-if [ -n "$OPT_CONTENT" ]; then
- echo $OPT_CONTENT | /data/data/com.termux/files/usr/libexec/termux-api Notification "$@"
+if [ -v OPT_CONTENT ]; then
+ # Note that we want to accept an empty content (--content "").
+ echo ${OPT_CONTENT:=""} | /data/data/com.termux/files/usr/libexec/termux-api Notification "$@"