python - 尝试在子进程中调用 bash 脚本时，我被拒绝了权限

Question

我正在尝试在我的 python 脚本中运行 bash 脚本，我确信有一种方法可以代替我的 bash 脚本在 python 中执行的操作，但我更专注于让它工作。

这是我以 root 身份运行的代码，后面是错误:

import subprocess
#variable = subprocess.check_output('dmidecode', shell=True)
#print(variable)
#run program once as root then cron it as root
try :
    file = open("/var/log/serialcontrol/dmidecode.txt", "r")
except FileNotFoundError:
    file = open('/var/tmp/serialcontrol.bash', 'w') 
    file.write("#!/bin/bash/\nif [ ! -d /var/log/serialcontrol/]\nthen\n\tmkdir /var/log/serialcontrol/\nfi");
    file.close()
    subprocess.call("/var/tmp/serialcontrol.bash")

这里是错误

Traceback (most recent call last):
  File "/home/trisimix/serialcontrol/serialcontrol.py", line 6, in <module>
    file = open("/var/log/serialcontrol/dmidecode.txt", "r")
FileNotFoundError: [Errno 2] No such file or directory: '/var/log/serialcontrol/dmidecode.txt'

During handling of the above exception, another exception occurred:

Traceback (most recent call last):
  File "/home/trisimix/serialcontrol/serialcontrol.py", line 11, in <module>
    subprocess.call("/var/tmp/serialcontrol.bash")
  File "/usr/lib/python3.5/subprocess.py", line 557, in call
    with Popen(*popenargs, **kwargs) as p:
  File "/usr/lib/python3.5/subprocess.py", line 947, in __init__
    restore_signals, start_new_session)
  File "/usr/lib/python3.5/subprocess.py", line 1551, in _execute_child
    raise child_exception_type(errno_num, err_msg)
PermissionError: [Errno 13] Permission denied

Answer 1

您在处理 FileNotFoundError 时创建的 /var/tmp/serialcontrol.bash 文件不可执行。在尝试使用 subprocess 执行它之前先使其可执行。

import subprocess
import os
import stat

#variable = subprocess.check_output('dmidecode', shell=True)
#print(variable)
#run program once as root then cron it as root
try :
    file = open("/var/log/serialcontrol/dmidecode.txt", "r")
except FileNotFoundError:
    script = '/var/tmp/serialcontrol.bash'
    with open(script, 'w') as file:
        file.write("#!/usr/bin/env bash/\nif [ ! -d /var/log/serialcontrol/]\nthen\n\tmkdir /var/log/serialcontrol/\nfi");

    st = os.stat(script)
    os.chmod(script, st.st_mode | stat.S_IEXEC)

    subprocess.call(script)

作为@anishsane在评论中指出，chmod-ing 脚本的另一种替代方法是像这样调用它，然后删除 chmod:

subprocess.call(["/bin/bash", script])

实际上，如果我们可以假设 bash 在 PATH 上，那么这会更便携:

subprocess.call(["bash", script])