I turned this into a full-blown project: http://www.gdub.rocks/

gw.sh

#!/bin/bash
# Find the system gradle executable to fall back on. 
GRADLE=$(which gradle)

# Default names for things
GRADLEW='gradlew'
BUILD_GRADLE='build.gradle'

GRADLEW_FOUND=false
BUILD_GRADLE_FOUND=false

CURR_PATH="${PWD}"

function error_exit() {
  echo "${@}" >&2
  exit 1
}

# First, search recursively upwards for a build.gradle.
# TODO: Make this smarter by parsing the args and use the provided buildfile if provided
until [[ "${CURR_PATH}" == "/" ]] || ${BUILD_GRADLE_FOUND}; do
  if [[ -e "${CURR_PATH}/${BUILD_GRADLE}" ]]; then
    BUILD_GRADLE_FOUND=true
    BUILD_GRADLE="${CURR_PATH}/${BUILD_GRADLE}"
  else 
    CURR_PATH=$(dirname "${CURR_PATH}")
  fi
done

# Fail fast if we don't find a build.gradle.
! ${BUILD_GRADLE_FOUND} && error_exit "Unable to find a ${BUILD_GRADLE} in any parent directory of ${PWD}." 

# Search recursively upwards from the first-found build.gradle for a gradlew.
until [[ "${CURR_PATH}" == "/" ]] || ${GRADLEW_FOUND}; do
  if [[ -x "${CURR_PATH}/${GRADLEW}" ]]; then
    GRADLEW_FOUND=true
    # Prefer the gradle wrapper if one exists in this tree.
    GRADLE="${CURR_PATH}/${GRADLEW}"
  else 
    CURR_PATH=$(dirname "${CURR_PATH}")
  fi
done

# Select the right gradle or error out if no good options exist.
if ${GRADLEW_FOUND}; then
  GRADLE_TYPE="wrapper"
elif [[ -x ${GRADLE} ]]; then
  GRADLE_TYPE="executable"
  echo "There is no ${GRADLEW} set up for this project. You may want to consider setting one up."
  echo "See: http://gradle.org/docs/current/userguide/gradle_wrapper.html"
else
  error_exit "Unable to find ${GRADLEW} or a gradle executable installed and available on your path."
fi

# Say what we are gonna do, then do it.
echo -e "Using gradle ${GRADLE_TYPE} at '${GRADLE}' to run '${BUILD_GRADLE}':\n"
cd $(dirname ${BUILD_GRADLE}) && "${GRADLE}" "${@}"

👍 Thank you, @dougborg! Your script will save me plenty of time, I'm sure.

@raindev: I just saw your comment. I now keep this updated @ http://www.gdub.rocks/

@dougborg, have you thought about looking not only for build.gradle but for settings.gradle as well?