diff --git a/Makefile b/Makefile
index 7ef8403..f91673c 100644
--- a/Makefile
+++ b/Makefile
@@ -1,6 +1,6 @@
 
 
-#  version  20211020
+#  version  20211111
 
 
 bin       ?=  bin
@@ -11,6 +11,8 @@ unit      ?=  /tmp/lxroot-unit
 Wextra    ?=  -Wextra  -Wno-unused-parameter
 gpp_opts  ?=  -fmax-errors=2  -Wall  -Werror  $(Wextra)
 
+deps      ?=  Makefile  lxroot.cpp  help.cpp  str.cpp  unit.cpp  |  $(bin)
+
 
 help:
 	@  echo  "\
@@ -29,13 +31,23 @@ Usage:								\n\
   make  unit-clean      #  delete the unit test environment	\n\
   make  demo-clean      #  delete the demo environment		\n\
   make  demo3-clean     #  delete the demo3 environment		\n\
-  make  static-clean    #  delete the static build environment  "
+  make  static-clean    #  delete the static build environment  \n\
+								\n\
+  make  demo3-root      #  enter demo3 as (simulated) root	"
 
 
-$(bin)/lxroot:  Makefile  lxroot.cpp  help.cpp  str.cpp  $(bin)
+$(bin)/lxroot:  $(deps)  $(bin)/lxroot-unit
+	$(bin)/lxroot-unit
 	g++  -g   $(gpp_opts)  lxroot.cpp  -o $@
 
 
+#  Note:  Lxroot has two sets of unit tests.
+#    1)  unit.cpp compiles to bin/lxroot-unit and test various C++ functions.
+#    2)  aux/unit.sh tests the compiled bin/lxroot executable.
+$(bin)/lxroot-unit:  $(deps)
+	g++  -g   $(gpp_opts)  unit.cpp  -o $@
+
+
 $(bin)  $(unit)  $(demo)  $(demo)-chromium:
 	mkdir  -p  $@
 
@@ -44,7 +56,8 @@ build:  $(bin)/lxroot
 
 
 clean:
-	rm  -f  bin/lxroot  ;  true
+	rm  -f  $(bin)/lxroot       ;  true
+	rm  -f  $(bin)/lxroot-unit  ;  true
 
 
 unit:  $(bin)/lxroot  $(unit)
@@ -60,7 +73,17 @@ unit-clean:  clean
 	rm  -rf   /tmp/lxroot-unit
 
 
-demo:  $(bin)/lxroot  $(demo)
+demo-prepare:  $(bin)/lxroot
+	@  echo
+	@  echo  'demo-prepare'
+	mkdir  -p  $(demo)/bin
+	@  #  note  in certain situations, $(bin) may equal $(demo)
+	-  cp  $(bin)/lxroot  $(demo)/bin/lxroot
+	cp     aux/demo.sh    $(demo)/bin/demo.sh
+
+
+#  demo:  $(bin)/lxroot  $(demo)
+demo:  demo-prepare
 	cp  $(bin)/lxroot  $(demo)/lxroot
 	bash  aux/demo.sh  demo1  $(demo)
 
@@ -78,64 +101,14 @@ static:
 #  demo 3  -----------------------------------------------------------  demo 3
 
 
-demo3_iso=$(demo)/dist/archlinux-2021.06.01-x86_64.iso
-demo3_url=https://mirror.rackspace.com/archlinux/iso/2021.06.01/archlinux-2021.06.01-x86_64.iso
 
 
-demo3-iso-soft:
-	if  [ ! -f $(demo3_iso) ]  ;  then  \
-	  wget  --continue  -O  $(demo3_iso)  $(demo3_url)  ;  fi
+demo3:  demo-prepare
+	/bin/sh  aux/demo.sh  demo3  $(demo)
 
