Small script for writting dump files of tcpdump

tcpdump.py

import subprocess
import datetime

today = datetime.datetime.now()
dump_file = ('dumped/' + today + '.txt') 

def write_dump():
    try:
	a = subprocess.check_output(['tcpdump'])
	dump = open(dump_file 'w')
	dump.write(a)
	written = True
	dump.close()
	print 'Sucessfully dumped info'
    except:
	print 'error while trying to write dump'
		
if __name__=="__main__":
    write_dump()