How to (really) restore legacy behavior of `su` in Debian Buster

From https://wiki.debian.org/NewInBuster: The su command in buster is provided by the util-linux source package, instead of the shadow source package, and no longer alters the PATH variable by default. This means that after doing su, your PATH may not contain directories like /sbin, and many system administration commands will fail. There are several workarounds: Use Read More …