diff --git a/planning/src/RS/rsOpts.cpp b/planning/src/RS/rsOpts.cpp
index 7cfe4dd1..6e560947 100644
--- a/planning/src/RS/rsOpts.cpp
+++ b/planning/src/RS/rsOpts.cpp
@@ -203,45 +203,69 @@ static char* make_file_name(CStr arg) noexcept {
 void rsOpts::setFunction(CStr fun) noexcept {
   function_ = nullptr;
   if (!fun) return;
+
+  uint16_t tr = ltrace();
+
   static CStr s_funList[] = {"cmd",        // 0
                              "pinc",       // 1
                              "stars",      // 2
                              "partition",  // 3
                              "pack",       // 4
                              "route",      // 5
+                             "shell",      // 6
                              nullptr};
   string f = str::s2lower(fun);
   if (f.empty()) return;
   if (f == "cmd") {
     function_ = s_funList[0];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
     assert(is_fun_cmd());
     return;
   }
   if (f == "pin" or f == "pinc" or f == "pin_c") {
     function_ = s_funList[1];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
     assert(is_fun_pinc());
     return;
   }
   if (f == "sta" or f == "star" or f == "stars") {
     function_ = s_funList[2];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
     assert(is_fun_stars());
     return;
   }
   if (f == "par" or f == "part" or f == "partition") {
     function_ = s_funList[3];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
     assert(is_fun_partition());
     return;
   }
   if (f == "pac" or f == "pack" or f == "packing") {
     function_ = s_funList[4];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
     assert(is_fun_pack());
     return;
   }
   if (f == "rt" or f == "route" or f == "routing") {
     function_ = s_funList[5];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
     assert(is_fun_route());
     return;
   }
+  if (f == "sh" or f == "SH" or f == "shell" or
+      f == "shel" or f == "Shell") {
+    function_ = s_funList[6];
+    if (tr >= 5)
+      lprintf("Opts::setFunction: %s\n", function_);
+    assert(is_fun_shell());
+    return;
+  }
 }
 
 bool rsOpts::is_arg0_pinc() const noexcept {
diff --git a/planning/src/RS/rsOpts.h b/planning/src/RS/rsOpts.h
index 32564dbf..13eb50bd 100644
--- a/planning/src/RS/rsOpts.h
+++ b/planning/src/RS/rsOpts.h
@@ -3,6 +3,9 @@
 #define __pln_Opts_H__e91c943c16c2d_
 
 #include "util/pln_log.h"
+#include <bitset>
+
+#undef MAX_UNITS
 
 namespace pln {
 
@@ -12,30 +15,39 @@ using CStr = const char*;
 
 struct rsOpts {
 
+  static constexpr uint MAX_UNITS = 64;
+
   CStr shortVer_ = nullptr;
 
   int argc_ = 0;
   const char** argv_ = nullptr;
 
-  CStr function_ = nullptr; // {cmd, pinc, stars, partition, pack, route}
+  CStr function_ = nullptr; // {cmd, pinc, stars, partition, pack, route, shell}
   bool have_function() const noexcept { return function_; }
+  bool function_is(CStr x) const noexcept {
+    if (!x) return !function_;
+    return function_ and ::strcmp(function_, x) == 0;
+  }
   bool is_fun_cmd() const noexcept {
-    return function_ && !strcmp(function_, "cmd");
+    return function_is("cmd");
   }
   bool is_fun_pinc() const noexcept {
-    return function_ && !strcmp(function_, "pinc");
+    return function_is("pinc");
   }
   bool is_fun_stars() const noexcept {
-    return function_ && !strcmp(function_, "stars");
+    return function_is("stars");
   }
   bool is_fun_partition() const noexcept {
-    return function_ && !strcmp(function_, "partition");
+    return function_is("partition");
   }
   bool is_fun_pack() const noexcept {
-    return function_ && !strcmp(function_, "pack");
+    return function_is("pack");
   }
   bool is_fun_route() const noexcept {
-    return function_ && !strcmp(function_, "route");
+    return function_is("route");
+  }
+  bool is_fun_shell() const noexcept {
+    return function_is("shell");
   }
   bool is_arg0_pinc() const noexcept;
   bool is_implicit_pinc() const noexcept;
@@ -74,13 +86,7 @@ struct rsOpts {
   bool check_ = false;
   bool cleanup_ = false;
 
