#!/usr/bin/python
# -*- coding: utf-8 -*-
import config, os, sys

if os.path.isfile(config.dbfile()):
	print 'Database file "{0}" already exists in current folder'.format(config.filename)
	if '-f' not in sys.argv:
		print 'Can`t install.'
		quit()
	else:
		print '-f (force) parameter set, deleting the file.'
		try: # -- так?
			os.remove(config.dbfile())
		except:
			'Can`t delete existing file. Installation cancelled.'

import db

db.conn.execute('CREATE TABLE operation (a INTEGER)')
db.conn.commit()

$ sudo gedit x.sqlite
$ ./install.py

$ ./install.py -f
Database file "x.sqlite" already exists in current folder
-f (force) parameter set, deleting the file.

$ ./install.py -f
Database file "x.sqlite" already exists in current folder
-f (force) parameter set, deleting the file.
Traceback (most recent call last):
  File "./install.py", line 17, in <module>
    import db
  File "************/db.py", line 3, in <module>
    conn = sqlite3.connect(config.dbfile())
sqlite3.OperationalError: unable to open database file

		try:
			os.remove(config.dbfile())
		except:
			print 'Can`t delete existing file. Installation cancelled.'
			quit()

try:
    os.remove(config.dbfile())
except(OSError):
    print 'Can`t delete existing file. Installation cancelled.'
    quit()