flask: not found になってしまう。

お世話になります。以下のようなシェルを実行すると
flask: not found になってしまいます。（↓↓)
flaskはインスールしているか確認しました。(↓↓↓)

本の指示通りやってます。ネットで検索してしても、誤記訂正は載ってませんでした。
何が問題なのでしょうか？

#!/usr/bin/env sh
cd /home/pi/toku1/12-15-a4
pid=`pgrep -f "python3 datalogger_weather.py"`
if [ $? -eq 0 ]; then
    echo "datalogger_weather.py is running"
else
    python3 datalogger_weather.py &
fi
FLASK_DEBUG=1 FLASK_APP=server_12_datalogger_weather.py flask run -h 0.0.0.0  ＜＝＝ここ

pi@raspberrypi:~/toku1/12-15-a4 $ sh run_12_datalogger_weather.sh
run_12_datalogger_weather.sh: 10: run_12_datalogger_weather.sh: flask: not found  ＜＝＝エラー
pi@raspberrypi:~/toku1/12-15-a4 $ insert:
	AirPressure: None, 2017-09-02 04:03:18.177560+00:00, 1002.2417428411286
	Humidity: None, 2017-09-02 04:03:18.177820+00:00, 40.46317978782877
	Temperature: None, 2017-09-02 04:03:18.177991+00:00, 32.35179667515331

insert:

pi@raspberrypi:~/toku1/12-15-a4 $ sh install_libs222.sh 
Requirement already satisfied (use --upgrade to upgrade): Flask in /usr/lib/python3/dist-packages (from -r /home/pi/toku1/12-15-a4/requirements222.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): Flask-SQLAlchemy in /usr/local/lib/python3.4/dist-packages (from -r /home/pi/toku1/12-15-a4/requirements222.txt (line 2))
Requirement already satisfied (use --upgrade to upgrade): Werkzeug>=0.7 in /usr/lib/python3/dist-packages (from Flask->-r /home/pi/toku1/12-15-a4/requirements222.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): Jinja2>=2.4 in /usr/lib/python3/dist-packages (from Flask->-r /home/pi/toku1/12-15-a4/requirements222.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): itsdangerous>=0.21 in /usr/lib/python3/dist-packages (from Flask->-r /home/pi/toku1/12-15-a4/requirements222.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): markupsafe in /usr/lib/python3/dist-packages (from Jinja2>=2.4->Flask->-r /home/pi/toku1/12-15-a4/requirements222.txt (line 1))
Cleaning up...