 
-demo3-base:  demo3-iso-soft  $(bin)/lxroot
-
-	@  echo
-	@  echo  'demo3  create userland1'
-	bash  aux/demo.sh  demo1_extract  $(demo)  $(demo)/demo3
-	cp  /etc/resolv.conf  $(demo)/demo3/etc/
-	mkdir  -p  $(demo)/demo3/dist
-	ln  -f  $(demo3_iso)  $(demo)/demo3/dist
-
-	@  echo
-	cp  aux/demo.sh  $(demo)/demo3/root/
-	$(bin)/lxroot  -nw  $(demo)/demo3  \
-	  --  /bin/ash  /root/demo.sh  demo3_u1_create_u2
-
-	@  echo
-	cp  aux/demo.sh  $(demo)/demo3/userland2/root/
-	$(bin)/lxroot  -nr  $(demo)/demo3/userland2  \
-	  --  /bin/bash  /root/demo.sh  demo3_u2_create_u3
-
-	@  echo
-	cp  aux/demo.sh  $(demo)/demo3/userland2/userland3/root/
-	$(bin)/lxroot  -nr  $(demo)/demo3/userland2/userland3  \
-	  --  /bin/bash  /root/demo.sh  demo3_u3_finish
-
-	@  echo
-	mkdir  -p  $(demo)/demo3/userland2/userland3/$(HOME)
-
-
-demo3:
-	make  demo3-base    #  This allows overrding of the demo3 recipe.
-	@  echo
-	@  echo
-	@  echo  "(  The Demo #3 guest userland has been created.       )"
-	@  echo  "(                                                     )"
-	@  echo  "(  Make will now launch an interactive shell in the   )"
-	@  echo  "(  Demo #3 guest userland.                            )"
-	@  echo  "(                                                     )"
-	@  echo  "(  Please run 'chromium' in this shell to attempt to  )"
-	@  echo  "(  run Chromium.                                      )"
-	@  echo  "(                                                     )"
-	@  echo  "(  Please press ENTER when you are ready to proceed.  )"
-	@  echo
-	@  echo
-	@  read  discard
-	$(bin)/lxroot  -nx  $(demo)/demo3/userland2/userland3
-
-
-demo3-root:  demo3-base
-	$(bin)/lxroot  -nrx  $(demo)/demo3/userland2/userland3
+demo3-root:  demo-prepare
+	/bin/sh  aux/demo.sh  demo3  $(demo)  root
 
 
 demo3-clean:
@@ -143,5 +116,3 @@ demo3-clean:
 	mkdir  -p       /tmp/lxroot-demo/demo3
 	chmod  -R  u+w  /tmp/lxroot-demo/demo3
 	rm     -rf      /tmp/lxroot-demo/demo3
-
-
diff --git a/aux/demo.sh b/aux/demo.sh
index d6bec43..26e71c1 100644
--- a/aux/demo.sh
+++ b/aux/demo.sh
@@ -1,7 +1,7 @@
-#! /bin/bash
+#! /bin/sh
 
 
-#  version  20210610
+#  version  20211111
 
 
 set  -o errexit
@@ -9,19 +9,46 @@ set  -o errexit
 
 usage  ()  {    #  ----------------------------------------------------  usage
   echo
-  echo  'usage:'
-  echo  '  bash  demo.sh  demo1  <path>'
-  echo  '  bash  demo.sh  demo3  <path>'
-  echo  '  bash  demo.sh  alpine_extract  <path>  <subdir>'
+  echo  'usage:  bash  demo.sh  [options]'
+  echo
+  echo  'options:'
+  echo  '  demo1  <path>                #  run demo1 in <path>'
+  echo  '  demo3  <path>                #  run demo3 in <path> '
+  echo  '  demo3  <path>  root          #  enter the demo3 environment as root'
   return  ;  }
 
 
+main  ()  {    #  ------------------------------------------------------  main
+  case  "$1"  in
+    (demo1)            "$@"  ;;
+    (demo1_extract)    "$@"  ;;
+    (demo3)            "$@"  ;;
+    (demo3_u1)         "$@"  ;;
+    (demo3_u2)         "$@"  ;;
+    (demo3_u3)         "$@"  ;;
+    (*)                usage  ;  exit  1   ;;  esac
+  exit  ;  }
+
+
 #  These values are used by demo1 and demo1_extract.
-url='https://dl-cdn.alpinelinux.org/alpine/v3.13/releases/x86_64'
-file='alpine-minirootfs-3.13.5-x86_64.tar.gz'
+demo1_tgz='alpine-minirootfs-3.13.5-x86_64.tar.gz'
+demo1_url='https://dl-cdn.alpinelinux.org/alpine/v3.13/releases/x86_64'
 sha256='a103f4f5560d3ae59d53fcc44fe78a42e32e421c0a2981c03c297f23a3965071'
 
 
+#  These values are used by demo3.
+demo3_ver='2021.11.01'
+demo3_iso=archlinux-"$demo3_ver"-x86_64.iso
+demo3_url=https://mirror.rackspace.com/archlinux/iso/"$demo3_ver"
+demo3_md5='e42e562dd005fbe15ade787fe1ddba48'
+demo3_sha1='d81bff7f9b05653b048529d741edcce99bc97819'
+
+#  demo3 uses only a single Arch mirror in hopes of avoiding problems
+#  caused by skew across mirrors.  You may specify a different mirror
+#  below, if you wish.
+demo3_mirrorlist='Server = https://mirror.sfo12.us.leaseweb.net/archlinux/$repo/os/$arch'
+
+
 demo1_run  ()  {    #  --------------------------------------------  demo1_run
   local  demo="$1"
   echo
@@ -42,7 +69,7 @@ demo1_run  ()  {    #  --------------------------------------------  demo1_run
     demo1_verify
     echo
     trace  mkdir  demo1
-    trace  tar  xzf dist/"$file"  -C demo1  ;  fi
+    trace  tar  xzf dist/"$demo1_tgz"  -C demo1  ;  fi
 
   if  [ ! -f demo1/etc/resolv.conf ]  ;  then
     trace  cp  /etc/resolv.conf  demo1/etc/  ;  fi
@@ -77,6 +104,26 @@ mute  ()  {  >/dev/null  2>/dev/null  "$@"  ;  }    #  -----------------  mute
 trace  ()  {   echo  "+  $@"  ;  "$@"  ;  }    #  ---------------------  trace
 
