sudo debootstrap --no-merged-usr stable /container/1 # get a root file system
unshare --mount --uts --ipc --net --fork --user --map-root-user /bin/bash
chroot /container/1 /bin/bash
unshare --pid --fork /bin/bash # Just to have PID=1
mount -t proc none /proc
mount -t sysfs none /sys
mount -t tmpfs none /tmp

$ unshare --fork --user --map-root-user
# debootstrap stable /container/2
mknod: /home/mocc/test2/test-dev-null: Operation not permitted
E: Cannot install into target '/home/mocc/test2' mounted with noexec or nodev