擅长:python、mysql、java
<p>您应该使用<code>with open(filename, mode) as f:</code>到<a href="https://docs.python.org/3/tutorial/inputoutput.html#reading-and-writing-files" rel="nofollow noreferrer">write to files</a>,确保即使发生异常也能关闭它们。你知道吗</p>
<p>一旦代码离开<code>with</code>下面的块,您的文件将自动关闭—无需手动关闭。你知道吗</p>
<p>您可以这样重新编写代码:</p>
<pre><code>rds = boto3.client('rds')
rds_instances = rds.describe_db_instances()['DBInstances']
with open('/tmp/arns', 'a') as f:
for databases in rds_instances:
arns = ("{0}".format(databases['DBInstanceArn']))
f.write(arns + '\n') # indented so it is executed foreach "for" loop
</code></pre>
<p>您也可以将<code>'\n'</code>添加到您的写入输出-它不会自动添加。你知道吗</p>