 
+fetch  ()  {    #  ----------------------------------------------------  fetch
+
+  local  url="$1"  path="$2"
+
+  [ -f "$path" ]  &&  {  echo  "fetch  found  '$path'"  ;  return  ;  }
+
+  echo
+  echo  "fetch  $url"
+  echo
+
+  trace  wget  --no-clobber  -O "$path"  "$url"  &&  return
+
+  echo
+  echo  'fetch  fetch appears to have failed'
+  echo  "  url   $url"
+  echo  "  path  $(  realpath  "$path"  )"
+  echo
+  die  'demo.sh  fetch  die'  ;  }
+
+
 verify  ()  {    #  --------------------------------------------------  verify
 
   #  usage:  verify  [-v]  path  algo  expect
@@ -86,11 +133,13 @@ verify  ()  {    #  --------------------------------------------------  verify
   local  path="$1"  algo="$2"  expect="$3"
 
   if  [ "$verbose" = '1' ]  ;  then  echo  "$algo  $path"  ;  fi
-  local  actual=`  "$algo"  "$path"  `
+  local  actual="$(  "$algo"  "$path"  )"
   actual="${actual%% *}"
 
   if  [ ! "$actual" = "$expect" ]  ||  [ "$verbose" = '1' ]  ;  then
     echo  "verify    $algo  $path"
+    echo  "  path    $(  realpath  "$path"  )"
+    echo  "  size    $(  stat  --format '%s'  "$path"  )"
     echo  "  expect  $expect"
     echo  "  actual  $actual"
     fi
@@ -102,7 +151,7 @@ verify  ()  {    #  --------------------------------------------------  verify
 
 demo1_verify  ()  {    #  --------------------------------------  demo1_verify
 
-  local  path=dist/"$file"
+  local  path=dist/"$demo1_tgz"
   mkdir  -p  dist
   if  [ -e "$path" ]  ;  then
     echo
@@ -110,19 +159,22 @@ demo1_verify  ()  {    #  --------------------------------------  demo1_verify
   else
     echo
     echo  '#  ( Alpine Linux minirootfs - downloading file ...   )'
-    wget  --quiet  --no-clobber  -O "$path"  "$url"/"$file"  ;  fi
+    wget  --no-clobber  -O "$path"  "$demo1_url"/"$demo1_tgz"  ;  fi
 
   verify  "$path"  sha256sum  "$sha256"
   echo  "#  ( Alpine Linux minirootfs - file checksum is valid )"  ;  }
 
 
 demo1_extract  ()  {    #  ------------------------------------  demo1_extract
+
   local  demo="$1"  extract="$2"
+  local  url="$demo1_url"
+
   if  [ -d "$extract" ]  ;  then
-    echo  'demo1_extract  already done'  ;  return  ;  fi
+    echo  "demo1_extract  found  '$extract'"  ;  return  ;  fi
   mkdir  -p  "$demo"  ;  cd  "$demo"  ;  demo1_verify
   mkdir  -p  "$extract"
-  trace  tar  xzf dist/"$file"  -C "$extract"  ;  }
+  trace  tar  xzf dist/"$demo1_tgz"  -C "$extract"  ;  }
 
 
 demo1 ()  {    #  -----------------------------------------------------  demo1
@@ -135,32 +187,43 @@ demo1 ()  {    #  -----------------------------------------------------  demo1
 #  demo 3  -----------------------------------------------------------  demo 3
 
 
-#  demo3 uses only a single mirror in hopes of avoiding problems
-#  caused by mirror skew.  You may specify a different mirror below,
-#  if you wish.
+demo3_verify  ()  {    #  --------------------------------------  demo3_verify
+  [ -f dist/"$iso" ]  ||  fetch  "$url"/"$iso"  dist/"$iso"
+  verify  -v  dist/"$iso"  md5sum     "$demo3_md5"
+  verify  -v  dist/"$iso"  sha1sum    "$demo3_sha1"
+  return  ;  }
 
-demo3_mirrorlist='Server = https://mirror.sfo12.us.leaseweb.net/archlinux/$repo/os/$arch'
 
+demo3_host  ()  {    #  ------------------------------------------  demo3_host
 
-demo3_u1_create_u2  ()  {    #  --------------------------  demo3_u1_create_u2
+  #  demo3_host is run on the host.
+  #  demo3_host creates userland #1 (Alpine).
 
