AttributeError: 'str' object has no attribute 'format' : Crontab error

I have a cronjob set that runs 00:00 GMT everyday.This cronjob executes a shell script which calls a python script inteally.The python script generates a log file as output.The shell script and python script are located in the same directory in the unix box(/abc/logs/env/pqr/hvi/). They have 777 as permission.Now, when i run the shell script from this location(/abc/logs/env/pqr/hvi/) it executes fine and the python script inteally gets called & generates the log file.But when this is executed through the cronjob , the output file is not generated and I get a error message saying "AttributeError: 'str' object has no attribute 'format' " When I do a which python I get : somelocation/../thirdparty/python/2.6/bin/python So I think I am using python 2.6 which supports .format operation. My guesses here are:

1. Python interpreter issue for which I added below to cronjob:

   PYTHONPATH =/cs/imf/dist/thirdparty/python/2.6/bin/python PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin

But no luck

2. Python version issue as it might not be supporting '.format' function of datetime. But I guess I am using Python2.6 ( which python shows 2.6) & it supports this function of datetime.

Not sure where the issue is. Can anyone please help? Thanks in advance.

Cron Job looks like :

PYTHONPATH =/cs/../../thirdparty/python/2.6/bin/python
PATH=/usr/bin:/bin:/usr/sbin:/sbin:/usr/local/bin
31 05 * * 2,3,4,5,6  /abc/logs/env/pqr/hvi/calculate_latency.sh  > /var/tmp/hvi_latency.log 2>&1

Shell script looks like:

#!/usr/bin/ksh
cd /abc/logs/env/pqr/hvi/
NOW=$(date +"%F")
FILE="hvi-latency-$NOW.log"
zgrep "Received message:" $(date -d '-2 day' '+%Y%m%d')*.hvi.data.log.gz $(date -d'yesterday' +%Y%m%d)/*.data.* | cut -d' ' -f1,2,20,21,22 | sed 's/2016.*gz://' | sed 's/ /|/2'  > $FILE
chmod 777 $FILE
python /abc/logs/env/pqr/hvi/HVI_Delay_analyizer_BY_HOUR_usingDatetime.py $FILE /abc/logs/env/pqr/hvi/
chmod 777 HVI_MaxDelayPerHOUR.log
cut -d "|" -f2 HVI_MaxDelayPerHOUR.log >HVI_MaxDelay.log
chmod 777 HVI_MaxDelay.log
tail -n +2 HVI_MaxDelay.log > HVI_Latency.log
chmod 777 HVI_Latency.log
cat HVI_Latency.log > HVI_Latency.txt
chmod 777 HVI_Latency.txt
mail -s "DR Latency values for HVI feeder on date:$NOW" sajida.sayyad@gmail.com < HVI_Latency.txt

python script looks like:

import os
import sys
import time
import math
import re
from datetime import datetime
from datetime import timedelta

def get_timestamp():
import datetime
n = datetime.datetime.now()
# print n gives : 2016-03-25 04:08:43.123162
result = '{0:04}-{1:02}-{2:02}_{3:02}{4:02}{5:02}'.format(n.year,n.month,n.day,n.hour,n.minute,n.second)
# print result gives :2016-03-25_040843
retu result

Error message is:

[s109193@gblp2509261 tmp]$ tail -100 hvi_latency.log 
2016-03-25 05:31:43.806450
Traceback (most recent call last):
File "/abc/logs/env/pqr/hvi/HVI_Delay_analyizer_BY_HOUR_usingDatetime.py", line 119, in ?
START_TIME = get_timestamp()   
File "/abc/logs/env/pqr/hvi/HVI_Delay_analyizer_BY_HOUR_usingDatetime.py", line 18, in get_timestamp
result = '{0:04}-{1:02}-{2:02}_{3:02}{4:02}{5:02}'.format(n.year,n.month,n.day,n.hour,n.minute,n.second)
AttributeError: 'str' object has no attribute 'format'