The embedded people will naturally look at busybox. I saw it running on a credit card scanner at Old Navy a few years ago. It has an init: $ /home/busybox-1

The embedded people will naturally look at busybox. I saw it running on a credit card scanner at Old Navy a few years ago. It has an init: $ /home/busybox-1.35 init --help BusyBox v1.35.0 (2022-01-17 19:57:02 CET) multi-call binary. Usage: init Init is the first process started during boot. It never exits. It (re)spawns children according to /etc/inittab. Signals: HUP: reload /etc/inittab TSTP: stop respawning until CONT QUIT: re-exec another init USR1/TERM/USR2/INT: run halt/reboot/poweroff/Ctrl-Alt-Del script On an embedded system, that will be a strong contender for pid 1.