To keep on working on my new system via my already established (legacy) system, it would be useful to have the manjaro-chroot running on my legacy system. The arch-chroot package is part of the arch-install-scripts. So where to find the manjaro-chroot package? It doesn’t seem to be in the repos. There is only a manjaro-chrootbuild, but I think its purpose differs from my needs.
It does more than that. It also mounts all of the pseudo-filesystems — i.e. /proc, /sys, /dev, et al — and, if the system boots in native UEFI mode, /boot/efi.
Note:manjaro-chroot was designed to work in combination with ext4 (or similarly traditional filesystems) only. It does not work in combination with btrfs.
Because it wasn’t already installed, the command you needed was:
pacman -F manjaro-chroot
# or update the database first
sudo pacman -Fy manjaro-chroot
# you can also specify the path to narrow it down
pacman -F /usr/bin/manjaro-chroot