Cacher is the code snippet organizer for pro developers

#! /usr/bin/env python

"""
Perform an online backup of a sqlite database using the backup API.
See: http://www.sqlite.org/backup.html
https://github.com/husio/python-sqlite3-backup
"""

from __future__ import print_function
import sys
from os import path, access, R_OK, W_OK

try:
    import sqlite3
except:
    print( "The Python module sqlite3 is required" )
    sys.exit(1)

try:
    import sqlitebck
except:
    print( "The Python module sqlitebck is required" )
    print( "Install it using pip install sqlitebck or from https://github.com/husio/python-sqlite3-backup" )
    sys.exit(1)

__author__ = "Corey Gilmore"
__contact__ = "http://github.com/cfg/"
__version__ = "1.0"
__since__ = "2013-08-13"
__status__ = "Development"

def usage(args):
    print( "Usage: {0} <src db file> <dest db file>".format( args[0] ) )

if __name__ == '__main__':
    if len(sys.argv) != 3:
        usage(sys.argv)
        sys.exit(1)
    src_file = sys.argv[1]
    dest_file = sys.argv[2]

    if path.isfile(src_file) != True and access(src_file, R_OK) != True:
        print( "Error: Source file '{0}' does not exist or is not readable.".format(src_file) )
        usage(sys.argv)
        sys.exit(1)

    if path.isdir(dest_file) or (path.isfile(dest_file) == True and access(dest_file, W_OK) != True):
        print( "Error: Destination '{0}' is a directory or is not writable.".format(dest_file) )
        usage(sys.argv)
        sys.exit(1)

    # open the destination db on disk
    dest = sqlite3.connect(dest_file)
    # open an in-memory db
    mem = sqlite3.connect(':memory:')
    # finally open our source db
    src = sqlite3.connect(sys.argv[1])

    # copy from source to memory, close the source. get in and out as fast as possible.
    sqlitebck.copy(src, mem)
    src.close()

    # copy from memory to disk, close.
    sqlitebck.copy(mem, dest)
    mem.close()
    dest.close()