, to Wikipedia, towhatever. This presents us (the people running web sites and writingon them) a long term problem, because in practice some or manyof those external URLs will eventually change .
Today, we
A thought about the lifetimes of hard disks and solid state disks
At work, a related group to ours just had a SSD start reaching its official total writes lifetime,and this sparked a thought (especially when combined with my goalof moving away from hard drives on my own machine ).
On the one hand, it's increasingly conventional wisdom that modernsolid state drives (both SSD and NVMe) have a longer expectedlifetime on average than hard drives. On the other hand, you canget lucky and have individual hard drives that just keep on goingand going and going
Firefox is improving its handling of HTTP Basic Authentication (on Unix)
We're big users of HTTP Basic Authentication ,and I use Firefox (and what is effectively Firefox Nightly). RecentlyI noticed a nice little quality of life improvement in FirefoxNightly's handling of HTTP Basic Authentication, at least for peopleon Unix.
(I haven't tried to check how Firefox on Windows handles HTTPBasic Authentication, either in released versions or in Nightly.)
Today, if you go to a website that requires HTTP Basic Authenticationwith even the very latest Firefox 81.0
Using DMARC information is complicated in practice in the real world
As part of a planned switch to rspamd asour anti-spam system (well, our spam recognition system), I've beentaking a closer look at how our test rspamd scores some email andwhat it reports about why. This has given me a new and unhappy viewof DMARC in the real world,building on how DKIM looks for our 'good' email . So let me tell you a story, startingwith the background.
The university is now a big user of Microsoft Teams .The university
People still use newgrp (to my surprise)
One of the things that came out of me writing about why newgrp exists and casually mentioning that it was arelic (and that OpenBSD had gotten rid of it) is that a number ofpeople left comments discussing how they actively use newgrp eventoday. This surprised me more than a bit, although in retrospect itprobably shouldn't have.
There's long been an aphorism in software development that if youhave a large and complicated program (such as a word processor),80% of the people