Shell script for create Flutter sample project of given Widget

flutter_creater.sh

#!/bin/bash

if [ $# -ne 1 ]; then
  echo "USAGE: a single Widget name must be given as an argument. See example below" 1>&2
  echo "USAGE: sh flutter_creater.sh InkWell" 1>&2
  exit 1
fi

WIDGET_NAME=$1
WIDGET_NAME_LOWER=`echo ${WIDGET_NAME} | tr '[:upper:]' '[:lower:]'`
FOLDER_NAME="mysample_${WIDGET_NAME_LOWER}"

BASE_URL="https://api.flutter.dev/flutter/"
CATEGORY="material"

STATUS_CODE_MATERIAL=`curl -s ${BASE_URL}/${CATEGORY}/${WIDGET_NAME}-class.html -o /dev/null -w '%{http_code}\n' -s`

if [ $STATUS_CODE_MATERIAL -ne 200 ]; then
  CATEGORY="widgets"
fi

CREATE_COMMAND=`curl --silent https://api.flutter.dev/flutter/${CATEGORY}/${WIDGET_NAME}-class.html | grep snippet-create-command | sed 's/<span class="snippet-create-command">//' | sed 's/<\/span>//' | sed "s/mysample/${FOLDER_NAME}/"`

if [ -z "$CREATE_COMMAND" ]; then
  echo "ERROR: create command not found."
  exit 1
fi

# FIXME: `sh $CREATE_COMMAND` causes an error for some reason

curl --silent https://api.flutter.dev/flutter/${CATEGORY}/${WIDGET_NAME}-class.html | grep snippet-create-command | sed 's/<span class="snippet-create-command">//' | sed 's/<\/span>//' | sed "s/mysample/${FOLDER_NAME}/" | sh

cd $FOLDER_NAME
flutter run