Python - Add Date Stamp To Text File

import datetime

f=open("/home/rohitsai/Documents/acs.txt",'a')
f.write ("heloo"+'\t')
f.write(datetime.datetime.now().ctime())
print datetime.datetime.now()

this code will add helo as well as current date on same file. 'a' is for append mode, \t for tab space.

This will prepend a timestamp to the front of the filename:

from datetime import datetime

# define a timestamp format you like
FORMAT = '%Y%m%d%H%M%S'
path = 'foo.txt'
data = 'data to be written to the file\n'
new_path = '%s_%s' % (datetime.now().strftime(FORMAT), path)
open(new_path, 'w').write(data)

import datetime

def timeStamped(fname, fmt='%Y-%m-%d-%H-%M-%S_{fname}'):
    return datetime.datetime.now().strftime(fmt).format(fname=fname)

with open(timeStamped('myfile.txt'),'w') as outf:
    outf.write('data!')