A lot of the time when I'm working on a project that uses memcached, I'll want to have a look at the data in the cache without using my application to make sure that it's doing what I expect. I didn't expect that wanting to list all keys on a memcached server was such a big request, but it looked like there wasn't any easy way to do it.
I did start a project named mempp to provide a CLI friendly interface to memcached via the Python bindings, but as it turns out you don't even need this. libmemcached ships with everything you need.
First, you'll need to install libmemcached-tools
sudo apt-get install libmemcached-tools
Then, if you want to list all keys stored on a server, you can use
$ memcdump --servers localhost:11211key_onekey_two_123
If you want to see the values of those keys, use
$ memccat --servers localhost:11211 key_oneFooBar
If you want to remove a key, use
$ memcrm --servers localhost:11211 key_one
With a combination of
memcrm you can poke around your memcached instance without needing to use telnet or list slabs or anything like that, which most posts advise you to do.