-  bool unit1_ = false;
-  bool unit2_ = false;
-  bool unit3_ = false;
-  bool unit4_ = false;
-  bool unit5_ = false;
-  bool unit6_ = false;
-  bool unit7_ = false;
+  std::bitset<MAX_UNITS> units_;
 
   rsOpts() noexcept = default;
   rsOpts(int argc, const char** argv) noexcept { parse(argc, argv); }
@@ -92,13 +98,13 @@ struct rsOpts {
   void print(CStr label = nullptr) const noexcept;
   void printHelp() const noexcept;
 
-  bool unit_specified() const noexcept {
-    return unit1_ or unit2_ or unit3_ or unit4_ or unit5_ or unit6_
-           or unit7_;
-  }
+  bool unit_specified() const noexcept { return units_.any(); }
+
   bool ver_or_help() const noexcept { return version_ or det_ver_ or help_; }
 
-  bool trace_specified() const noexcept { return traceIndex_ > 0 and trace_ > 0; }
+  bool trace_specified() const noexcept {
+    return traceIndex_ > 0 and trace_ > 0;
+  }
   bool test_id_specified() const noexcept { return test_id_ > 0; }
 
   bool set_STA_testCase(int TC_id) noexcept;
diff --git a/planning/src/main.cpp b/planning/src/main.cpp
index b8b8bb7e..ee18dcd4 100644
--- a/planning/src/main.cpp
+++ b/planning/src/main.cpp
@@ -1,4 +1,4 @@
-static const char* _pln_VERSION_STR = "pln0363";
+static const char* _pln_VERSION_STR = "pln0364";
 
 #include "RS/rsEnv.h"
 #include "util/pln_log.h"
@@ -470,16 +470,20 @@ static void deal_help(const rsOpts& opts) {
 static void deal_units(const rsOpts& opts) {
 #ifdef PLN_UNIT_TEST_ON
   using namespace tes;
-  if (opts.unit1_) tes::run_U1();
-  if (opts.unit2_) tes::run_U2();
-  if (opts.unit3_) tes::run_U3();
-  if (opts.unit4_) tes::run_U4();
-  if (opts.unit5_) tes::run_U5();
-  if (opts.unit6_) tes::run_U6();
-  if (opts.unit7_) tes::run_U7();
+  if (opts.units_[1]) tes::run_U1();
+  if (opts.units_[2]) tes::run_U2();
+  if (opts.units_[3]) tes::run_U3();
+  if (opts.units_[4]) tes::run_U4();
+  if (opts.units_[5]) tes::run_U5();
+  if (opts.units_[6]) tes::run_U6();
+  if (opts.units_[7]) tes::run_U7();
 #endif
 }
 
+static bool deal_shell(const rsOpts& opts) {
+  return true;
+}
+
 }  // NS pln
 
 int main(int argc, char** argv) {
@@ -503,13 +507,14 @@ int main(int argc, char** argv) {
   if (opts.trace_specified())
     set_ltrace(opts.trace_);
 
-  if (opts.trace_ >= 8 or ltrace() >= 9 or ::getenv("pln_trace_env")) {
+  uint16_t tr = ltrace();
+  if (opts.trace_ >= 8 or tr >= 9 or ::getenv("pln_trace_env")) {
     s_env.dump("\n----env----\n");
     lout() << "-----------" << endl;
   }
 
   if (opts.ver_or_help()) {
-    if (ltrace() >= 2) {
+    if (tr >= 2) {
       printf("\t %s\n", _pln_VERSION_STR);
       printf("\t compiled:    %s\n", s_env.compTimeCS());
     }
@@ -518,12 +523,12 @@ int main(int argc, char** argv) {
     std::quick_exit(0);
   }
 
