diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
new file mode 100644
index 000000000..8b3225f96
--- /dev/null
+++ b/.github/workflows/test.yml
@@ -0,0 +1,51 @@
+name: run Lmod tests
+on: [push, pull_request]
+
+jobs:
+  Lmod_tests:
+      runs-on: ${{ matrix.os }}
+      strategy:
+        matrix:
+          os: [ubuntu-latest, macos-latest]
+          luaVersion: ["5.1", "5.2", "5.3", "5.4"]
+      steps:
+      - name: Checkout code
+        uses: actions/checkout@v2
+      - name: install dependencies MacOS
+        if: matrix.os == 'macos-latest'
+        run: brew install coreutils
+      - name: install dependencies Linux
+        if: matrix.os == 'ubuntu-latest'
+        run: sudo apt install tcsh tcl8.6 tcl8.6-dev tcl-dev uuid r-base r-base-dev cmake fish tclsh zsh
+      - name: set up lua
+        uses: leafo/gh-actions-lua@v8.0.0
+        with:
+          luaVersion: ${{ matrix.luaVersion }}
+      - name: install luarocks
+        uses: leafo/gh-actions-luarocks@v4.0.0
+      - name: install lua dependencies
+        run: |
+          luarocks install luaposix
+          luarocks install luafileSystem
+          luarocks install luajson
+          luarocks install lua-term
+      - name: set up Hermes
+        run: |
+         cd /tmp
+         git clone https://github.com/rtmclay/Hermes.git
+         echo "$PWD/Hermes/bin" >> $GITHUB_PATH
+         cd -
+      - name: Run tests
+        run: tm
+      - name: show output of failed tests
+        if: ${{ failure() }}
+        run: |
+         # diff stdout/stderr for all tests in case of failure
+         for dir in $(ls -pd rt/* | grep '/$'); do
+           echo ">>>> ${dir}/err.txt"
+           diff -u ${dir}/t1/*/_err.left ${dir}/t1/*/_err.right || echo
+           echo ">>>> ${dir}/out.txt"
+           diff -u ${dir}/out.txt ${dir}/t1/*/out.txt || echo
+         done
+         echo ">>>> end2end output"
+         cat rt/end2end/t1/*/t1.log
diff --git a/Makefile.in b/Makefile.in
index eb0193248..2124872e4 100644
--- a/Makefile.in
+++ b/Makefile.in
@@ -185,6 +185,8 @@ ifneq ($(HAVE_LUAFILESYSTEM),yes)
   PKG_LFS := lfs
 endif
 FAST_TCL_INTERP           := @FAST_TCL_INTERP@
+TCL_INCLUDE     	  := @TCL_INCLUDE@
+TCL_LIBS	          := @TCL_LIBS@
 ifeq ($(FAST_TCL_INTERP),yes)
   PKGS    := $(PKGS) tcl2lua
   PKG_T2L := tcl2lua
@@ -344,6 +346,7 @@ src/computeHashSum: $(ComputeHashSum)
 tcl2lua:
 	if [ -d $(srcdir)/pkgs/tcl2lua ]; then                             \
            $(MAKE) -C $(srcdir)/pkgs/tcl2lua  LUA_INC=$(LUA_INCLUDE)       \
+	        TCL_INCLUDE=$(TCL_INCLUDE) TCL_LIBS=$(TCL_LIBS)            \
                 LIB=$(DESTDIR)$(LIB) LIBS=@LIBS@ CC=$(CC)                  \
                 SHARE=$(DESTDIR)$(LIBEXEC)                                 \
                 install;                                                   \
diff --git a/configure b/configure
index d3c56cacb..527802d32 100755
--- a/configure
+++ b/configure
@@ -624,7 +624,6 @@ ac_subst_vars='LTLIBOBJS
 LIBOBJS
 ZSH
 ZSH_SITE_FUNCTIONS_DIRS
-pkgConfig
 HAVE_LUA_TERM
 HAVE_LUAFILESYSTEM
 SYS_LUA_CPATH
@@ -643,9 +642,12 @@ BASENAME
 PATH_TO_SRC
 SYS_LD_PRELOAD
 SYS_LD_LIB_PATH
+TCL_LIBS
+TCL_INCLUDE
 EGREP
 GREP
 CPP
+pkgConfig
 LUA_SUFFIX
 PATH_TO_LUAC
 PATH_TO_LUA
@@ -714,6 +716,7 @@ infodir
 docdir
 oldincludedir
 includedir
+runstatedir
 localstatedir
 sharedstatedir
 sysconfdir
@@ -826,6 +829,7 @@ datadir='${datarootdir}'
 sysconfdir='${prefix}/etc'
 sharedstatedir='${prefix}/com'
 localstatedir='${prefix}/var'
+runstatedir='${localstatedir}/run'
 includedir='${prefix}/include'
 oldincludedir='/usr/include'
 docdir='${datarootdir}/doc/${PACKAGE}'
@@ -1078,6 +1082,15 @@ do
   | -silent | --silent | --silen | --sile | --sil)
     silent=yes ;;
 
