/usr/share/initramfs-tools/hooks/nbd is in nbd-client 1:2.9.25-2ubuntu1.
This file is owned by root:root, with mode 0o755.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 | #!/bin/sh
# We don't have any prerequirements
case $1 in
prereqs)
exit 0
;;
esac
. /usr/share/initramfs-tools/hook-functions
force_load nbd
auto_add_modules net
copy_exec /sbin/nbd-client /sbin
|