APC PDU CLI automation over telnet

Question

I have seen numerous posts online about logging into an APC PDU over telnet using Python pexpect, PHP, etc. However, all of the examples are like this:

Python - telnet - automation APC PDU

https://github.com/quackenbush/APC

They log in using the Control Console, which I don't think offers as many metrics. I'm looking for a way to automate the command line interface and send various commands to check metrics.

I've learned this is possible by appending -c to your password at the login prompt (from this source: https://www.apc.com/us/en/faqs/FA156163/):

APC_DEFAULT_USER     = 'apc'
APC_DEFAULT_PASSWORD = 'apc -c'
self.child.expect('User Name : ')
self.child.send(APC_DEFAULT_USER + '\r\n')
self.child.expect('Password  : ')
self.child.send(APC_DEFAULT_PASSWORD + '\r\n')

But this is where I get stuck. I'd like a generic solution to allow me to specify different PDU commands as command line args like this:

--command power
--command current
etc.

I am using argparse to get the arguments from the user, so args.command looks like this:

parser.add_argument('--command', action='store', default='',
                    help='The command to run')

I also have no strong feelings about doing this in Python. I'm more than happy to use another language if it's more intuitive. I'm just trying to base my script on the quankenbush/APC script.

I've tried doing expects for the APC> prompt like this:

self.info("Attempting to run command: {}".format(self.command))
self.child.expect('APC> ')
self.sendnl(self.command)
self.child.expect(' OK')
self.child.expect('APC> ')

But I end up getting

"Command does not exist"

errors, even though I know the "power" and "current" commands do exist.

Here is the complete output (using --verbose mode):

$ python apc_metrics.py --host <my.ip.addr> --command power -v
Acquiring lock /tmp/apc.lock
Connecting to APC @ <my.ip.addr>
Logged in as user apc
Attempting to run command: power
apc    
******

American Power Conversion
Rack PDU AP7930 v3.7.3
AOS v3.7.3
Outlets: 24
(c) 2008 All Rights Reserved
Unit ID: RackPDU

 1: ON    : Outlet 1
 2: ON    : Outlet 2
 3: ON    : Outlet 3
 4: ON    : Outlet 4
 5: ON    : Outlet 5
 6: ON    : Outlet 6
 7: ON    : Outlet 7
 8: ON    : Outlet 8
 9: ON    : Outlet 9
10: ON    : Outlet 10
11: ON    : Outlet 11
12: ON    : Outlet 12
13: ON    : Outlet 13
14: ON    : Outlet 14
15: ON    : Outlet 15
16: ON    : Outlet 16
17: ON    : Outlet 17
18: ON    : Outlet 18
19: ON    : Outlet 19
20: ON    : Outlet 20
21: ON    : Outlet 21
22: ON    : Outlet 22
23: ON    : Outlet 23
24: ON    : Outlet 24

APC> 
power

DISCONNECTED from <my.ip.addr>
[
 E100 : Command does not exist
APC> 
4
 OK
 E100 : Command does not exist
APC> 


Bye.

Connection Closed - Bye
Connection closed by foreign host.
]

For completeness, my end goal is to run this script every minute or few minutes and write the data to a file to track power usage over time and eventually create some graph of this data.