-  if  [ -d /userland2 ]  ;  then
-    echo  'demo3_u1_create_u2  already done'  ;  return  ;  fi
+  echo
+  echo  "demo3  $*"
+
+  trace  cd  "$demo"
+  demo1_extract  .  demo3
+  demo3_verify
 
-  echo  'demo3_u1_create_u2'
+  trace  mkdir  -p  demo3/dist/
+  trace  cp  /etc/resolv.conf  demo3/etc/
+  trace  cp  bin/demo.sh       demo3/dist/
+  trace  ln  -f  dist/"$iso"   demo3/dist/"$iso"
+
+  return  ;  }
+
+
+demo3_u1_extract  ()  {    #  ------------------------------  demo3_u1_extract
+
+  [ -d /userland2 ]  &&  {
+    echo  'demo3_u1_extract  found  /userland2'  ;  return  ;  }
 
   if  [ ! -f /root/update ]  ;  then
     trace  apk  update  ;  touch  /root/update  ;  fi
 
   trace  apk  add  p7zip  squashfs-tools
 
-  local  iso='archlinux-2021.06.01-x86_64.iso'
-
-  verify  -v  /dist/"$iso"  md5sum     1bf76d864651cc6454ab273fd3d2226a
-  verify  -v  /dist/"$iso"  sha1sum    6c41a22fb3c5eabfb7872970a9b5653ec47c3ad5
-  verify  -v  /dist/"$iso"  sha256sum  \
-    bd23f81dfb7a224589ccabed7f690c33fbc243bae3f32d295547a64445ae0245
-
   trace  mkdir  -p  /iso-extract
   trace  cd  /iso-extract
   trace  mute  7z  x  -aos  /dist/"$iso"  arch/x86_64/airootfs.sfs
@@ -171,7 +234,9 @@ demo3_u1_create_u2  ()  {    #  --------------------------  demo3_u1_create_u2
   trace  sha512sum  -c airootfs.sha512
 
   trace  cd  /iso-extract
-  trace  unsquashfs  -no-xattrs  /iso-extract/arch/x86_64/airootfs.sfs
+  [ -d squashfs-root ]  \
+    ||  trace  unsquashfs  -no-xattrs  /iso-extract/arch/x86_64/airootfs.sfs  \
+    ||  true
   trace  mv  squashfs-root  userland2
   trace  rm  -f  userland2/etc/resolv.conf
   trace  cp  /etc/resolv.conf  userland2/etc/resolv.conf
@@ -190,12 +255,28 @@ demo3_u1_create_u2  ()  {    #  --------------------------  demo3_u1_create_u2
   return  ;  }
 
 
-demo3_u2_create_u3  ()  {    #  --------------------------  demo3_u2_create_u3
+demo3_u1  ()  {    #  ----------------------------------------------  demo3_u1
+
+  #  demo3_u1 is run in userland #1 (Alpine).
+  #  demo3_u1 creates userland #2 (Arch bootstrap).
+
+  local  iso="$demo3_iso"
+
+  echo
+  echo  'demo3_u1'
+
+  demo3_u1_extract
+
+  trace  mkdir  -p  /userland2/dist/
+  trace  cp  /dist/demo.sh  /userland2/dist/
+
+  return  ;  }
+
 
-  if  [ -d /userland3 ]  ;  then
-    echo  'demo3_u2_create_u3  already done'  ;  return  ;  fi
+demo3_u2_bootstrap  ()  {    #  --------------------------  demo3_u2_bootstrap
 
-  echo  'demo3_u2_create_u3'
+  [ -d /userland3 ]  &&  {
+    echo  "demo3_u2_bootstrap  found  /userland3"  ;  return  ;  }
 
   trace  pacman-key  --init
   trace  pacman-key  --populate  archlinux
@@ -215,13 +296,31 @@ demo3_u2_create_u3  ()  {    #  --------------------------  demo3_u2_create_u3
   return  ;  }
 
 
-demo3_u3_finish  ()  {    #    #  ---------------------------  demo3_u3_finish
+demo3_u2  ()  {    #  ----------------------------------------------  demo3_u2
+
+  #  demo3_u2 is run in userland #2 (Arch bootstrap).
+  #  demo3_u2 creates userland #$3 (Arch actual).
+
+  echo
+  echo  'demo3_u2'
+
+  demo3_u2_bootstrap
+
+  trace  mkdir  -p  /userland3/dist/
+  trace  cp  /dist/demo.sh  /userland3/dist/
+
+  return  ;  }
+
+
+demo3_u3  ()  {    #  ----------------------------------------------  demo3_u3
 
-  if  [ -f /usr/bin/chromium ]  ;  then
-    echo  'demo3_u3_finish  already done'  ;  return  ;  fi
+  #  demo3_3 is run in userland #3 (Arch actual).
 
   echo
-  echo  'demo3_u3_finish'
+  echo  'demo3_u3'
+
+  [ -f /usr/bin/chromium ]  &&  {
+    echo  'demo3_u3  found  /usr/bin/chromium'  ;  return  ;  }
 
   trace  mkdir  -p  /tmp/.X11-unix
   trace  pacman  -Sy  --noconfirm  chromium
@@ -229,15 +328,62 @@ demo3_u3_finish  ()  {    #    #  ---------------------------  demo3_u3_finish
   return  ;  }
 
