/usr/bin/findindir

#!/usr/bin/env bash

GREP="/usr/bin/grep"
XARG="/usr/bin/xargs"
PATH=$1
EXT=$2

CMD="$GREP -l -r --include=\*.$EXT $3 $PATH"

for VAR in "${@:3}"
do
    if [ -n "$VAR" ]; then
        CMD="$CMD | $XARG $GREP -l $VAR"
    fi
done

/bin/bash -c "$CMD"