Fix Linux SLURL protocol handling

Known issue: May not work with Microsoft Edge Beta for Linux on some setups. Cause is unknown at the moment and requires further investigation.

indra/newview/linux_tools/register_secondlifeprotocol.sh

@@ -4,7 +4,7 @@
 # URLs of the form secondlife://...
 #
 
-desired_handler="$1"
+desired_handler="${1}"
 
 print() {
 	log_prefix="RegisterSLProtocol:"
@@ -56,9 +56,9 @@ fi
 #Check if xdg-mime is present, if so, use it to register new protocol.
 if command -v xdg-mime query default x-scheme-handler/secondlife >/dev/null 2>&1; then
 	urlhandler=$(xdg-mime query default x-scheme-handler/secondlife)
-	localappdir="$HOME/.local/share/applications"
+	localappdir="${HOME}/.local/share/applications"
 	newhandler="secondlifeprotocol_$(basename "$(dirname "${desired_handler}")").desktop"
-	handlerpath="$localappdir/$newhandler"
+	handlerpath="${localappdir}/${newhandler}"
 	cat >"${handlerpath}" <<EOFnew || print "Warning: Did not register secondlife:// handler with xdg-mime: Could not write $newhandler"s
 [Desktop Entry]
 Version=1.5
@@ -75,21 +75,21 @@ EOFnew
 	# TODO: use absolute path for the desktop file
 	# TODO: Ensure that multiple channels behave properly due to different desktop file names in /usr/share/applications/
 	# TODO: Better detection of what the handler actually is, as other viewer projects may use the same filename
-	if [ -z "$urlhandler" ]; then
+	if [ -z "${urlhandler}" ]; then
 		print No SLURL handler currently registered, creating new...
 	else
 		#xdg-mime uninstall $localappdir/$urlhandler
 		#Clean up handlers from other viewers
-		if [ "$urlhandler" != "$newhandler" ]; then
+		if [ "${urlhandler}" != "${newhandler}" ]; then
 			print "Current SLURL Handler: ${urlhandler} - Setting ${newhandler} as the new default..."
-			mv "$localappdir"/"$urlhandler" "$localappdir"/"$urlhandler".bak
+			mv "${localappdir}"/"${urlhandler}" "${localappdir}"/"${urlhandler}".bak
 		else
 			print "SLURL Handler has not changed, leaving as-is."
 		fi
 	fi
-	xdg-mime default $newhandler x-scheme-handler/secondlife
+	xdg-mime default ${newhandler} x-scheme-handler/secondlife
 	if command -v update-desktop-database >/dev/null 2>&1; then
-		update-desktop-database "$localappdir"
+		update-desktop-database "${localappdir}"
 		print "Registered ${desired_handler} as secondlife:// protocol handler with xdg-mime."
 	else
 		print "Warning: Cannot update desktop database, command missing - installation may be incomplete."