diff --git a/filesystem.spec b/filesystem.spec
index 9bda07c..3b133d1 100644
--- a/filesystem.spec
+++ b/filesystem.spec
@@ -1,8 +1,8 @@
 %define tty_group 4
 
 Name:          filesystem
-Version:       2.2
-Release:       21mamba
+Version:       2.3
+Release:       4mamba
 Summary:       The basic directory layout for a Linux system
 Group:         System/Configuration
 Vendor:        openmamba
@@ -13,7 +13,6 @@ License:       Public Domain
 ## AUTOBUILDREQ-BEGIN
 ## AUTOBUILDREQ-END
 BuildArch:     noarch
-BuildRoot:     %{_tmppath}/%{name}-%{version}-build
 
 %description
 The filesystem package is one of the basic packages that is installed on an openmamba Linux system. 
@@ -25,8 +24,8 @@ Filesystem contains the basic directory layout for a Linux operating system, inc
 
 %install
 [ "%{buildroot}" != / ] && rm -rf %{buildroot}
-install -d %{buildroot}/{bin,boot,dev/pts,etc/opt,home,%_lib,mnt,proc}
-install -d %{buildroot}/{root,sbin,tmp,usr/local,var,opt,initrd}
+install -d %{buildroot}/{boot,dev/pts,etc/opt,home,%_lib,mnt,proc}
+install -d %{buildroot}/{root,tmp,usr/local,var,opt,initrd}
 
 for dirname in %{buildroot}/usr %{buildroot}/usr/local; do
    install -d $dirname/{bin,etc,include,%_lib,sbin,share,src}
@@ -51,6 +50,9 @@ install -d %{buildroot}/run
 install -d %{buildroot}/srv
 install -d %{buildroot}/sys
 
+# Owning /bin and /sbin symlinks 
+#ln -s usr/bin %{buildroot}/bin
+#ln -s usr/sbin %{buildroot}/sbin
 ln -s ../var/tmp %{buildroot}/usr
 ln -s ../mail %{buildroot}/var/spool/mail
 ln -s ../run %{buildroot}/var/run
@@ -65,12 +67,60 @@ ln -s ../run %{buildroot}/var/run
 
 %pre
 [ -L /var/run ] || {
+   # /var/run -> /run migration
    mv /var/run /var/run.rpmold
    for f in /var/run.rpmold/*; do
       b=`basename $f`
       [ -e /run/$b ] || mv $f /run/
    done
 }
+[ -L /bin -a -L /sbin ] || {
+  # /bin -> /usr/bin and /sbin -> /usr/sbin migration
+  for f in mv rm rmdir ln; do
+   [ -e /usr/bin/$f ] || cp /bin/$f /usr/bin/$f
+  done
+  for d in bin sbin; do
+   [ -L /$d ] && continue
+   echo "Migrating /$d to /usr/$d..."
+   for f in /$d/*; do
+      dest=/usr$f
+      if [ -e $dest ]; then
+         #echo "$f exists as $dest"
+         if [ -L $f ]; then
+            linkdest=`readlink $f`
+            #echo "$f is a symlink to $linkdest"
+            /usr/bin/rm -f $f
+         elif [ -L $dest ]; then
+            linkdest=`readlink $dest`
+            #echo "$dest is a symlink to $linkdest"
+            /usr/bin/rm -f $dest && mv $f $dest
+         else
+            #echo "$f exists as a file also as $linkdest"
+            /usr/bin/rm -f $f
+         fi
+      else
+         if [ -L $f ]; then
+            linkdest=`readlink $f`
+            if [ "${linkdest:0:3}" = "../" ]; then
+               fulllinkdest=`readlink -f $f`
+               #echo "$f is a symlink pointing to ../ -> fixing"
+               /usr/bin/ln -s $fulllinkdest $dest
+               /usr/bin/rm -f $f
+            else
+               /usr/bin/mv $f $dest
+            fi
+         else
+            /usr/bin/mv $f $dest
+         fi
+      fi
+   done
+   /usr/bin/rmdir /$d || /usr/bin/mv /$d /$d.notmigrated
+   /usr/bin/ln -s usr/$d /$d
+  done
+}
+# Add if missing for safety
+[ -e /bin ] || /usr/bin/ln -s usr/bin /bin
+[ -e /sbin ] || /usr/bin/ln -s usr/sbin /sbin
 :
 
 %post
@@ -80,10 +130,22 @@ if [ $1 -ge 1 ]; then
 fi
 :
 
+%triggerpostun -p /usr/bin/bash -- filesystem < 2.3
+# /bin and /sbin are removed during old filesystem postun
+[ -e /bin ] || /usr/bin/ln -s usr/bin /bin
+[ -e /sbin ] || /usr/bin/ln -s usr/sbin /sbin
+:
+
+%posttrans -p /usr/bin/bash
+# /bin and /sbin are removed on upgrade
+[ -e /bin ] || /usr/bin/ln -s usr/bin /bin
+[ -e /sbin ] || /usr/bin/ln -s usr/sbin /sbin
+:
+
 %files
 %defattr(-,root,root)
 %attr(0755,root,root) %dir /
-%dir /bin
+#/bin
 %dir /boot
 %dir /dev
 %dir /dev/pts
@@ -96,7 +158,7 @@ fi
 %dir /proc
 %attr(0750,root,root) %dir /root
 %dir /run
-%dir /sbin
+#/sbin
 %dir /srv
 %dir /sys
 %attr(1777,root,root) %dir /tmp
@@ -169,6 +231,20 @@ fi
 /usr/tmp
 
 %changelog
+* Fri Mar 05 2021 Silvan Calarco <silvan.calarco@mambasoft.it> 2.3-4mamba
+- use /usr/bin/bash insted of /usr/bin/sh in posttrans script
+- add triggerpostun to try to fix further problems
+
+* Tue Mar 02 2021 Silvan Calarco <silvan.calarco@mambasoft.it> 2.3-3mamba
+- add -p /usr/bin/sh to posttrans as fix attempt for symlink disappearing after upgrade
+
+* Tue Mar 02 2021 Silvan Calarco <silvan.calarco@mambasoft.it> 2.3-2mamba
+- fix attempt for symlink disappearing after upgrade
+
+* Tue Mar 02 2021 Silvan Calarco <silvan.calarco@mambasoft.it> 2.3-1mamba
+- update to 2.3
+- migrate /bin and /sbin files to /usr/bin and /usr/sbin and make the former symlinks
+
 * Tue Nov 24 2020 Silvan Calarco <silvan.calarco@mambasoft.it> 2.2-21mamba
 - specfile fixes with recent rpm