Python3 error: invalid mode %r" % mode, trying to use object in os.popen

Question

I am trying to access data from an object that has just unpickled and use that with

os.popen()

hitting error

Traceback (most recent call last):

  File "tmpclient4.py", line 46, in <module>

    stream = os.popen('%t.cmd', '%t.arg')

  File "/usr/lib/python3.8/os.py", line 978, in popen

    raise ValueError("invalid mode %r" % mode)

ValueError: invalid mode '%t.arg'

or error:

ValueError: invalid mode 'htop' #my object value

using

stream = os.popen('%t.cmd', '%t.arg')

or

stream = os.popen(t.cmd, t.arg)

code:

import socket

import pickle

import os

HEADERSIZE = 10

s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)

s.connect(('192.168.42.14', 666))

class Zeroquery:

        # Initializer / Instance Attributes

        def __init__(self, cmd, arg):

                self.cmd = cmd

                self.arg = arg

while True:

        full_msg = b''

        new_msg = True

        while True:

                msg = s.recv(16)

                if new_msg:

                        print("new msg len:",msg[:HEADERSIZE])

                        msglen = int(msg[:HEADERSIZE])

                        new_msg = False

                print(f"full message length: {msglen}")

                full_msg += msg

                print(len(full_msg))

                if len(full_msg)-HEADERSIZE == msglen:

                        print("full msg recvd")

                        t = pickle.loads(full_msg[HEADERSIZE:])

                        print(t.cmd, t.arg)

                        if t.cmd:

                                stream = os.popen(t.cmd, t.arg)

                                output = stream.read()

                                print(output)

                        new_msg = True

                        full_msg = b""

My question is how do I use os.popen using my object data?

Answer 1

You need to create a string with command and argument

cmd = "{} {}".format(t.cmd, t.arg)

or you can use f-string

cmd = f"{t.cmd} {t.arg}"

or if cmd and arg are strings

cmd = " ".join([t.cmd, t.arg])

cmd = t.cmd + " " + t.arg

then use it as the first argument

os.popen(cmd) 

By the way, you can also create method __str__ in Zeroquery

class Zeroquery:

    # Initializer / Instance Attributes

    def __init__(self, cmd, arg):

        self.cmd = cmd

        self.arg = arg

    def __str__(self):

        return self.cmd + " " + self.arg

and then you can use str(t)

os.popen( str(t) )

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