tvheadend: fix tv_grab_file

tvheadend calls `tv_grab_file --description` to get a description of the grabber. If the grabber doesn't return a string, tvheadend will not use the grabber.

packages/addons/service/tvheadend/source/bin/tv_grab_file

@@ -18,6 +18,8 @@
 #  along with OpenELEC.  If not, see <http://www.gnu.org/licenses/>.
 ################################################################################
 
+if [ $# -lt 1 ]
+then
   . /etc/profile
 
   ADDON_HOME="$HOME/.kodi/userdata/addon_data/service.multimedia.tvheadend"
@@ -38,3 +40,30 @@ elif [ "$XMLTV_TYPE" = "WEB" ]; then
     wget -qO - "$XMLTV_LOCATION_WEB"
     exit 0
   fi
+fi
+
+dflag=
+vflag=
+cflag=
+
+for a in "$@"
+do
+[ "$a" = "-d" -o "$a" = "--description"  ] && dflag=1
+[ "$a" = "-v" -o "$a" = "--version"      ] && vflag=1
+[ "$a" = "-c" -o "$a" = "--capabilities" ] && cflag=1
+done
+
+if [ -n "$dflag" ]
+then
+echo "tv_grab_file is a simple grabber that can be configured through the addon settings from Kodi"
+fi
+
+if [ -n "$vflag" ]
+then
+echo "1.0"
+fi
+
+if [ -n "$cflag" ]
+then
+echo "baseline"
+fi