Download CCleaner and extract

download_ccleaner.py

import re, requests, subprocess, os

"""
	Download CCleaner and extracting

	Tips: make 7z within PATH environment

	2014/04/22
	Inndy
"""

fnull = open(os.devnull)

def detect_7z():
	try:
		subprocess.call("7z", stdout = fnull)
		return True
	except:
		return False

def get_download_url(page_url):
	content = requests.get(page_url).content
	match = re.search(r'"(http://.+exe)"', content)
	if match == None:
		print "[-] Error: Pattern not found"
		return False
	else:
		return match.group(1)

def main():
	url = get_download_url("http://www.piriform.com/ccleaner/download/standard")
	if not url:
		print "[-] Error: Pattern not found"
		exit(1)

	print "[+] URL: %s" % url
	print "[+] Downloading..."
	f = open("ccleaner.exe", "wb")
	f.write(requests.get(url).content)
	f.close()
	print "[+] Download done!"

	if not detect_7z():
		print "[*] You need 7z to extract"
		exit()

	print "[+] Extracting"
	subprocess.call("mkdir ccleaner", shell = True, stderr = fnull, stdout = fnull)
	ret = subprocess.call([ \
		"7z", "x", "-y", "-occleaner", "ccleaner.exe", "Lang", \
		"CCleaner.exe", "CCleaner64.exe"], stderr = fnull, stdout = fnull)

	if ret == 0:
		print "[+] Done!"
		print "[+] Cleanup..."
		os.unlink("ccleaner.exe")
	else:
		print "[-] 7z returned status code %d" % ret

main()

fnull是做什麼用的?? 不懂