+  -runstatedir | --runstatedir | --runstatedi | --runstated \
+  | --runstate | --runstat | --runsta | --runst | --runs \
+  | --run | --ru | --r)
+    ac_prev=runstatedir ;;
+  -runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
+  | --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
+  | --run=* | --ru=* | --r=*)
+    runstatedir=$ac_optarg ;;
+
   -sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
     ac_prev=sbindir ;;
   -sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
@@ -1215,7 +1228,7 @@ fi
 for ac_var in	exec_prefix prefix bindir sbindir libexecdir datarootdir \
 		datadir sysconfdir sharedstatedir localstatedir includedir \
 		oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
-		libdir localedir mandir
+		libdir localedir mandir runstatedir
 do
   eval ac_val=\$$ac_var
   # Remove trailing slashes.
@@ -1368,6 +1381,7 @@ Fine tuning of the installation directories:
   --sysconfdir=DIR        read-only single-machine data [PREFIX/etc]
   --sharedstatedir=DIR    modifiable architecture-independent data [PREFIX/com]
   --localstatedir=DIR     modifiable single-machine data [PREFIX/var]
+  --runstatedir=DIR       modifiable per-process data [LOCALSTATEDIR/run]
   --libdir=DIR            object code libraries [EPREFIX/lib]
   --includedir=DIR        C header files [PREFIX/include]
   --oldincludedir=DIR     C header files for non-gcc [/usr/include]
@@ -4014,14 +4028,75 @@ if test "$ALLOW_TCL_MFILES" = no ; then
 fi
 
 if test "$FAST_TCL_INTERP" = yes ; then
+   TCL_LIBS="-ltcl"
    OS=$(uname -s)
-   DIR=/usr/include/tcl
    if test "$OS" = Darwin ; then
-     DIR=$(xcrun --show-sdk-path)
-     DIR=${DIR}/usr/include
+     TCL_INCLUDE=$(xcrun --show-sdk-path)
+     TCL_INCLUDE=${DIR}/usr/include
+   else
+     for i in "" tcl tcl8.8 tcl8.7 tcl8.6 tcl8.5; do
+        if test -f /usr/include/$i/tcl.h ; then
+	   TCL_INCLUDE=/usr/include/$i
+	   break;
+	fi
+     done
+   fi
+
+   if test -z "$TCL_INCLUDE" ; then
+       # Extract the first word of "pkg-config", so it can be a program name with args.
+set dummy pkg-config; ac_word=$2
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for $ac_word" >&5
+$as_echo_n "checking for $ac_word... " >&6; }
+if ${ac_cv_path_pkgConfig+:} false; then :
+  $as_echo_n "(cached) " >&6
+else
+  case $pkgConfig in
+  [\\/]* | ?:[\\/]*)
+  ac_cv_path_pkgConfig="$pkgConfig" # Let the user override the test with a path.
+  ;;
+  *)
+  as_save_IFS=$IFS; IFS=$PATH_SEPARATOR
+for as_dir in $PATH
+do
+  IFS=$as_save_IFS
+  test -z "$as_dir" && as_dir=.
+    for ac_exec_ext in '' $ac_executable_extensions; do
+  if as_fn_executable_p "$as_dir/$ac_word$ac_exec_ext"; then
+    ac_cv_path_pkgConfig="$as_dir/$ac_word$ac_exec_ext"
+    $as_echo "$as_me:${as_lineno-$LINENO}: found $as_dir/$ac_word$ac_exec_ext" >&5
+    break 2
+  fi
+done
+  done
+IFS=$as_save_IFS
+
+  test -z "$ac_cv_path_pkgConfig" && ac_cv_path_pkgConfig=""""
+  ;;
+esac
+fi
+pkgConfig=$ac_cv_path_pkgConfig
+if test -n "$pkgConfig"; then
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: $pkgConfig" >&5
+$as_echo "$pkgConfig" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+
+
+       if  ! test x$pkgConfig = "x"; then
+           for i in tcl tcl8.8 tcl8.7 tcl8.6 tcl8.5; do
+               $pkgConfig --exists $i
+               if test $? = 0; then
+                   TCL_INCLUDE=`$pkgConfig --cflags $i | sed -e 's/^-I//' -e 's/ //g'`
+                   TCL_LIBS=`$pkgConfig --libs $i`
+                   break
+               fi
+           done
+       fi
    fi
 
