Add script for OpenBSD remote backups

bin/Makefile

@@ -15,7 +15,7 @@
 PREFIX =	$(HOME)
 MANPREFIX =	$(PREFIX)/local
 BIN =		ZZZ browser credentials fetch flac2ogg imgresize invidious \
-		nyaasearch plumb pstsrv rfcopen screenshot sekrit \
+		nyaasearch plumb pstsrv rbucmd rfcopen screenshot sekrit \
 		w3m-copy-link
 MAN1 =		sekrit.1
 BROWSER_LINKS =	tor-browser

bin/rbucmd.sh

@@ -0,0 +1,74 @@
+#!/bin/sh
+# env
+# Written in 2021 by Lucas
+# CC0 1.0 Universal/Public domain - No rights reserved
+#
+# To the extent possible under law, the author(s) have dedicated all
+# copyright and related and neighboring rights to this software to the
+# public domain worldwide. This software is distributed without any
+# warranty. You should have received a copy of the CC0 Public Domain
+# Dedication along with this software. If not, see
+# <http://creativecommons.org/publicdomain/zero/1.0/>.
+
+usage()
+{
+	printf "Usage: %s [-c] [-l login_name] host backup-name\n" \
+	    "${0##*/}" >&2
+	exit 1
+}
+
+err()
+{
+	printf "%s: %s\n" "${0##*/}" "$*" >&2
+	exit 1
+}
+
+login_name=$(id -nu)
+agent_mode=yes
+while getopts cl: flag; do
+	case $flag in
+	c)	agent_mode=confirm ;;
+	l)	login_name=$OPTARG ;;
+	*)	usage
+	esac
+done
+shift $((OPTIND - 1))
+if [ $# -ne 2 ] || [ -z "$1" ] || [ -z "$2" ]; then
+	usage
+fi
+host=$1
+backup_name=$2
+
+[ -f "$host/bulist" ] || err "no bulist present in \"$h/\""
+
+eval $(ssh-agent -s)
+trap 'eval $(ssh-agent -ks)' EXIT INT QUIT TERM
+
+set -e
+
+# Load correct key into ssh-agent.
+ssh -o AddKeysToAgent=$agent_mode "$login_name@$host" true
+
+cd "$host"
+tmpdir=$(ssh "$login_name@$host" mktemp -dt rbucmd.XXXXXX)
+
+sftp "$login_name@$host" <<EOF
+put bulist $tmpdir/bulist
+EOF
+
+ssh "$login_name@$host" "cat - >\"$tmpdir/bu.sh\"" <<EOF
+cd / &&
+    pkg_info -mz >/tmp/pkg-info.txt &&
+    doas xargs pax -wzf "$tmpdir/$backup_name.tgz" <"$tmpdir/bulist" &&
+    doas chown "$login_name:$login_name" "$tmpdir/$backup_name.tgz"
+EOF
+
+# -t is needed for doas to read a password.
+ssh -t "$login_name@$host" sh "$tmpdir/bu.sh"
+
+sftp -o "user=$login_name" "$host" <<EOF
+get $tmpdir/$backup_name.tgz
+rm $tmpdir/*
+rmdir $tmpdir/
+rm /tmp/pkg-info.txt
+EOF