improve mkusb.sh

mkusb.sh

@@ -1,9 +1,6 @@
 # name of the USB stick to be created
 NAME=BOOT_TINY
 
-if [ ! -d boot_tiny ] ; then
-  git clone --depth 1 git@gitlab.psi.ch:samenv/boot_tiny.git
-fi
 # list removeable disks
 DISKS=()
 while read LINE
@@ -22,9 +19,16 @@ done < <(lsblk -l --output RM,TYPE,NAME,SIZE,LABEL,VENDOR,MODEL)
 echo "which device? should be one of: ${DISKS[@]}"
 read DEVICE
 
+if [ -z $DEVICE ] ; then
+  exit
+fi
 if [[ " ${DISKS[@]} " =~ " $DEVICE " ]]; then
   echo "create TinyLinux"
 
+  if [ ! -d boot_tiny ] ; then
+    git clone --depth 1 git@gitlab.psi.ch:samenv/boot_tiny.git
+  fi
+
   if [[ $(cat /sys/block/$DEVICE/removable) != "1" ]]; then
     echo "/dev/$DEVICE is not a removable disk"
     exit