-   CPPFLAGS="-I $DIR"
+   CPPFLAGS="-I $TCL_INCLUDE"
 
 
 ac_ext=c
@@ -4463,7 +4538,7 @@ for ac_lib in '' tcl tcl8.8 tcl8.7 tcl8.6 tcl8.5; do
     ac_res="none required"
   else
     ac_res=-l$ac_lib
-    LIBS="-l$ac_lib  $ac_func_search_save_LIBS"
+    LIBS="-l$ac_lib $TCL_LIBS $ac_func_search_save_LIBS"
   fi
   if ac_fn_c_try_link "$LINENO"; then :
   ac_cv_search_Tcl_CreateInterp=$ac_res
@@ -4492,6 +4567,11 @@ else
   rm -f makefile; as_fn_error $? "Unable to build Lmod with -ltcl Please install the tcl devel package or configure --with-fastTCLInterp=no to not require the tcl library" "$LINENO" 5
 fi
 
+
+   TCL_INCLUDE="$TCL_INCLUDE"
+
+   TCL_LIBS="$TCL_LIBS"
+
 fi
 
 
@@ -5040,7 +5120,6 @@ fi
 
   PATH_TO_LUA=$(FOLLOW_READLINK $FIND_PATH_TO_LUA)
 fi
-echo "2) PATH_TO_LUA: $PATH_TO_LUA"
 
 if ! command -v $PATH_TO_LUAC &>/dev/null ; then
   echo 'The program "'$PATH_TO_LUAC'" must be in your path'
diff --git a/configure.ac b/configure.ac
index 7714e891b..3fa5fd8b6 100644
--- a/configure.ac
+++ b/configure.ac
@@ -615,14 +615,35 @@ if test "$ALLOW_TCL_MFILES" = no ; then
 fi
 
 if test "$FAST_TCL_INTERP" = yes ; then
+   TCL_LIBS="-ltcl"
    OS=$(uname -s)
-   DIR=/usr/include/tcl
    if test "$OS" = Darwin ; then
-     DIR=$(xcrun --show-sdk-path)
-     DIR=${DIR}/usr/include
+     TCL_INCLUDE=$(xcrun --show-sdk-path)
+     TCL_INCLUDE=${DIR}/usr/include
+   else
+     for i in "" tcl tcl8.8 tcl8.7 tcl8.6 tcl8.5; do
+        if test -f /usr/include/$i/tcl.h ; then
+	   TCL_INCLUDE=/usr/include/$i
+	   break;
+	fi
+     done
+   fi
+	   
+   if test -z "$TCL_INCLUDE" ; then
+       AC_PATH_PROG(pkgConfig, pkg-config, "")
+       if  ! test x$pkgConfig = "x"; then
+           for i in tcl tcl8.8 tcl8.7 tcl8.6 tcl8.5; do
+               $pkgConfig --exists $i
+               if test $? = 0; then
+                   TCL_INCLUDE=`$pkgConfig --cflags $i | sed -e 's/^-I//' -e 's/ //g'`
+                   TCL_LIBS=`$pkgConfig --libs $i`
+                   break
+               fi
+           done
+       fi  
    fi
 
-   CPPFLAGS="-I $DIR"
+   CPPFLAGS="-I $TCL_INCLUDE"
 
