Mnemonic passwords generally stink. A random sequence of letters, digits and punctuation is more secure—just don't write down your passwords, like the knucklehead antagonist does in Ready Player One!
In the password generating tool from my last
at its most simple, you specify the number of characters you want in the
password, and each is then chosen randomly from a pool of acceptable values.
With the built-in
RANDOM in the Linux shell, that's super easy to do: