Question regarding Paramiko and SSH channel

Forgive me, I know nothing about network programming.

I have a group of servers I need to perform maintenance on. Sudo is not permitted. As such, I have to use "su -" to elevate to root and then carry out a list of tasks as root and grab the results from each command so I can view the logs later. I have a script currently working, but it feels hackish and I am thinking there must be a better way to do what I'm doing.

ssh = paramiko.SSHClient()    
ssh.set_missing_host_key_policy(paramiko.AutoAddPolicy())
ssh.connect(<my connection details>)    
channel = ssh.invoke_shell()    
try:    
    channel.send("su -\n")    
    while not channel.recv_ready():    
        print "Waiting for root challenge..."    
        time.sleep(2)    
    results += channel.recv(1024)  
    channel.send("%s\n" % rootpass)    
    while not channel.recv_ready():    
        print "Authenticating..."    
        time.sleep(2)
    results += channel.recv(1024)  
    channel.send("yum update <rpm>\n")    
    while not channel.recv_ready():
        print "Working on yum update..."
        time.sleep(10)
    results += channel.recv(1024)
except Exception, e:
    print e

return results

1) The time.sleep's feel hackish. Some of the commands, like a "yum update" return a lot of text and so I put a longer time interval on the recv_ready() check, because I wo开发者_Go百科uld prefer not to receive a partial result.

2) I do not understand blocking vs non-blocking. I think channels in Paramiko are by default in blocking mode, meaning (I think) there may be a better way to wait until the command finishes and to get the finished results, rather than putting sleeps in there?