#!/bin/dash

busybox_has() {
   builtin command -v busybox >/dev/null ||
      return 1

   # Sanitize searches for '[' and '[['
   a=$1
   a=${a//[/\\[}

   if [[ "$1" = "[" ]]; then
      busybox | egrep -oq $'\t'"($a)[,[:space:]]" ||
         return 1
   else
      busybox | egrep -oq "[[:space:]]($a)[,]?" ||
         return 1
   fi
}