Using Python to send commands to a subshell

Question

I need to send commands to shell "MYSHELL>" after it has been initiated.

prcs = subprocess.Popen("MYSHELL; cmnd1; cmnd2;",shell=True,
subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

outputPrcs, err =  prcs.communicate()
print outputPrcs

Problem only entering shell is implemented, Other commands (cmnd1; cmnd2;)aren't sent.

Result: MYSHELL>

Answer 1

From the docs :

communicate(self, input=None)
   Interact with process: Send data to stdin.  Read data from
   stdout and stderr, until end-of-file is reached.  Wait for
   process to terminate.  The optional input argument should be a
   string to be sent to the child process, or None, if no data
   should be sent to the child.

Notice, Wait for process to terminate. I think what you need is pexpect . It isn't in the standard library, but it'll do what you want.

Example:

import pexpect

process = pexpect.spawn("python")
process.expect_exact(">>> ")
process.sendline('print("It works")')
process.expect("\n.*\n")
response = process.after.strip()
print(response)

Output:

It works

Answer 2

If you want to send input to your shell then you should pass it as an argument in communicate , like so:

prcs = subprocess.Popen("MYSHELL",shell=True,
subprocess.PIPE, stdout=subprocess.PIPE, stderr=subprocess.PIPE)

outputPrcs, err =  prcs.communicate("cmnd1; cmnd2;")
print outputPrcs

test:

>>> from subprocess import *
>>> p = Popen("python", shell=True, stdin=PIPE, stdout=PIPE, stderr=PIPE)
>>> o,e = p.communicate("print 'it works'")
>>> print o
it works

>>> 

Answer 3

It will work @Ahmed. Try below code on linux:

from subprocess import *  
cmd = "MYSHELL\ncmd1\ncmd2\n"
p = Popen('/bin/bash', shell=False, universal_newlines=True, stdin=PIPE, stdout=PIPE, stderr=PIPE)    
o, e = p.communicate(cmd)    

print('Output: ' + o.decode('ascii'))  
print('Error: '  + e.decode('ascii'))  
print('code: ' + str(p.returncode))