os.linesep字符串给出当前平台使用的行终止符。例如，Windows使用\'\r\n\'，Linux使用\'\n\'而Mac使用\'\r\'。
def write_file(filename, subdomains):
# saving subdomains results to output file
print("%s[-] Saving results to file: %s%s%s%s" % (Y, W, R, filename, W))
with open(str(filename), \'wt\') as f:
for subdomain in subdomains:
f.write(subdomain + os.linesep)
输出：
www.yahoo.com uk.118800.yahoo.com 360.yahoo.com img.3721.yahoo.com ads.yahoo.com cms.analytics.yahoo.com tag.idsync.analytics.yahoo.com sp.analytics.yahoo.com ups.analytics.yahoo.com