Ok, I think this is officially a whine and a badge of shame.
I used to be pretty apt with scripting of various types (awk, sed, perl, php, etc) and even some light coding. However, I was playing around yesterday (with different distros/themes for KDE) and I decided to see how much difference there was in the installed packages on CachyOS and a vanilla Arch (themed with DarkXero’s scripts (https://wiki.xerolinux.xyz)). I hadn’t seen his stuff for a couple of years and actually am finding I miss/like it, so toying with idea of trying it on a VM with Cachyos.
As a first step, I installed a vanilla Arch setup on a spare drive, then ran his scripts to make sure they were working and up to date (they seem to be or at least produced an expected result). Then I was curious to get a diff of the packages installed on both systems. THAT was where I had this (whatever the opposite of epiphany is), when I realized I couldn’t remember how to script out what I wanted to do. It has frankly been most of ten years since I did anything more than mildly productive. So, greps, diffs, comps, awks later…I still don’t have what I wanted.
Then finally some long dormant brain cells awoke or were outside stimulated, and I realized I could get what I wanted by combining the files, sorting them, then run uniq -u on the result. This should NOT have taken me an hour to do.
Is this just way out of practice? Or is this, I’m old and I can’t think any more? I don’t know…maybe some of both.
lol i think it’s bit of both.
i take myself for example , i’m old and tired , yet at work they wanna teach me new stuff and after a course ,i never use it again . So couple months later when i’m suppose to do what this course taught me , i have no friggin clue … 
In my opinion , if you don’t do it everyday , over time you’ll “forget” .
In your decrepit state, daily practice is required. I suggest getting up at 5am every day, going for a 30 minute run, followed by 30 minutes of coding 
Hah, umm, I got you there…I got up at 10:45 pm (after going to bed on dull rainy evening at 6), however, due to rain, no running was (or likely to ever be…early morning strenuous activity causes hurling) accomplished due to rain. A walk during the daylight hours is good for me and enjoyable though:)
Yeah, totally messed up…time wise, sleep wise, etc.
I then DID spend over an hour pummeling defunct brain organ though.
I much prefer this to running.
I suppose it’s “confusion” 
, although there is apophany [1] as well.
I’ve tried some c-programming some time ago, after not having done so for 30+ years. I found that I had forgotten a lot. A lot, I tell you…
Still, I wanted to get some program running which C was best suited for, so, I tried what I used to do: just doggedly tinker along, find and read the information as and when needed, try it out, and learn whilst doing.
I then found that I had trouble to just put the effort in to try and recall the knowledge either from memory of from reading up online. Reading information and then understanding it and putting it to good use appeared to be so much more difficult than I remember it being.
Also I found that my brain is not good with details anymore. The bigger picture, the general idea, the basic concepts, yes, no problem, but the underlying details, the nitty gritty, no, not really, too tiring somehow.
I am, however, able to recall quite a lot of “useless” facts that used to be useful, like specific memory addresses in my first home PC, postal area code of the house I was born in, a couple of paragraphs of Hamlet which I learned when I was a teenager, and the names of people I have not spoken to for 50 years.
But please don’t ask me what I had for dinner yesterday.
You describe me so well, even though we’ve never met lol.