For embedded systems, avoid BusyBox’s su altogether. Use sudo or a dedicated su binary from a standard package. If you must use BusyBox, ensure the su applet runs with SUID – but be aware of the security trade-offs. Have you seen this error in the wild? The fix is usually a single chmod u+s or an apk add util-linux . Just remember: with great power (SUID) comes great responsibility.
# As root chmod u+s /bin/busybox But this makes BusyBox command run as root when executed via the busybox binary – a security nightmare. busybox su must be suid to work properly
Ensure the correct su is first in your PATH . Typically: For embedded systems, avoid BusyBox’s su altogether