$ ./start-ubuntu.sh
proot warning: can't chdir("/root/.") in the guest rootfs: No such file or directory
proot info: default working directory is now "/"
proot error: '/usr/bin/env' not found (root = /data/data/com.termux/files/home/termux-ubuntu/ubuntu-fs, cwd = /, $PATH=(null))
fatal error: see `proot --help`.
$