Python3 子进程和 if elif else 条件

Question

在生成用户 ID 信息的运行脚本下方，但是在搜索我有多个用户的文件时，它还会打印不存在的用户名，无法在 Linux id 命令中解析，例如：

from subprocess import Popen, PIPE

CRED = '\033[91m'
CGRN = '\033[92m'
CEND = '\033[0m'

with open("kkdiff", "r") as lid:
    for line in lid:
        line = line.strip()
        proc = Popen(['id', line], stdout=PIPE,)
        myID = proc.communicate()[0].decode('utf-8')
        if re.search(r'\bkoint\b', myID):
            print(line, CGRN + "Success: " + CEND + "User exists in the Group")
        else:
            print(line, CRED + "Failed: " + CEND + "User does not exists in the Group")

情况

id <username> results <no such user>
#id: user1: No such user    <-- This is ideal in Linux systems

因此，在使用带有 python 子进程模块的 id 命令时，它会在终端上返回相同的 #id: user1: No such user。但是它也返回user1 Failed: User does not exists in the Group，因为这是我在 else 语句中所要求的。

我们可以通过if, elif, else 得到它吗？比如：

如果找到单词然后"Sucess : user is in group"，elif no such user 然后"User is not the AD" 否则"Failed: user is not in group"

脚本输出：

id: user1: No such user
user1 Failed: User does not exists in the Group
user30 Success: User exists in the Group 
user81 Success: User exists in the Group  

期望的输出：

user1: No such user
user30 Success: User exists in the Group 
user81 Success: User exists in the Group 

Answer 1

您假设id 将消息写入标准输出。但是，实际上它是写到stderr中的。

$ id foo >/dev/null
id: ‘foo’: no such user
$ id foo 2>/dev/null
(empty output)

要访问 Popen'ed 进程的 stderr，请使用 proc.communicate()[1]。