Simplistic URL encoding for Busybox shell.

urlencode.sh

#!/bin/sh

echo "$@" | awk -v ORS="" '{ gsub(/./,"&\n") ; print }' | while read l;
do
  case "$l" in
    [-_.~a-zA-Z0-9] ) echo -n ${l} ;;
    "" ) echo -n %20 ;;
    * )  printf '%%%02X' "'$l"
  esac
done
echo ""