diff --git a/git_helpers b/git_helpers
index be969d4..c3ff404 100755
--- a/git_helpers
+++ b/git_helpers
@@ -62,14 +62,14 @@ revert_to_commit_before_pull () {
 clone_customer_repository () {
     local func="${FUNCNAME[0]}"
     if [ "$PWD" = "$working_directory" ]; then
-        if ! [[ -d $workspace_dir ]]; then
+        if ! [[ -d "./$workspace_dir" ]]; then
             { mkdir -p ./$workspace_dir; }
         fi
         # check if the directory is empty. If so, clone the
         # customer repository
         if ! find ./$workspace_dir -mindepth 1 -maxdepth 1 | read; then
             log_debug "$func:${LINENO} cloning ${1} ..."
-            if { cd ./$workspace_dir ; }; then
+            if { cd "./$workspace_dir" ; }; then
                 $(exec_git_command git clone "$1")
                 if [ $? -eq 0 ]; then
                     log_debug "$func:${LINENO} cloning ${1} done"
@@ -80,7 +80,7 @@ clone_customer_repository () {
         else
             # the directory is not empty, so we assume the
             # customer-repository has been cloned already
-            if ! [[ -d ./${workspace_dir}/$customer_id ]]; then
+            if ! [[ -d "./${workspace_dir}/$customer_id" ]]; then
                 log_fatal "$func:${LINENO} "\
                     "wrong repository: $(ls -d './${workspace_dir}/*')"
             else
@@ -147,12 +147,22 @@ pull_customer_repository () {
         return 1
     fi
 
-    # see 'man -Pless\ +/parameter/pattern/string/bash'
+    # see https://www.gnu.org/
+    #           software/bash/manual/html_node/Shell-Parameter-Expansion.html
+    # [...]
+    #   
+    #    ${parameter//pattern/string}
+    #
+    # If there are two slashes separating parameter and pattern (...),
+    # all matches of pattern are replaced with string.
+    # 
+    # If the expansion of string is null, matches of pattern are deleted.
+    # [...]
     git_result=${git_result//[$'\r\n\t']/ }
 
     log_debug "$func:${LINENO} git-pull-result=${git_result}"
 
-    if grep -qE "^Already\s+\up\s+\to\s+date.*$" <<< $git_result; then
+    if grep -qE "^Already\s+\up\s+\to\s+date.*$" <<< "$git_result"; then
         log_warn "$func:${LINENO}: repository $PWD already up to date."
         read $1 <<< 'yes'
         cd_home ; return 1
@@ -237,6 +247,8 @@ changed_file_names () {
         local file_names=""
         local known_files=(update.conf current.conf emp.conf)
         known_files=(${known_files[@]} device.conf printer.conf opkg_commands) 
+        known_files=(${known_files[@]} ATBQT.ini sysconfig.ini ISMASMgr.ini) 
+        known_files=(${known_files[@]} SystemControl.ini) 
         for f in ${known_files[@]} ; do 
             if grep -qE ".*/${f}\s+.*" <<< $git_res; then
                 if ! [ -z $file_names ]; then