diff --git a/UpdateRootfs.sh.in b/UpdateRootfs.sh.in
index af10b8a..26a41b3 100644
--- a/UpdateRootfs.sh.in
+++ b/UpdateRootfs.sh.in
@@ -641,7 +641,13 @@ cat << XEOF
 
 CALLDIR=\`pwd\`
 WRKDIR=/opt/GfA/SDUpdateTool
-  
+
+if [ -z "\$1" ]; then
+    CUSTOM_ROOT=\$WRKDIR/custom_root
+else
+    CUSTOM_ROOT=\$WRKDIR/\$1
+fi  
+
 DESTDEV="/dev/mmcblk1"
 
 EMMC_BOOTPATH="/tmp/EMMCBOOT"
@@ -702,6 +708,14 @@ then
         rm \$GFA_PREFIX/etc/wpa_supplicant/wpa_supplicant.conf
 fi
 
+#=== execute custom_pre script =====
+GFA_NEWROOTFS=\$WRKDIR/_BootRoot
+if [ -x "\$WRKDIR/custom_pre.sh" ]; then
+  SAVEDIR=\`pwd\`
+  \$WRKDIR/custom_pre.sh \$EMMC_ROOTPATH \$GFA_NEWROOTFS
+  cd \$SAVEDIR
+fi
+
 #=== copy ROOTFS
 cd \$WRKDIR/_BootRoot
 rsync -avR --exclude=/_GfABoot \\
@@ -794,7 +808,7 @@ then
         sed -i 's/TSYNCCMD=rdate time.memod.de/TSYNCCMD=\/etc\/init.d\/S99rtc_GfA set/' \$GFA_PREFIX/var/GfA/Display_GSM.ini
 fi
 #================================
-#--create mountable run folder insted of link
+#--create mountable run folder instead of link
 RUNDIR=\$GFA_PREFIX/run
 if [ -L \$RUNDIR ]; then
   mv \$RUNDIR \$RUNDIR'_WRK'
@@ -839,12 +853,18 @@ chown -Rv \${UID_PG}:\${GID_PG} \$GFA_PREFIX/var/lib/pgsql
 
 chmod 700 \$GFA_PREFIX/root/.ssh
 #===== copy custom_root files if folder exists
-if [ -d "\$WRKDIR/custom_root" ]; then
-  cd \$WRKDIR/custom_root
+if [ -d "\$CUSTOM_ROOT" ]; then
+  cd \$CUSTOM_ROOT
   rsync -avR  \\
    ./ \$EMMC_ROOTPATH/
 fi
 #==============================================================================
+#=== execute custom_post script =====
+if [ -x "\$WRKDIR/custom_post.sh" ]; then
+  SAVEDIR=\`pwd\`
+  \$WRKDIR/custom_post.sh \$EMMC_ROOTPATH \$GFA_NEWROOTFS
+  cd \$SAVEDIR
+fi
 #=== copy BOOTFS
 rm -rf \$EMMC_BOOTPATH/*
 cd \$WRKDIR/_BootRoot/_GfABoot
@@ -941,17 +961,25 @@ fi
 #===== MakeSDUpdateTool === End
 
 #====== HELP on unknown Command =======
-echo -e "Unknown Command :: $1"
-echo -e "Usage: $0 \e[32m[Command]\e[0m"
-echo -e "\t without command ... update to new system"
-echo -e "\t \e[32mMakeBootableSD\e[0m ... create bootable SD card with factory defaults"
-echo -e "\t \e[32mMakeBootableEMMC\e[0m ... create bootable EMMC with factory defaults"
-echo -e "\t \e[32mMakeSDUpdateTool\e[0m ... create Folders and scripts for"
-echo -e "\t\t updating system from SD Card in /opt/GfA/SDUpdateTool"
-echo -e "\t\t To Do UpdateEMMC:"
-echo -e "\t\t\t cd /opt/GfA/SDUpdateTool"
-echo -e "\t\t\t ./UpdateEMMC.sh"
-echo -e "\t\t\t if folder /opt/GfASDupdateTool/custom_root exists"
-echo -e "\t\t\t whole tree will be copied to root filesystem as is"
-
+if [ $# > 1 ]; then
+  echo -e "Unknown Command :: $1"
+  echo -e "Usage: $0 \e[32m[Command]\e[0m"
+  echo -e "\t without command ... update to new system"
+  echo -e "\t \e[32mMakeBootableSD\e[0m ... create bootable SD card with factory defaults"
+  echo -e "\t \e[32mMakeBootableEMMC\e[0m ... create bootable EMMC with factory defaults"
+  echo -e "\t \e[32mMakeSDUpdateTool\e[0m ... create Folders and scripts for"
+  echo -e "\t\t updating system from SD Card in /opt/GfA/SDUpdateTool"
+  echo -e "\t\t To Do UpdateEMMC:"
+  echo -e "\t\t\t cd /opt/GfA/SDUpdateTool"
+  echo -e "\t\t\t ./UpdateEMMC.sh [custom_root_path relative to /opt/GfA/SDUpdateTool]"
+  echo -e "\t\t\t 	default ... custom_root"
+  echo -e "\t\t\t if folder /opt/GfASDupdateTool/custom_root exists"
+  echo -e "\t\t\t whole tree will be copied to root filesystem as is"
+  echo -e "\t\t\t if script (+x) /opt/GfASDupdateTool/custom_pre.sh exists"
+  echo -e "\t\t\t script will be called with parameters \$1=PATH_TO_EXISTING_ROOTFS \$2=PATH_TO_NEW_ROOTFS"
+  echo -e "\t\t\t before copy to EMMC starts"
+  echo -e "\t\t\t if script (+x) /opt/GfASDupdateTool/custom_post. exists"
+  echo -e "\t\t\t script will be called with parameters \$1=PATH_TO_EXISTING_ROOTFS \$2=PATH_TO_NEW_ROOTFS"
+  echo -e "\t\t\t after copy to EMMC is finished"
+fi
 exit 0