Let's bootstrap Arch Linux from BASH:
$ curl -\# https://mirrors.kernel.org/archlinux/iso/latest/archlinux-bootstrap-$(date +%Y.%m.01)-$(uname -m).tar.gz | tar xz --strip-components 1 -C '/path/to/install/directory'
Wait, hold on. Hold on a second.
Yep, you can actually bootstrap one of the world's largest distros with a oneliner.
Alternatively, you can use archbootstrap:
$ archbootstrap ./arch
# archbootstrap /var/lib/machines/arch
archbootstrap will cache downloaded files in $XDG_CACHE_HOME or $HOME/.cache if run as a user, and in /var/cache if run as root.
archbootstrap supports some options:
$ archbootstrap -h
usage: archbootstrap [options] root
-a <arch>
-c <cachedir>
-h help
-i show post-install ideas
-m <mirror>
-n no-cache