Suppose that you're writing Bourne shell code that involves usingsome commands in a subshell to capture some information into a shellvariable, 'AVAR=$(....)', but you accidentally write it with a spaceafter the '='. Then you will get something like this:

$ AVAR= $(... | wc -l)sh: 107: command not found

So, why is this an error at all, and why do we get this weird and

As I mentioned recently , I recentlyhad an extended outage on my home Internet. When my Internet cameback, it was a little bit different. My old home Internet was DSLwith 14 Mbits down, 7 Mbits up, and about 7 milliseconds pings towork. The new state of my home Internet is still DSL from the sameprovider, but now it's 50 Mbits down, 4 Mbits up, and about 18milliseconds pings to work at the moment. When my Internet firstcame back

The ZFS ' recordsize ' property (on filesystems) is a famously confusing ZFS property that is more or less the maximumlogical block size of files on the filesystem. However, you'reallowed to change it even after the filesystem has been created,so this raises the question of what happens with existing fileswhen you do so. The simple answer is that existing files areunaffected and continue to use the old recordsize. The technicalanswer can be a lot more complicated, and to understand it I'm going

If and when you set out to traverse through a Unix directoryhierarchy, whether to inventory it or to find something, you havea decision to make. I can put this decision in technical terms,about whether you use stat() or lstat() when identifyingsubdirectories in your current directory, or put it non-technically,about whether or not you follow symbolic links that happen to pointto directories. As you might guess, there are two possible answershere and neither is unambiguously wrong (or right)

I am broadly a MFA (Multi-Factor Authentication) skeptic ( cf ) and as a resultI don't have much exposure to it. For reasons beyond the scope ofthis entry, I've recently been needing to understand more than usualabout how it works from the perspective of people using it, so hereis my current understanding of your generally available non-hardwareoptions that can be used in a desktop environment (security keysare out of scope).

There are three generally available and used approaches

In practice, ClamAV is both a virus andmalware recognition engine and a collection of malware signatures.ClamAV only comes with a limited set of signatures, so supplementingit with additional third party sources is popular (and perhapsalmost essential). Often people use update tools and scripts toconfigure and fetch these additional signatures, such as Fangfrisch . One of the popularproviders of third party signatures is Malware Patrol , who have a number of tiers ofaccess, including a (free) tier for educational institutions. Since we are

One of the things that people like to recommend for SSH authenticationis that instead of individual host and user keys that people haveto trust and manage one by one, you set up a SSH certificate authorityand trust it, with it signing user keys, host keys, or both. However,just like OpenSSH signed certificates aren't X.509 certificates , an OpenSSH 'certificate authority'is not like a traditional CA. This especially matters when it comesto the interesting question of whether or not you

For a long time, one of the pieces of advice for dealing with various TLS certificate problems is that you should establish your own internalCertificate Authority with its own CA root certificate, have yoursystems trust it, and then issue certificates from your internalCA with whatever names and other qualities you needed. My reactionto this suggestion has traditionally been that it was extremelydangerous. If your internal CA was compromised in some way you hadgiven an attacker the ability to impersonate anything, and generallyproperly operating a truly secure internal

One of the things I've become more and more aware of over time asI talk about our metrics, monitoring, and alerting system is that what 'alerts' are can varyquite a bit between environments, despite everyone using the sameterm and often the same technology to implement their particularform of 'alerts'. Some of the difference in what alerts mean istechnological and some of it is organizational (or 'operational').

The first big difference, which is partly technology (in how alertsare