Q: BigsqlPostgres pg_dump command using crons in ubuntu not working I am using Ubuntu 16.04 xenial. And on ubuntu machine i installed BigsqlPostgres version 10. Which is installed in directories as follows:
BigsqlPostgres:
/etc/bigsql/pg10/bin/
/etc/bigsql/data/ 

I am using below scripts for taking a backup of database:
import os, boto3, pytz, sys

parent_dir = os.path.dirname(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
sys.path.append(parent_dir)

from sellerhub_midport.utils.variables import _POSTGRES_HOST, _POSTGRES_PORT, _POSTGRES_USERNAME, _POSTGRES_PASSWORD, _POSTGRES_DBNAME, _AWS_ACCESS_KEY_ID, _AWS_SECRET_KEY, _BUCKET_NAME
from datetime import datetime


class BackupDatabase(object):
    """docstring for BackupDatabase"""
    def __init__(self):
        super(BackupDatabase, self).__init__()
        localtz = pytz.timezone('UTC')
        self.filename = 'report'+datetime.now(localtz).strftime('%Y_%m_%d') + '.dump'
        self.pathname = 'prod_backup/' + self.filename
        self.backup_database()

    def backup_database(self):
        os.putenv('PGPASSWORD', _POSTGRES_PASSWORD)
        os.system('/etc/bigsql/pg10/bin/pg_dump --format=c -h {} -p 5432 -d {} -U {} > {}'.format(_POSTGRES_HOST, _POSTGRES_DBNAME, _POSTGRES_USERNAME, self.filename))
        boto3_res = boto3.resource(service_name='s3', aws_access_key_id=_AWS_ACCESS_KEY_ID, aws_secret_access_key=_AWS_SECRET_KEY,)
        with open(self.filename, 'rb') as f_obj:
            boto3_res.Bucket(_BUCKET_NAME).put_object(Key=self.pathname, Body=f_obj)
        os.remove(self.filename)

BackupDatabase()

If i run above backup.py file in my django virtual environment it's create a backup file named with current timestamp.But when i write a cron job for the same it is not working, i mean not creating a backup of database but when i run this file manually its working fine. Below is cron which i write for taking backup of database.
10 14 * * * /usr/bin/python /home/ekodev/sellerhub_midport/sellerhub_midport/scripts/service_crons/backup_db.py > /tmp/listener.log 2>&1

I am not getting any log error. If i look into the /tmp/listener.log its showing me system is ok only. 
THANKS FOR YOUR PRECIOUS TIME.

A: If a script works when you execute manully and not working when execute though cron, Generally it means that there is difference in environment variables.
What I would suggest is to make the script environment variable independent.
For troubleshooting, try defining the variables and values within the script OR try printing it before using.
