为什么此python脚本仅在从命令行运行时才会失败？

Question

I have a small python project that runs on a raspberry pi. It monitors temperatures, checks and sends emails, and controls a PDU. It runs perfectly from the Thonny IDE included in raspbian. However when I run it from the command line, or ideally on startup, it fails in one specific section of code dealing with checking emails.

I installed the email module on the system using pip install. Then I realized this was standard in python so i uninstalled it.

This is the error code.

Traceback (most recent call last):
  File "/home/pi/Documents/Python Files/Temp_Monitor_Project/temp_controller.py", line 122, in <module>
    main()
  File "/home/pi/Documents/Python Files/Temp_Monitor_Project/temp_controller.py", line 104, in main
    check_email_com(state_and_monitoring)
  File "/home/pi/Documents/Python Files/Temp_Monitor_Project/temp_controller.py", line 16, in check_email_com
    command = check_email.check_for_commands()
  File "/home/pi/Documents/Python Files/Temp_Monitor_Project/check_email.py", line 43, in check_for_commands
    command = message.checkMail()
  File "/home/pi/Documents/Python Files/Temp_Monitor_Project/check_email.py", line 20, in checkMail
    email_msg = email.message_from_bytes(data[0][1])
AttributeError: 'module' object has no attribute 'message_from_bytes'

Here is the script it fails in.

import imaplib, struct, time, email, Send_Email

#global sender

class Mail():
    def __init__(self):
        self.user= 'email address'
        self.password= 'password'
        self.M = imaplib.IMAP4_SSL('imap.gmail.com', '993')
        try:
            self.M.login(self.user, self.password)
        except:
            print("mail login failed")

    def checkMail(self):
        self.M.select()
        self.unRead = self.M.search(None, '(SUBJECT "Temp Monitor Command" UnSeen)')
        if len(self.unRead[1][0].split()) > 0:
            status, data = self.M.fetch(self.unRead[1][0], '(RFC822)')
            email_msg = email.message_from_bytes(data[0][1])
            if email_msg.is_multipart():
                for part in email_msg.walk():       
                    if part.get_content_type() == "text/plain":
                        body = part.get_payload(decode=True) 
                        body = body.decode()

                    elif part.get_content_type() == "text/html":
                        continue
            #print(self.M.fetch(self.unRead[1][0], "(BODY[HEADER.FIELDS (FROM)])"))
            return body
        else:
            return -1

Answer 1

I think the problem is nearby environment where you try to execute your code. Try to check installed modules in both cases. You can read here about How to list of used modules during execution. Also you should check which python instance used in both cases. To do this you can execute this

import sys 
print(sys.executable)
print(sys.version)