Notes and gleanings.
- journalctl -k quietly means 'this boot only'2026-06-04
journalctl -k implies -b, so a --since window over kernel logs silently shows only the current boot.
- Why signed (x*2)/2 folds to x but unsigned doesn't2026-06-04
The same expression optimizes to a constant for signed ints and to real work for unsigned — because signed overflow is undefined, and one IR flag says so.
- d.get(k, default) is not d.get(k) or default2026-06-03
The two forms answer different questions; "or default" fires on every falsy stored value, not on a missing key.
- which bash startup file runs, and when2026-06-02
Login, interactive, and non-interactive bash each read different startup files — and ssh host cmd reads almost none of them.
- x is None, not x == None (and NaN isn't equal to itself)2026-06-01
In Python use is for the singletons and == for values — and remember that NaN never compares equal to itself.