diff --git a/rechnung.sh b/rechnung.sh
index b0c8d3f..1d2fc7d 100755
--- a/rechnung.sh
+++ b/rechnung.sh
@@ -24,7 +24,7 @@ RUBBER_BIN=$(which rubber 2>/dev/null || echo "rubber")
 EXECUTABLES_TO_CHECK="$BC_BIN $TR_BIN $SED_BIN $CUT_BIN $TPUT_BIN $DATE_BIN $PDFLATEX_BIN $RUBBER_BIN"
 
 GENPDF=""
-if [ -x $RUBBER_BIN ]; then
+if [ -x "$RUBBER_BIN" ]; then
     GENPDF="$RUBBER_BIN -d "
 else
     GENPDF="$PDFLATEX_BIN -halt-on-error "
@@ -58,11 +58,11 @@ LFDNR=""
 
 NUMBER_OF_COLORS=$($TPUT_BIN colors)
 COLORED_OUTPUT=0
-RED="\\033[1;31m"
-GREEN="\\033[1;32m"
-YELLOW="\\033[1;33m"
-BLUE="\\033[1;34m"
-NORMAL="\\033[0;39m"
+RED="$(tput bold)$(tput setaf 1)"
+GREEN="$(tput bold)$(tput setaf 2)"
+YELLOW="$(tput bold)$(tput setaf 3)"
+BLUE="$(tput bold)$(tput setaf 4)"
+NORMAL="$(tput bold)$(tput sgr0)"
 
 
 # Diverse Checks
@@ -70,7 +70,7 @@ NORMAL="\\033[0;39m"
 
 check_readable() {
     
-    printf "\n[+] Datei \"$1\" ist lesbar ..."
+    printf "\n[+] Datei %s ist lesbar ..." "$1"
     if [ -f "$1" ] && [ -r "$1" ]
     then
         print_ok
@@ -82,14 +82,14 @@ check_readable() {
 
 check_binaries() {
 
-    local program=""
-    local binaries=$*
+    program=""
+    binaries=$*
     
     for program in $binaries; do
-        printf "\n[+] Suche nach Programm $program ..."
+        printf "\n[+] Suche nach Programm %s ..." "$program"
         if [ ! -x "$program" ]; then
             print_failed
-            printf "\n[-] Das Programm \"$program\" wird benötigt, aber nicht gefunden."
+            printf "\n[-] Das Programm \"%s\" wird benötigt, aber nicht gefunden." "$program"
             quit 3
         else
             print_ok
@@ -99,7 +99,7 @@ check_binaries() {
 
 is_option() (
 
-    local line="$*"
+    line="$*"
     
     if [ "${line#*=}" != "$line" ]; then
         return 0
@@ -114,7 +114,7 @@ is_option() (
 print_failed() {
 
     if [ "$COLORED_OUTPUT" -eq 1 ]; then
-        printf "$RED Failed$NORMAL"
+        printf "%s Failed%s" "$RED" "$NORMAL"
     else
         printf " Failed"
     fi
@@ -123,7 +123,7 @@ print_failed() {
 print_ok() {
 
     if [ "$COLORED_OUTPUT" -eq 1 ]; then
-        printf "$GREEN OK$NORMAL"
+        printf "%s OK%s" "$GREEN" "$NORMAL"
     else
         printf " OK"
     fi
@@ -131,12 +131,12 @@ print_ok() {
 
 print_warn() {
 
-    local msg=$*
+    msg=$*
 
     if [ "$COLORED_OUTPUT" -eq 1 ]; then
-        echo -e "$YELLOW[-]$NORMAL $msg"
+        echo "$YELLOW[-]$NORMAL $msg"
     else
-        echo -e "[-] $msg"
+        echo "[-] $msg"
     fi
 }
 
@@ -146,7 +146,7 @@ print_warn() {
 trim_line() {
     
     set -f
-    set -- $*
+    set -- "$*"
     LINE_BUFFER=$(printf '%s' "$*")
     set +f
 }
@@ -154,7 +154,7 @@ trim_line() {
 trim_key() {
 
     set -f
-    set -- $*
+    set -- "$*"
     KEY_BUFFER=$(printf '%s' "$*")
     set +f
 }
@@ -162,7 +162,7 @@ trim_key() {
 trim_value() {
 
     set -f
-    set -- $*
+    set -- "$*"
     VALUE_BUFFER=$(printf '%s' "$*")
     set +f
 }
@@ -170,7 +170,7 @@ trim_value() {
 
 reset_values() {
 
-    echo -e "\n[+] Initialisiere Felder für Rechnung neu."
+    printf "\n[+] Initialisiere Felder für Rechnung neu."
     LINE_BUFFER=""
     KEY_BUFFER=""
     VALUE_BUFFER=""
@@ -187,11 +187,11 @@ reset_values() {
 
 set_value() {
     
-    local key=$(echo "$*" | $CUT_BIN -d "=" -f1)
-    local value=$(echo "$*" | $CUT_BIN -d "=" -f2)
+    key=$(echo "$*" | $CUT_BIN -d "=" -f1)
+    value=$(echo "$*" | $CUT_BIN -d "=" -f2)
     