 
-main  ()  {    #  ------------------------------------------------------  main
-  case  "$1"  in
-    (demo1)               "$1"  "$2"        ;;
-    (demo1_extract)       "$1"  "$2"  "$3"  ;;
-    (demo3_u1_create_u2)  "$1"              ;;    #  run in userland1
-    (demo3_u2_create_u3)  "$1"              ;;    #  run in userland2
-    (demo3_u3_finish)     "$1"              ;;    #  run in userland3
-    (*)                 usage  ;  exit  1   ;;  esac
-  exit  ;  }
+demo3_u3_shell  ()  {    #  ----------------------------------  demo3_u3_shell
+
+  mkdir  -p  demo3/userland2/userland3/home/"$USER"  ||  true
+
+  echo
+  echo
+  echo  "(  The Demo #3 guest userland has been created.       )"
+  echo  "(                                                     )"
+  echo  "(  Make will now launch an interactive shell in the   )"
+  echo  "(  Demo #3 guest userland.                            )"
+  echo  "(                                                     )"
+  echo  "(  Please run 'chromium' in this shell to attempt to  )"
+  echo  "(  run Chromium.                                      )"
+  echo  "(                                                     )"
+  echo  "(  Please press ENTER when you are ready to proceed.  )"
+
+  read  discard
+  bin/lxroot  -nx  demo3/userland2/userland3
+
+  return  ;  }
+
+
+demo3_u3_shell_root  ()  {    #  ------------------------  demo3_u3_shell_root
+  trace  cd  "$demo"
+  trace  bin/lxroot  -nr  demo3/userland2/userland3  ;  }
+
+
+demo3  ()  {    #  ----------------------------------------------------  demo3
+
+  local  demo="$1"  mode="$2"
+  local  iso="$demo3_iso"
+  local  url="$demo3_url"
+
+  if  [ "$root" = 'root' ]  ;  then
+    echo
+    echo  'demo3  root'
+    return  ;  fi
+
+  local  u1='demo3'
+  local  u2='demo3/userland2'
+  local  u3='demo3/userland2/userland3'
+
+  demo3_host
+  trace  bin/lxroot  -nr  "$u1"  --  /bin/sh  /dist/demo.sh  demo3_u1
+  trace  bin/lxroot  -nr  "$u2"  --  /bin/sh  /dist/demo.sh  demo3_u2
+  trace  bin/lxroot  -nr  "$u3"  --  /bin/sh  /dist/demo.sh  demo3_u3
+
+  case  "$mode"  in
+    (''    )  demo3_u3_shell       ;;
+    ('root')  demo3_u3_shell_root  ;;
+    (*)       die  "demo3  bad mode  '$mode'"  ;;  esac
+
+  return  ;  }
+
+
+#  main  ---------------------------------------------------------------  main
 
 
 main  "$@"
diff --git a/changelog.txt b/changelog.txt
index 2c6c2e8..9e4d256 100644
--- a/changelog.txt
+++ b/changelog.txt
@@ -1,5 +1,22 @@
 
 
+20211115
+
+Git log:  Created unit.cpp.  Updated demo3(#7).  Fixed MS_ & ST_ enum bug(#6).
+Retired 'master' branch.
+Created new 'main' branch.
+The above two chanegs were done for copyright/authorship reasons.
+They removed a trivial patch from a third party.
+Rebuilt demo3.  Shifted parts of demo3 from Makefile to aux/demo.sh.
+The above demo3 changes fixed Issue #7.
+Fixed enum vs. #define MS_ vs ST_ bug.  (Fixing issue #6.)
+
+
+20211030
+
+Moved C++ unit tests to unit.cpp.
+
+
 20211028
 
 Ipmelmented proper fix of GitHub issue #3, via statfs().
diff --git a/lxroot.cpp b/lxroot.cpp
index 66eb8b8..38896a0 100644
--- a/lxroot.cpp
+++ b/lxroot.cpp
@@ -728,8 +728,9 @@ struct  Syscall  {    //  xxsy  -----------------------------  struct  Syscall
 
     //  the below verbose yet simple implementation should optimize well.
 
-    #define  if_equal(     a, b )  (   a == b                ? b : 0 )
-    #define  if_not_equal( a, b )  ( ( a != b ) && ( n & a ) ? b : 0 )
+    #define  c(a)  ( (flags_t) (a) )
+    #define  if_equal(     a, b )  (   c(a) == c(b)                ? b : 0 )
+    #define  if_not_equal( a, b )  ( ( c(a) != c(b) ) && ( n & a ) ? b : 0 )
 
     constexpr flags_t  copy_these_bits  =
       if_equal         (  ST_RDONLY,       MS_RDONLY       )
@@ -753,25 +754,13 @@ struct  Syscall  {    //  xxsy  -----------------------------  struct  Syscall
       |  if_not_equal  (  ST_NODIRATIME,   MS_NODIRATIME   )
       |  if_not_equal  (  ST_RELATIME,     MS_RELATIME     );
 
