A place to keep track of things I’ve learned. Inspired by Simon Willison’s TILs.
All thoughts, opinions, etc. expressed herein are strictly my own and not of my employer’s.
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Perl 5 went through a long nadir of unpopularity due in large part to its deserved “Write Once, Read Never” reputation. So I was surprised to find out not only is it installed by default on Debian, it’s installed nearly everywhere by default. It’s even the non-shell scripting language of choice on OpenBSD! Perhaps the only thing more impressive than Perl’s utter ubiquity is its longevity. The latest major version of Perl was first released in 1994....
Below is a GIF of tsk, my pocket Finnish-to-English dictionary, running in my terminal emulator of choice under Linux. It’s what the kids call a TUI, a graphical program that just happens to drive its graphics using terminal graphics instead of graphics-graphics. Insert GIF here. You can probably tell that this program fits neatly into the “home-cooked meal” clade of programs. There is a very straightforward problem I want solved - fast, single-executable-portable dictionary lookup, with a few conveniences for the busy language learner layered on top....
Peanut butter and jelly are complementary goods, as are cars and gasoline, newer cars and electricity, electricity and basically everything else. We don’t normally think of, say, Docker and Kubernetes as complementary goods in software engineering, because you can get both for the low price of free. Or can you? You still have to invest time in learning both, and as the famous saying goes… Say it takes X hours to learn Docker adequately....
If you followed “Binary search isn’t about search” and “Binary search isn’t about search II” properly, the following statements should suffice as a summary: 1 2 L[0:l] < T < L[r:len(L)] # ordinary binary search loop invariant L[0:l] < T <= L[r:len(L)] # leftwise binary search loop invariant Let’s complete the triptych. Take a wild guess what invariant we use for rightmost element binary search: 1 L[0:l] <= T < L[r:len(L)] # rightwise binary search loop invariant A motivating example Consider again an array like...
In the first “Binary search isn’t about search” post, we spoke about using assert statements to enforce your loop invariants. Our plain old everyday binary search invariant can be summarized as such: For all x in L[0:l]1, x is strictly less than T, the element we are searching for. For all y in L[r:len(L)]2, y is strictly greater than T, the element we are searching for. Or, if we want to be even terser, we could note this as simply...
Suppose you’re trying to track down a bug that appeared in a series of Git commits. You’ve been idly keeping track of where this bug appears in your lucky commits by hand, while busy with other things. So far you’ve compiled this table: 1 2 3 4 5 6 7 8 9 10 0000000 🧼 clean, no bug. 0000001 🧼 0000002 🧼 0000003 🧼 0000004 🧼 0000005 🧼 0000006 🐛 bug first appears here....
Before I moved to Finland, I spent some time in the Hobbesian war of all against all that is Wisconsin1. Men were men back in that less civilized age, and “cybersecurity” a ninny-word dreamt up by social harmony types who honestly thought they had anything worth stealing in their servers. For those of us doing real work, which I must emphasize you should never do, we had Expect. And to SSH automatically into servers where we didn’t have fancy accoutrements like “keys” or “audit requirements”, we did stuff like...
This is a response to pid1.call’s “Siren Call of SQlite on the Server”, which itself is a response to articles like Wesley Aptekar-Cassels’s “Consider SQLite” espousing SQLite as a server-side technology. Cards on the table, I both love SQLite and think pid1 has the more correct take here. When I decided on a dime after college to move countries and be with my wife, part of the package deal was that I had to throw away my dreams of easing into the software industry by resting on the laurels of my strong, but not MIT-level-known-worldwide-strong, alma mater (sorry Wildcats)....
Ever need to download a file from a server – or get someone else to download a file from a server, who may not be comfortable with or should have access to scp or sftp? Turns out, if you have Python installed – and you probably do – it comes with a handy one-liner file server for just such an occasion: 1 python -m http.server 12345 # or whatever port you prefer Then to close the server, just Ctrl+C....
Last night I went to DigitalOcean and spun up a tiny new, $4/month droplet – on my own dime! It sounds crazy, but I’ve never actually wanted to pay for hosting myself before. But I have a fun little web app cooking up, one that might eventually pay that $4/month back with interests, and I decided, why not, it’s time to finally put some of my own skin in the game with this whole sysadmin thing....