Shell class in Python executes a single /bin/bash subprocess and gives to it commands writing on stdin. Needs improovment

shell.py

#Hi this class spawns a single subprocess /bin/bash and pass commands to it's stdin, this means that you can also
#execute cd commands here is an example that prints the /etc/passwd file and then echoes "Done"
#the class is only a proof of concept and has to be improoved
#for example the get_beffered_output() could not give the entire output of the command we executed depending on how much time the
#command uses to end

import subprocess
import threading
import time

class Shell:
	def __init__(self):
		self.process = subprocess.Popen(["/bin/bash"], stdout = subprocess.PIPE, stdin = subprocess.PIPE)
		self.reader_thread = threading.Thread(target = self.read)
		self.buffer = []
		self.running = True
		self.reader_thread.start()	

	def execute(self, command):
		self.process.stdin.write(command.strip("\n") + "\n")

	def get_buffered_output(self):	
		time.sleep(2)
		buffer = self.buffer
		self.buffer = []
		return "".join(buffer)

	def read(self):
		while self.running:
			line = self.process.stdout.readline()
			self.buffer.append(line)
			
	
	def close(self):
		self.running = False
		self.execute("exit")

shell = Shell()
shell.execute("cd /")
shell.execute("cd etc")
shell.execute("cat passwd")
shell.execute("echo Done")
print shell.get_buffered_output()
shell.close()