+    #undef  c
     #undef  if_equal
     #undef  if_not_equal
 
     return  ( n & copy_these_bits ) | shifted_bits;  }
 
 
-  static void  st_to_ms_unit_test  ()  {    //  ----------  st_to_ms_unit_test
-    assert (  st_to_ms ( ST_RDONLY      ) == MS_RDONLY       );
-    assert (  st_to_ms ( ST_NOSUID      ) == MS_NOSUID       );
-    assert (  st_to_ms ( ST_NODEV       ) == MS_NODEV        );
-    assert (  st_to_ms ( ST_NOEXEC      ) == MS_NOEXEC       );
-    assert (  st_to_ms ( ST_SYNCHRONOUS ) == MS_SYNCHRONOUS  );
-    assert (  st_to_ms ( ST_MANDLOCK    ) == MS_MANDLOCK     );
-    assert (  st_to_ms ( ST_NOATIME     ) == MS_NOATIME      );
-    assert (  st_to_ms ( ST_NODIRATIME  ) == MS_NODIRATIME   );
-    assert (  st_to_ms ( ST_RELATIME    ) == MS_RELATIME     );
-    return;  }
-
-
   void  umount2  ( Str target, int flags )  {   //  --------  Syscall  umount2
     try1( :: umount2, "  umount2  %s  0x%x", target.s, flags );  }
 
@@ -796,10 +785,6 @@ struct  Syscall  {    //  xxsy  -----------------------------  struct  Syscall
     die_pe ( "write  %d  %ld", fd, (long int) count );  }
 
 
-  static void  unit_test  ()  {    //  -------------------  Syscall  unit_test
-    st_to_ms_unit_test();  }
-
-
 };    //  end  struct  Syscall  ------------------------  end  struct  Syscall
 
 
@@ -811,6 +796,7 @@ Syscall  sys;    //  xxsy  --------------------------------------  global  sys
 struct  Option_Reader    //  xxop  --------------------  struct  Option_Reader
   :  private  Option  {
 
+
   const Option &  o;    //  const access to the Option base class
 
 
@@ -1230,6 +1216,7 @@ struct  Env_Tool  :  Lib  {  //  xxen  ---------------------  struct  Env_Tool
 
   static void  ps1  ()  {    //  ------------------------------  Env_Tool  ps1
     //  20200626  todo?  add custom prompts for other shells
+    //  20211030  probably not.  use selective env var passthru instead.
     if  (  st.command[0] == "/bin/bash"
 	   ||  is_busybox ( st.command[0] )  )  {  ps1_bash();  }  }
 
@@ -1496,18 +1483,12 @@ class  Lxroot  :  Lib  {    //  xxlx  -------------------------  class  Lxroot
 
 
 
-void  unit_test  ()  {    //  -------------------------------------  unit_test
-  mStr    :: unit_test();
-  oStr    :: unit_test();
-  Argv    :: unit_test();
-  Syscall :: unit_test();  }
-
-
+#ifndef  LXROOT_MAIN_SKIP
 int  main  ( const int argc, str argv[] )  {    //  --------------------  main
-  unit_test();
   if  ( argc < 2 )  {  Lib :: help_print();  }
   mut .argv  =  argv;
   return  Lxroot() .main();  }
+#endif
 
 
 
diff --git a/str.cpp b/str.cpp
index 3a36a04..6e08d56 100644
--- a/str.cpp
+++ b/str.cpp
@@ -4,7 +4,7 @@
 //  Copyright (c) 2021 Parke Bostrom, parke.nexus at gmail.com
 //  Distributed under GPLv3 (see end of file) WITHOUT ANY WARRANTY.
 
-//  version  20211019
+//  version  20211030
 
 
 
@@ -83,6 +83,7 @@ struct  mFrag  {    //  xxmf  ---------------------------------  struct  mFrag
 
 struct  mStr  {    //  xxms  -----------------------------------  struct  mStr
 
+
   //  mStr is a convenience wrapper around a mstr (i.e. 'const char *').
   //  s points to either (a) nullptr or (b) a null-terminated string.
   //  an mStr does not own s.  (But see also derived class oStr.)
@@ -148,9 +149,6 @@ struct  mStr  {    //  xxms  -----------------------------------  struct  mStr
       a  =  c;  }  }
 
 
-  static void  basename_test  ( Str s, Str expect );    //  ------------------
-
-
   Frag  capture_until  ( char c )  const  {    //  ------  mStr  capture_until
     mStr  p  =  s;  while  (  p && * p  &&  * p != c  )  {  p ++;  }
     return  Frag ( s, p.s - s );  }
@@ -235,28 +233,6 @@ struct  mStr  {    //  xxms  -----------------------------------  struct  mStr
     return  skip_all('/') .capture_until('/');  }
 
