Error in the output of some commands with subprocess PIPE Popen

I'm doing a server client with sockets, and I'd like to run a command from the client to the server (where it runs), save the output, and then send it (python 2.7.15)

Server Code:

#!/usr/bin/env python
#-*- coding:utf-8 -*-
#Se importa el módulo
import socket, os, getpass, shutil
from subprocess import PIPE, Popen
name_host_server = getpass.getuser()
carpeta_actual_server = os.getcwd()
#instanciamos un objeto para trabajar con el socket
ser = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
server = ""
port = 8000
#Puerto y servidor que debe escuchar
ser.bind((server, port))
ser.listen(1)
#Instanciamos un objeto cli (socket cliente) para recibir datos
cli, addr = ser.accept() 
while True:

recibido = cli.recv(1024)
if recibido=="close":
    break
comando = recibido.split(" ", 1)
proceso = Popen(comando, stdout=PIPE, stderr=PIPE)
resultado = proceso.stdout.read()
error_resultado = proceso.stderr.read()
if resultado:
    cli.send(resultado)
elif error_resultado:
    cli.send(error_resultado)
proceso.stdout.close()
if ser == True:
print("Conexion cerrada")
#Cerramos la instancia del socket cliente y servidor
cli.close()
ser.close()

I've been reporting and it can be done with the subprocess module, it's easy to understand, but it does not work at all well.

Here's the problem:

while True:
   recibido = cli.recv(1024)
   if recibido=="close":
       break
   comando = recibido.split(" ", 1)
   proceso = Popen(comando, stdout=PIPE, stderr=PIPE)
   resultado = proceso.stdout.read()
   error_resultado = proceso.stderr.read()
   if resultado:
      cli.send(resultado)
   elif error_resultado:
      cli.send(error_resultado)
   proceso.stdout.close()

What I do is a variable comando that catches me the text string that I put, and separates it into a list with split() , separates it in the first space there is. Then I do the variable proceso where I execute the command, and I capture what is in the pipes stdout=PIPE and stderr=PIPE .

I read the output of the command in the variable resultado and the error output in error_resultado , to do an if by which I say that if the resultado or resultado_error comes out, send me the output to the customer.

All that goes well, but there are commands that do not quite go like cd shred -u , rm -r , when I insert these commands, I get to see the argument --help , since it gives error , which I do not understand.

The thing is that I do not understand its logic, since at the beginning of everything I do is convert the string into a list. that is, I do this:

>>> comando = "shred -u"
>>> resultado = comando.split(" ",1)
>>> print(resultado)
['shred', '-u']

Thing that should work because the subprocess module accepts the list (theoretically).