bin/isabelle-process

   echo
   echo "  Options are:"
   echo "    -C           tell ML system to copy output image"
   echo "    -I           startup Isar interaction mode"
   echo "    -P           startup Proof General interaction mode"
+  echo "    -S           secure mode -- disallow critical operations (e.g. ML evaluation)"
   echo "    -X           startup PGIP interaction mode"
   echo "    -c           tell ML system to compress output image"
   echo "    -e MLTEXT    pass MLTEXT to the ML session"
   echo "    -f           pass 'Session.finish();' to the ML session"
   echo "    -m MODE      add print mode for output"

 # options
 
 COPYDB=""
 ISAR=false
 PROOFGENERAL=""
+SECURE=""
 COMPRESS=""
 MLTEXT=""
 MODES=""
 TERMINATE=""
 READONLY=""
 NOWRITE=""
 
-while getopts "XCIPce:fm:qruw" OPT
+while getopts "XCIPSce:fm:qruw" OPT
 do
   case "$OPT" in
     C)
       COPYDB=true
       ;;
     I)
       ISAR=true
       ;;
     P)
       PROOFGENERAL=true
+      ;;
+    S)
+      SECURE=true
       ;;
     X)
       PGIP=true
       ;;
     c)

 
 ML_SYSTEM_BASE=$(echo "$ML_SYSTEM" | cut -f1 -d-)
 
 [ -n "$MODES" ] && MLTEXT="print_mode := [$MODES]; $MLTEXT"
 
+[ -n "$SECURE" ] && MLTEXT="$MLTEXT Secure.set_secure ();"
+
 if [ -n "$PGIP" ]; then
   MLTEXT="$MLTEXT; ProofGeneral.init_pgip $ISAR;"
 elif [ -n "$PROOFGENERAL" ]; then
   MLTEXT="$MLTEXT; ProofGeneral.init $ISAR;"
 elif [ "$ISAR" = true ]; then