-    trim_key $key
-    trim_value $value
+    trim_key "$key"
+    trim_value "$value"
     case $KEY_BUFFER in
         kunde) KUNDE="$VALUE_BUFFER";;
         adresse) ADRESSE="$VALUE_BUFFER";;
@@ -207,20 +207,20 @@ set_value() {
 
 make_invoice() {
 
-    local dead_days="14"
-    if [ $(date +%u) -gt 5 ]; then
+    dead_days="14"
+    if [ "$(date +%u)" -gt 5 ]; then
 	dead_days="16"
     fi
     
-    local month_ascii=$(date '+%B')
-    local inv_day=$(date '+%j')
-    local inv_date=$(date '+%Y%m%d')
-    local inv_dead=$(date -d "+${dead_days}days" '+%d.\\\\,%m.\\\\,%Y')
-    local rechnungsnummer="$inv_date--$LFDNR"
-    local subject="Rechnung zu $SHORT"
-    local filename="$(date '+%Y%m%d')_Rechnung_$(echo "$month_ascii")_$(echo "$KUNDE" | $TR_BIN " " "_").ltx"
-    local buffer="$KUNDE; $ADRESSE"
-    local anschrift="$(echo "$buffer" | sed 's/; /\\\\\\\\\\\\\\ /g')"
+    month_ascii=$(date '+%B')
+    inv_day=$(date '+%j')
+    inv_date=$(date '+%Y%m%d')
+    inv_dead=$(date -d "+${dead_days}days" '+%d.\\\\,%m.\\\\,%Y')
+    rechnungsnummer="$inv_date--$LFDNR"
+    subject="Rechnung zu $SHORT"
+    filename="$(date '+%Y%m%d')_Rechnung_$(echo "$month_ascii")_$(echo "$KUNDE" | $TR_BIN " " "_").ltx"
+    buffer="$KUNDE; $ADRESSE"
+    anschrift="$(echo "$buffer" | sed 's/; /\\\\\\\\\\\\\\ /g')"
 
     echo "[+] Erstelle Rechnung: $filename"
     echo -n "s!#SUBJECT#!" >$SEDFILE; echo "$subject!" >>$SEDFILE
@@ -231,11 +231,11 @@ make_invoice() {
     echo -n "s!#POSITION#!" >>$SEDFILE; echo "$POSITION!" >>$SEDFILE
     echo -n "s!#BETRAG#!" >>$SEDFILE; echo "$BETRAG!" >>$SEDFILE
     echo -n "s!#DEADLINE#!" >>$SEDFILE; echo "$inv_dead!" >>$SEDFILE
-    cp $TEMPLATEFILE $filename
-    $SED_BIN -i -f $SEDFILE $filename
-    $GENPDF $filename
-    if [ -x $RUBBER_BIN ]; then
-	$RUBBER_BIN --clean $filename
+    cp "$TEMPLATEFILE" "$filename"
+    $SED_BIN -i -f "$SEDFILE" "$filename"
+    $GENPDF "$filename"
+    if [ -x "$RUBBER_BIN" ]; then
+	"$RUBBER_BIN" --clean "$filename"
     fi
 
     if [ $? -eq 0 ]; then
@@ -247,8 +247,8 @@ make_invoice() {
 
 proced_ini_line() {
     
-    local line=$*
-    local first=$(echo "$line" | cut -c1-1)
+    line=$*
+    first=$(echo "$line" | cut -c1-1)
 
     # leerzeilen ignorieren
     if [ "$line" = "" ]; then
@@ -273,10 +273,10 @@ proced_ini_line() {
     
     # alle anderen zeilen
     else
-        is_option $line
+        is_option "$line"
         if [ $? -eq 0 ]
         then
-            set_value $line
+            set_value "$line"
         else
             print_warn "Invalid syntax: $line"
         fi
@@ -284,9 +284,10 @@ proced_ini_line() {
 }
 
 quit() {
-    printf "\n$BLUE"
-    printf "[-] Exit$NORMAL\n"
-    exit $1
+    printf "\n"
+    print "$BLUE"
+    printf "[-] Exit%s\n" "$NORMAL"
+    exit 1
 }
 
 
@@ -297,24 +298,24 @@ echo "= Rechnung v$PROGRAMM_VERSION ="
 echo "==================="
 
 # Verschiedene Basic Checks
-if [ -n $NUMBER_OF_COLORS ] && [ "$NUMBER_OF_COLORS" -ge 8 ]; then
+if [ -n "$NUMBER_OF_COLORS" ] && [ "$NUMBER_OF_COLORS" -ge 8 ]; then
     COLORED_OUTPUT=1
 fi
 
-if [ $(id -u) -eq 0 ]; then
+if [ "$(id -u)" -eq 0 ]; then
     echo "$0: Das Skript darf nicht als Root ausgeführt werden."
     exit 1
 fi
-check_binaries $EXECUTABLES_TO_CHECK
-check_readable $RECHNUNGSFILE
-check_readable $TEMPLATEFILE
+check_binaries "$EXECUTABLES_TO_CHECK"
+check_readable "$RECHNUNGSFILE"
+check_readable "$TEMPLATEFILE"
 printf "\n"
 
 # Kundendatei einlesen und rechnungen erstellen
 while IFS= read -r rawline
 do
-    trim_line $rawline
-    proced_ini_line $LINE_BUFFER
-done <$RECHNUNGSFILE
+    trim_line "$rawline"
+    proced_ini_line "$LINE_BUFFER"
+done < "$RECHNUNGSFILE"