 
-  static void  unit_test  ()  {    //  ----------------------  mStr  unit_test
-
-    basename_test ( "",          ""    );
-    basename_test ( "/",         "/"   );
-    basename_test ( "//",        "/"   );
-    basename_test ( "///",       "/"   );
-    basename_test ( "a",         "a"   );
-    basename_test ( "/b",        "b"   );
-    basename_test ( "c/",        "c"   );
-    basename_test ( "/d/",       "d"   );
-    basename_test ( "e/f",       "f"   );
-    basename_test ( "/g/h",      "h"   );
-    basename_test ( "abc",       "abc" );
-    basename_test ( "/def",      "def" );
-    basename_test ( "ghi/",      "ghi" );
-    basename_test ( "/jkl/",     "jkl" );
-    basename_test ( "mno/pqr",   "pqr" );
-    basename_test ( "/stu/vwx",  "vwx" );
-    basename_test ( "./xyz",     "xyz" );
-
-    return;  }
-
 
 };    //  end  struct  mStr  ------------------------------  end  struct  mStr
 
@@ -293,7 +269,6 @@ Concat_2  s  ( Str a, Str b = 0, Str c = 0 )  {    //  xxs  -------  global  s
 
 
 
-
 struct  oStr  :  mStr   {    //  xxos  -------------------------  struct  oStr
 
 
@@ -339,9 +314,6 @@ struct  oStr  :  mStr   {    //  xxos  -------------------------  struct  oStr
     oStr  rv;    rv.s=s.s;    rv.n=s.n();    return rv;  }
 
 
-  static void  unit_test  ();    //  ------------------------  oStr  unit_test
-
-
 };    //  end  struct  oStr  ------------------------------  end  struct  oStr
 
 
@@ -390,32 +362,6 @@ Concat  operator +  ( str a, Str b )  {    //  ---------------------  ::  op +
   return  Frag(a) + b;  }
 
 
-void  mStr :: basename_test  ( Str s, Str expect )  {    //  --  basename_test
-    if  ( s.basename() == expect )  {  return;  }
-    oStr  actual  =  s.basename();
-    printe ( "basename_test  failed\n" );
-    printe ( "  s       %s\n", s.s      );
-    printe ( "  expect  %s\n", expect.s );
-    printe ( "  actual  %s\n", actual.s );
-    abort();  }
-
-
-void  oStr :: unit_test  ()  {    //  -----------------------  oStr  unit_test
-    Str   a   =  "a";
-    Str   b   =  "b";
-    oStr  ab  =  a + b;
-    assert  ( ab == "ab" );
-    assert  ( ab == a+b  );
-    Frag  c   =  "c";
-    Frag  d   =  "d";
-    oStr  cd  =  c + "=" + d;
-    assert  ( cd == "c=d" );
-    oStr  ef  =  cd + "ef" + "gh";
-    assert  ( ef == "c=defgh" );
-    assert  ( cd == "c=d" );
-    ;;;  }
-
-
 //  end  struct  Concat  --------------------------------  end  struct  Concat
 
 
@@ -488,29 +434,6 @@ struct  Argv  {    //  xxar  -----------------------------------  struct  Argv
       printe  ( "%s%s\n", s.s, o[0].s );  }  }
 
 
-  static void  unit_test  ()  {    //  ----------------------  Argv  unit_test
-
-    str  p[]  =  { "a=1", "b=2", "c=3", nullptr };
-    Argv  a(p);
-
-    assert ( a[0] == p[0] );
-    assert ( a[1] == p[1] );
-    assert ( a[2] == p[2] );
-    assert ( a[3] == p[3] );
-
-    assert ( a[0] == a.p[0] );
-    assert ( a[1] == a.p[1] );
-    assert ( a[2] == a.p[2] );
-    assert ( a[3] == a.p[3] );
-    assert ( a.concat() == "a=1  b=2  c=3" );
-
-    assert ( a.env_get("a") == p[0] );
-    assert ( a.env_get("b") == p[1] );
-    assert ( a.env_get("c") == p[2] );
-
-    ;;;  }
-
-
 };    //  end  struct  Argv  ------------------------------  end  struct  Argv
 
 
diff --git a/unit.cpp b/unit.cpp
new file mode 100644
index 0000000..6181e62
--- /dev/null
+++ b/unit.cpp
@@ -0,0 +1,143 @@
+
+
+//  unit.cpp  -  Lxroot's C++ unit tests.
+//  Copyright (c) 2021 Parke Bostrom, parke.nexus at gmail.com
+//  Distributed under GPLv3 (see end of file) WITHOUT ANY WARRANTY.
+
+//  version  20211030
+
+
+#define   LXROOT_MAIN_SKIP  1
+#include  "lxroot.cpp"
+
+
+struct  Unit  {    //  -----------------------------------------  struct  Unit
+
+
+  void  t_basename  ( Str s, Str expect )  {    //  --------  Unit  t_basename
+    if  ( s.basename() == expect )  {  return;  }
+    oStr  actual  =  s.basename();
+    printe ( "basename_test  failed\n" );
+    printe ( "  s       %s\n", s.s      );
+    printe ( "  expect  %s\n", expect.s );
+    printe ( "  actual  %s\n", actual.s );
+    abort();  }
+
+
+  void  t_basename_all  ()  {    //  -------------------  Unit  t_basename_all
+
+    t_basename ( "",          ""    );
+    t_basename ( "/",         "/"   );
+    t_basename ( "//",        "/"   );
+    t_basename ( "///",       "/"   );
+    t_basename ( "a",         "a"   );
+    t_basename ( "/b",        "b"   );
+    t_basename ( "c/",        "c"   );
+    t_basename ( "/d/",       "d"   );
+    t_basename ( "e/f",       "f"   );
+    t_basename ( "/g/h",      "h"   );
+    t_basename ( "abc",       "abc" );
+    t_basename ( "/def",      "def" );
+    t_basename ( "ghi/",      "ghi" );
+    t_basename ( "/jkl/",     "jkl" );
+    t_basename ( "mno/pqr",   "pqr" );
+    t_basename ( "/stu/vwx",  "vwx" );
+    t_basename ( "./xyz",     "xyz" );
+
+    return;  }
+
+
+  void  t_oStr  ()  {    //  -----------------------------------  Unit  t_oStr
+
+    Str   a   =  "a";
+    Str   b   =  "b";
+    oStr  ab  =  a + b;
+    assert  ( ab == "ab" );
+    assert  ( ab == a+b  );
+    Frag  c   =  "c";
+    Frag  d   =  "d";
+    oStr  cd  =  c + "=" + d;
+    assert  ( cd == "c=d" );
+    oStr  ef  =  cd + "ef" + "gh";
+    assert  ( ef == "c=defgh" );
+    assert  ( cd == "c=d" );
+
+    return;  }
+
+
+  static void  t_Argv  ()  {    //  ----------------------------  Unit  t_Argv
+
+    str  p[]  =  { "a=1", "b=2", "c=3", nullptr };
+    Argv  a(p);
+
+    assert ( a[0] == p[0] );
+    assert ( a[1] == p[1] );
+    assert ( a[2] == p[2] );
+    assert ( a[3] == p[3] );
+
+    assert ( a[0] == a.p[0] );
+    assert ( a[1] == a.p[1] );
+    assert ( a[2] == a.p[2] );
+    assert ( a[3] == a.p[3] );
+    assert ( a.concat() == "a=1  b=2  c=3" );
+
+    assert ( a.env_get("a") == p[0] );
+    assert ( a.env_get("b") == p[1] );
+    assert ( a.env_get("c") == p[2] );
+
+    return;  }
+
+
+  void  t_st_to_ms  ()  {    //  ---------------------------  Unit  t_st_to_ms
+
+    const auto  st_to_ms  =  Syscall :: st_to_ms;
+
+    assert(    st_to_ms ( ST_RDONLY      )  ==  MS_RDONLY         );
+    assert(    st_to_ms ( ST_NOSUID      )  ==  MS_NOSUID         );
+    assert(    st_to_ms ( ST_NODEV       )  ==  MS_NODEV          );
+    assert(    st_to_ms ( ST_NOEXEC      )  ==  MS_NOEXEC         );
+    assert(    st_to_ms ( ST_SYNCHRONOUS )  ==  MS_SYNCHRONOUS    );
+    assert(    st_to_ms ( ST_MANDLOCK    )  ==  MS_MANDLOCK       );
+    assert(    st_to_ms ( ST_NOATIME     )  ==  MS_NOATIME        );
+    assert(    st_to_ms ( ST_NODIRATIME  )  ==  MS_NODIRATIME     );
+    assert(    st_to_ms ( ST_RELATIME    )  ==  MS_RELATIME       );
+
+    return;  }
+
+
+  void  main  ()  {    //  -------------------------------------  Unit  main
+    t_basename_all();
+    t_oStr();
+    t_Argv();
+    t_st_to_ms();
+    printf ( "unit.cpp  done  all tests passed\n" );  }
+
+
+};    //  end  struct  Unit  ------------------------------  end  struct  Unit
+
+
+
+
+int  main  ()  {    //  --------------------------------------------  ::  main
+  Unit() .main();
+  return  0;  }
+
+
+
+
+//  unit.cpp  -  Lxroot's C++ unit tests.
+//
+//  Copyright (c) 2021 Parke Bostrom, parke.nexus at gmail.com
+//
+//  This program is free software: you can redistribute it and/or
+//  modify it under the terms of version 3 of the GNU General Public
+//  License as published by the Free Software Foundation.
+//
+//  This program is distributed in the hope that it will be useful,
+//  but WITHOUT ANY WARRANTY; without even the implied warranty of
+//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See version
+//  3 of the GNU General Public License for more details.
+//
+//  You should have received a copy of version 3 of the GNU General
+//  Public License along with this program.  If not, see
+//  <https://www.gnu.org/licenses/>.