Added version checking to help non-git users

CHECKUPDATE=yes (the default) will now alert you if there is a new
version available of this tool.

Solves #135

README.md

@@ -44,6 +44,8 @@ You can point out a different file than ```.plexupdate``` by providing it as the
 
 There are also a few additional options for the more enterprising user. Setting any of these to `yes` will enable the function.
 
+- CHECKUPDATE
+  If set (and it is by default), it will compare your local copy with the one stored on github. If there is any difference, it will let you know. This is handy if you're not using ```git clone``` but want to be alerted to new versions.
 - PLEXSERVER
   If set, and combined with AUTOINSTALL, the script will automatically check if the server is in-use and defer the update. Great for crontab users. PLEXSERVER should be set to the IP/DNS of your Plex Media Server, which typically is 127.0.0.1
 - PLEXPORT

plexupdate.sh

@@ -7,9 +7,14 @@
 # as well as the PlexPass versions.
 #
 # PlexPass users:
-#   Either modify this file to add email and password OR create
-#   a separate .plexupdate file in your home directory with these
-#   values.
+#   Create a separate .plexupdate file in your home directory with these
+#   values:
+#
+#   EMAIL='<whatever your plexpass email was>'
+#   PASS='<whatever password you used>'
+#   DOWNLOADDIR='<where you would like to save the downloaded package>'
+#
+# See https://github.com/mrworf/plexupdate for more details.
 #
 # Returns 0 on success
 #         1 on error
@@ -118,9 +123,9 @@ ALLARGS="$@"
 infoLog "Args: ${ALLARGS}" >/dev/null
 unset ALLARGS
 
-####################################################################
-# Set these three settings to what you need, or create a .plexupdate file
-# in your home directory with this section (avoids changing this).
+#################################################################
+# Don't change anything below this point, use a .plexupdate file
+# in your home directory to override this section.
 # DOWNLOADDIR is the full directory path you would like the download to go.
 #
 EMAIL=
@@ -129,10 +134,6 @@ DOWNLOADDIR="."
 PLEXSERVER=
 PLEXPORT=32400
 
-#################################################################
-# Don't change anything below this point
-#
-
 # Defaults
 # (aka "Advanced" settings, can be overriden with config file)
 FORCE=no
@@ -148,6 +149,7 @@ ARCH=$(uname -m)
 IGNOREAUTOUPDATE=no
 SHOWPROGRESS=no
 WGETOPTIONS=""	# extra options for wget. Used for progress bar.
+CHECKUPDATE=yes
 
 # Default options for package managers, override if needed
 REDHAT_INSTALL="yum -y install"
@@ -162,6 +164,8 @@ FILE_SHA=$(mktemp /tmp/plexupdate.sha.XXXX)
 FILE_WGETLOG=$(mktemp /tmp/plexupdate.wget.XXXX)
 FILE_CMDLOG=$(mktemp /tmp/plexupdate.cmds.XXXX)
 FILE_CMDERR=$(mktemp /tmp/plexupdate.errs.XXXX)
+FILE_LOCAL=$(mktemp /tmp/plexupdate.local.XXXX)
+FILE_REMOTE=$(mktemp /tmp/plexupdate.remote.XXXX)
 
 # Current pages we need - Do not change unless Plex.tv changes again
 URL_LOGIN=https://plex.tv/users/sign_in.json
@@ -380,7 +384,7 @@ done
 if [ "${SAVECONFIG}" = "yes" ]; then
 	echo "# Config file for plexupdate" >${CONFIGFILE:="${HOME}/.plexupdate"}
 
-	for VAR in AUTOINSTALL CRON AUTODELETE DOWNLOADDIR EMAIL PASS FORCE FORCEALL PUBLIC QUIET AUTOSTART AUTOUPDATE PLEXSERVER PLEXPORT
+	for VAR in AUTOINSTALL CRON AUTODELETE DOWNLOADDIR EMAIL PASS FORCE FORCEALL PUBLIC QUIET AUTOSTART AUTOUPDATE PLEXSERVER PLEXPORT CHECKUPDATE
 	do
 		if [ ! -z ${!VAR} ]; then
 
@@ -572,9 +576,35 @@ function cleanup {
 	rm "${FILE_WGETLOG}" 2>/dev/null >/dev/null
 	rm "${FILE_CMDLOG}" 2>/dev/null >/dev/null
 	rm "${FILE_CMDERR}" 2>/dev/null >/dev/null
+	rm "${FILE_LOCAL}" 2>/dev/null >/dev/null
+	rm "${FILE_REMOTE}" 2>/dev/null >/dev/null
 }
 trap cleanup EXIT
 
+if [ "${CHECKUPDATE}" = "yes" ]; then
+	ERR1=0
+	(wget -q https://raw.githubusercontent.com/mrworf/plexupdate/master/plexupdate.sh -O - 2>/dev/null || echo ERROR) | shasum >"${FILE_REMOTE}" 2>/dev/null
+	ERR2=0
+	(cat "$0" 2>/dev/null || echo ERROR) | shasum >"${FILE_LOCAL}" 2>/dev/null
+	if [ $ERR1 -ne 0 -o $ERR2 -ne 0 ]; then
+		errorLog "CheckUpdate: Unable to confirm version of script"
+	else
+		# "709c7506b17090bce0d1e2464f39f4a434cf25f1" is the hash for "ERROR" :)
+		if grep -sq "709c7506b17090bce0d1e2464f39f4a434cf25f1" "${FILE_LOCAL}" ; then
+			errorLog "CheckUpdate: Unable to validate local copy"
+		elif grep -sq "709c7506b17090bce0d1e2464f39f4a434cf25f1" "${FILE_REMOTE}" ; then
+			errorLog "CheckUpdate: Unable to validate remote copy"
+		elif ! diff "${FILE_LOCAL}" "${FILE_REMOTE}" >/dev/null 2>/dev/null ; then
+			infoLog "Newer version of this script is available at https://github.com/mrworf/plexupdate"
+			infoLog "(or you've made changes to this script yourself)"
+		fi
+	fi
+	rm "${FILE_LOCAL}" 2>/dev/null >/dev/null
+	rm "${FILE_REMOTE}" 2>/dev/null >/dev/null
+fi
+
+
+
 # Fields we need to submit for login to work
 #
 # Field			Value