fix: check existent of busybox

if dos2unix is not installed

src/script.sh

@@ -36,9 +36,16 @@ check_grep() {
 check_grep
 
 
-## Fallback to busybox dos2unix
-if ! command -v dos2unix &> /dev/null; then
-  alias dos2unix="busybox dos2unix"
+## Fallback to busybox's dos2unix if installed
+if ! command -v dos2unix &> /dev/null
+then
+  if command -v busybox &> /dev/null
+  then
+    alias dos2unix="busybox dos2unix"
+  else
+    echo "dos2unix or busybox not found"
+    exit 1
+  fi
 fi