小编Sup*_*eme的帖子

我正在尝试将变量的输出重定向并写入文件,但只有输出的最后一行显示在我正在写入的文件中.但是当我对变量进行打印时,我会得到所有我期望的行.

rds = boto3.client('rds')
rds_instances = rds.describe_db_instances()['DBInstances']
for databases in rds_instances:
    arns = ("{0}".format(databases['DBInstanceArn']))
#    print (arns)
f = open('/tmp/arns', 'a')
f.write(arns)
f.close()

我打印的示例输出我得到多个rds arn:

arn:aws:rds:us-east-1:222222222222:db:databasename01

arn:aws:rds:us-east-1:222222222222:db:databasename02

arn:aws:rds:us-east-1:222222222222:db:databasename03

但是,当我检查文件时,我写的只有:

arn:aws:rds:us-east-1:222222222222:db:databasename03