add update script

this bash script will download a new version, if any, and exrtact it to
a temporary location. Then copy the new files to the current directory
and restart the systemd service.

scripts/upgrade-server.sh

@@ -0,0 +1,88 @@
+#! /bin/bash
+###############################################################################
+##											writefreely update script														 ##
+##																																					 ##
+##		WARNING: running this script will overwrite any modifed assets or 		 ##
+##		template files. If you have any custom changes to these files you 		 ##
+##		should back them up FIRST.																						 ##
+##																																					 ##
+##		This must be run from the web application root directory							 ##
+##		i.e. /var/www/writefreely, and operates under the assumption that you  ##
+##		have not installed the binary `writefreely` in another location.			 ##
+###############################################################################
+#
+#			Copyright © 2019 A Bunch Tell LLC.
+#
+#			This file is part of WriteFreely.
+#
+#			WriteFreely is free software: you can redistribute it and/or modify
+#			it under the terms of the GNU Affero General Public License, included
+#			in the LICENSE file in this source code package.
+#
+
+
+# only execute as root, or use sudo
+
+if [[ `id -u` -ne 0 ]]; then
+	echo "You must login as root, or execute this script with sudo"
+	exit 10
+fi
+
+# go ahead and check for the latest release on linux
+echo "Checking for updates.."
+
+url=`curl -s https://api.github.com/repos/writeas/writefreely/releases/latest | grep 'browser_' | grep linux | cut -d\" -f4`
+
+# check current version
+
+current=`./writefreely -v`
+
+echo "Current version is v${current:(-5):5}"
+
+# grab latest version number
+IFS='/'
+read -ra parts <<< "$url"
+
+latest=${parts[-2]}
+echo "Latest release is $latest"
+
+
+IFS='.'
+read -ra cv <<< "${current:(-5):5}"
+read -ra lv <<< "${latest#v}"
+
+IFS=' '
+tempdir=$(mktemp -d)
+
+
+if [[ ${lv[0]} -gt ${cv[0]} ]]; then
+	echo "New major version"
+	echo "Downloading.."
+	`wget -P $tempdir -q --show-progress $url`
+elif [[ ${lv[0]} -eq ${cv[0]} ]] && [[ ${lv[1]} -gt ${cv[1]} ]]; then
+	echo "New minor version"
+	echo "Downloading.."
+	`wget -P $tempdir -q --show-progress $url`
+elif [[ ${lv[2]} -gt ${cv[2]} ]]; then
+	echo "New patch version"
+	echo "Downloading.."
+	`wget -P $tempdir -q --show-progress $url`
+else
+	echo "Nothing to change"
+	exit 0
+fi
+
+filename=${parts[-1]}
+
+# extract
+echo "Extracing files.."
+tar -zxf $tempdir/$filename -C $tempdir
+
+# copy files
+echo "Copying files.."
+cp -r $tempdir/{pages,static,templates,writefreely} .
+
+# restart service
+echo "Restarting writefreely systemd service.."
+`systemctl restart writefreely`
+echo "Done, version has been upgraded to $latest."