OpenBSD release, syspatch and snapshot downloader script

openbsd-release-downloader.sh

#!/bin/ksh

## downloads OpenBSD releases, snapshots and syspatches, and verifies them
## with signify(1). Files are downloaded to /var/www/htdocs/OpenBSD/... per
## the standard mirror layout, so that you can use them as an installurl.
##
## I use this to retrieve sets for building VMs.
##
## upstream mirror is selected from /etc/installurl.
##
## You will probably not have a good time running this on non-OpenBSD hosts
## due to the use of signify(1).
##
## options:
##
##   -m   specify the architecture, eg. -m amd64   (default: host architecture)
##   -r   specify a release, eg. -s 7.4            (default: host release)
##   -p   download syspatches instead
##   -s   download the latest snapshot instead

set -eu

arch=$(uname -m)
release=$(uname -r)
syspatch=no

while getopts m:pr:s flag ; do
	case $flag in
		m) arch="$OPTARG" ;;
		r) release="$OPTARG" ;;
		s) release="snapshots" ;;
		p) syspatch=yes ;;
		*) echo "USAGE: $0 [-m ARCH] [-r RELEASE]|[-s]|[-p]" >&2 ; exit 1 ;;
	esac
done

if [[ "$syspatch" = "yes" ]] ; then
	downloadbase="$(cat /etc/installurl)/syspatch/$release/$arch"
	releasepath="/var/www/htdocs/pub/OpenBSD/syspatch/$release/$arch"
else
	downloadbase="$(cat /etc/installurl)/$release/$arch"
	releasepath="/var/www/htdocs/pub/OpenBSD/$release/$arch"
fi

mkdir -p "$releasepath"
cd "$releasepath"

ftp -V "$downloadbase/SHA256.sig"
awk \
	-v downloadbase="$downloadbase" \
	-F'[() ]+' \
	'$1 == "SHA256" { print downloadbase "/" $2 }' \
	SHA256.sig \
	| xargs -n1 -P10 ftp -V

signify -C -x SHA256.sig