In the Debian wiki.
debootstrap beowulf /tmp/target http://deb.devuan.org/merged
Fix up fstab and mount /proc, /sys of type proc and sysfs
/etc/hostname
/etc/hosts
/etc/network/interfaces
/etc/resolv.conf
Install mdadm if the base system is intended for a root file system on a RAID array
Set a password for root or add a normal user
See debootstrap vs installation.
chroot: failed to run command 'dpkg-deb': No such file or directory
I got this when using http://deb.devuan.org/devuan instead of ../merged.