Primary symptom: /proc/self/fd is there and normally populated, however /dev/fd is not. Process substitution therefore fails, because bash wants to create files under /dev/fd. /dev/.static/ and ...
I use Gentoo. I write a udev rule. localhost biergaizi # cat /etc/udev/rules.d/91-change-schduler.rules #SUBSYSTEMS=="usb", KERNEL=="sd??", ACTION=="add", RUN+="echo deadline > ...