    AC_CHECK_HEADER(tcl.h,
                    [AC_DEFINE([HAVE_TCL_H], 1, [Define to 1 if you have tcl.h])],[]) 
@@ -632,7 +653,10 @@ if test "$FAST_TCL_INTERP" = yes ; then
       AC_MSG_ERROR([Unable to build Lmod without tcl.h.  Please install the tcl devel package or configure --with-fastTCLInterp=no to not require tcl.h])
    fi
    AC_SEARCH_LIBS(Tcl_CreateInterp,[tcl] [tcl8.8] [tcl8.7] [tcl8.6] [tcl8.5],[],
-                [rm -f makefile; AC_MSG_ERROR([Unable to build Lmod with -ltcl Please install the tcl devel package or configure --with-fastTCLInterp=no to not require the tcl library])])
+                [rm -f makefile; AC_MSG_ERROR([Unable to build Lmod with -ltcl Please install the tcl devel package or configure --with-fastTCLInterp=no to not require the tcl library])], [$TCL_LIBS])
+
+   AC_SUBST(TCL_INCLUDE, "$TCL_INCLUDE")
+   AC_SUBST(TCL_LIBS, "$TCL_LIBS")
 fi
 
 AC_SUBST(SYS_LD_LIB_PATH)
@@ -752,7 +776,6 @@ if test ${PATH_TO_LUA:0:1} != '/' ; then
   AC_PATH_PROG(FIND_PATH_TO_LUA, $PATH_TO_LUA)
   PATH_TO_LUA=$(FOLLOW_READLINK $FIND_PATH_TO_LUA)
 fi
-echo "2) PATH_TO_LUA: $PATH_TO_LUA"
 
 if ! command -v $PATH_TO_LUAC &>/dev/null ; then
   echo 'The program "'$PATH_TO_LUAC'" must be in your path'
diff --git a/embed/Makefile b/embed/Makefile
index 6cd495246..cc12ebb7c 100644
--- a/embed/Makefile
+++ b/embed/Makefile
@@ -6,7 +6,7 @@ OBJ      := $(patsubst %.c, %.o, $(SRC))
 LUAINC   := /opt/apps/lua/lua/include
 OS       := $(shell uname -s)
 
-override CFLAGS   := $(CFLAGS) -DLUA_COMPAT_MODULE -fPIC -I $(LUAINC) -I /usr/include/tcl
+override CFLAGS   := $(CFLAGS) -DLUA_COMPAT_MODULE -fPIC -I $(LUAINC) -I $(TCL_INCLUDE)
 
 ifeq ($(OS),Darwin)
   LIB_OPTION= -bundle -undefined dynamic_lookup #for MacOS X
@@ -23,7 +23,7 @@ $(SONAME):
 	ln -s $(SONAMEV) $@
 
 $(LIBRARY): $(OBJ)
-	$(CC) $(CFLAGS) $(LIB_OPTION) -o $(LIBRARY) $(OBJ) -lc -ltcl
+	$(CC) $(CFLAGS) $(LIB_OPTION) -o $(LIBRARY) $(OBJ) -lc $(TCL_LIBS)
 
 install: all
 	cp $(LIBRARY) $(LUA_LIB)
diff --git a/pkgs/tcl2lua/Makefile b/pkgs/tcl2lua/Makefile
index 91970a6a0..cb84b1d9c 100644
--- a/pkgs/tcl2lua/Makefile
+++ b/pkgs/tcl2lua/Makefile
@@ -11,7 +11,7 @@ ifeq ($(OS),Darwin)
   DIR        := $(DIR)/usr/include
   LIB_OPTION := -bundle -undefined dynamic_lookup #for MacOS X
 else
-  DIR        := /usr/include/tcl
+  DIR        := $(TCL_INCLUDE)
   LIB_OPTION := -shared -Wl,-soname,$(SONAMEV) #for Linux
 endif
 override CFLAGS   := $(CFLAGS) -DLUA_COMPAT_MODULE -fPIC $(LUA_INC) -I $(DIR)
@@ -25,7 +25,7 @@ $(SONAME):
 	ln -s $(SONAMEV) $@
 
 $(LIBRARY): $(OBJ)
-	$(CC) $(CFLAGS) $(LIB_OPTION) -o $(LIBRARY) $(OBJ) $(LDFLAGS) -lc $(LIBS)
+	$(CC) $(CFLAGS) $(LIB_OPTION) -o $(LIBRARY) $(OBJ) $(LDFLAGS) -lc $(LIBS) $(TCL_LIBS)
 
 install: all
 	cp -a *.so* $(LIB)