sdcard-write: Colorize error message if possible

Signed-off-by: Andreas Müller <schnitzeltony@gmail.com>

scripts/sdcard-write/tools.inc

@@ -7,16 +7,46 @@
 # This script contains some helper functions and can be sourced by other 
 # scripts
 
+# set terminal styles
+# are we on terrminal?
+if [ -t 1 ] ; then
+    # tput available?
+    if [ ! "x`which tput 2>/dev/null`" = "x" ] ; then
+        # supports colors ?
+        ncolors=`tput colors`
+        if [ -n "$ncolors" -a  $ncolors -ge 8 ] ; then
+            style_bold="`tput bold`"
+            style_underline="`tput smul`"
+            style_standout="`tput smso`"
+            style_normal="`tput sgr0`"
+            style_black="`tput setaf 0`"
+            style_red="`tput setaf 1`"
+            style_green="`tput setaf 2`"
+            style_yellow="`tput setaf 3`"
+            style_blue="`tput setaf 4`"
+            style_magenta="`tput setaf 5`"
+            style_cyan="`tput setaf 6`"
+            style_white="`tput setaf 7`"
+        fi
+    fi
+fi
 
+ErrorOut() {
+    echo
+    echo "${style_red}${style_bold}${1}!${style_normal}"
+    echo
+    exit -1
+}
+
+# CheckPrerequisite checks if required hosttool is found on host. In case not
+# it outputs a message and exits script.
 CheckPrerequisite() {
-    if [ "x`which $1`" = "x" ] ; then
-        echo
-        echo "You need to install $1 first!"
-        echo
-        exit -1
+    if [ "x`which $1 2>/dev/null`" = "x" ] ; then
+        ErrorOut "You need to install $1 first!"
     fi
 }
 
+
 # SelectCardDevice() creates a dialog to select one of all available removable
 # devices. The path to the selected device is stored in the variale DevicePath.
 SelectCardDevice() {
@@ -59,8 +89,7 @@ SelectCardDevice() {
 	done
 	
 	if [ $iCount -eq 0 ]; then
-		echo 'No removable devices found!'
-		exit 1
+		ErrorOut 'No removable devices found!'
 	fi
 
 	dialog --title 'Select card device'\