code hangs when running interactive shell using paramiko

Question

I have written below code to run 3 command in remote server interactively

But when I checked 3rd command never executed and code stuck here is my code

def execute():
    ssh = paramiko.SSHClient()
    ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
    ssh.connect('ipaddress', username='user', password='pw')

    chan = ssh.invoke_shell()  # start the shell before sending commands

    chan.send('cd /path to folder/test')
    chan.send('\n')
    time.sleep(3)
    chan.send("ls -l")
    chan.send('\n')
    buff = ''
    while not buff.endswith("test >"):
        resp = chan.recv(9999)
        # code stuck here after 'path to folder/test >' comes in shell prompt
        buff += resp
        print resp

    print "test"
    chan.send("ls -lh")
    chan.send('\n')
    time.sleep(5)
    buff = ''
    while not buff.endswith("test >"):
        resp = chan.recv(9999)
        buff += resp
        print resp

if __name__ == "__main__":
    execute()

When I ran I got output of ls -l but ls -lh never executed my code stuck in first while loop. Anyone please help to resolve my issue

Answer 1

The code has following 2 errors:

• The call to channel.recv is blocking, you should first check if channel has any data to be read or not using channel.recv_ready()

• Also don't use buff.endswith("test >") as a condition.As the file_name might not always be at the last in buff.

Change the while block to following and it will run the way you want

    while "test >" not in buff:
        if chan.recv_ready():
            resp = chan.recv(9999)    
            # code won't stuck here
            buff+=resp
            print resp