-  if (ltrace() >= 2) {
+  if (tr >= 2) {
     lprintf("\t %s\n", _pln_VERSION_STR);
     lprintf("\t compiled:  %s\n", s_env.compTimeCS());
   }
-  if (ltrace() >= 4) {
-    lprintf("ltrace()= %u  cmd.argc= %i\n", ltrace(), argc);
+  if (tr >= 4) {
+    lprintf("ltrace= %u  cmd.argc= %i\n", tr, argc);
   }
 
   if (opts.unit_specified()) {
@@ -552,10 +557,10 @@ int main(int argc, char** argv) {
   if (opts.is_fun_cmd()) {
     ok = deal_cmd(opts);
     if (ok) {
-      if (ltrace() >= 2) lputs("deal_cmd() succeeded.");
+      if (tr >= 2) lputs("deal_cmd() succeeded.");
       status = 0;
     } else {
-      if (ltrace() >= 2) lputs("deal_cmd() failed.");
+      if (tr >= 2) lputs("deal_cmd() failed.");
     }
     goto ret;
   }
@@ -563,10 +568,10 @@ int main(int argc, char** argv) {
   if (opts.is_fun_pinc() or opts.is_arg0_pinc() or opts.is_implicit_pinc()) {
     ok = deal_pinc(opts, true);
     if (ok) {
-      if (ltrace() >= 2) lputs("deal_pinc() succeeded.");
+      if (tr >= 2) lputs("deal_pinc() succeeded.");
       status = 0;
     } else {
-      if (ltrace() >= 2) lputs("deal_pinc() failed.");
+      if (tr >= 2) lputs("deal_pinc() failed.");
     }
     goto ret;
   }
@@ -575,7 +580,7 @@ int main(int argc, char** argv) {
     lputs("======== PARTITION MODE specified ========");
     ok = validate_partition_opts(opts);
     if (!ok) {
-      if (ltrace() >= 4) lputs("validate_partition_opts() failed.");
+      if (tr >= 4) lputs("validate_partition_opts() failed.");
       status = 2;
       goto ret;
     }
@@ -584,10 +589,28 @@ int main(int argc, char** argv) {
   if (opts.is_fun_partition() or opts.is_fun_pack()) {
     ok = deal_vpr(opts, true);
     if (ok) {
-      if (ltrace() >= 2) lputs("deal_vpr() succeeded.");
+      if (tr >= 2) lputs("deal_vpr() succeeded.");
       status = 0;
     } else {
-      if (ltrace() >= 2) lputs("deal_vpr() failed.");
+      if (tr >= 2) lputs("deal_vpr() failed.");
+    }
+    goto ret;
+  }
+
+  if (opts.is_fun_shell()) {
+    lputs("======== SHELL MODE specified ========");
+    ok = true; // validate_shell_opts(opts);
+    if (!ok) {
+      if (tr >= 4) lputs("validate_shell_opts() failed.");
+      status = 2;
+      goto ret;
+    }
+    ok = deal_shell(opts);
+    if (ok) {
+      if (tr >= 2) lputs("deal_shell() succeeded.");
+      status = 0;
+    } else {
+      if (tr >= 2) lputs("deal_shell() failed.");
     }
     goto ret;
   }
@@ -595,14 +618,14 @@ int main(int argc, char** argv) {
   // default function is stars
   ok = deal_stars(opts, true);
   if (ok) {
-    if (ltrace() >= 2) lputs("deal_stars() succeeded.");
+    if (tr >= 2) lputs("deal_stars() succeeded.");
     status = 0;
   } else {
-    if (ltrace() >= 2) lputs("deal_stars() failed.");
+    if (tr >= 2) lputs("deal_stars() failed.");
   }
 
 ret:
-  if (ltrace() >= 4)
+  if (tr >= 4)
     lprintf("(planner main status) %i\n", status);
   pln::flush_out(true);
   return status;