Use socat to spawn interactive binaries
Did you ever wondered what you can do if you can run an interactive binary on a server which can be exposed via tcp to any user in the world? As soon as a user initiates the tcp connection, you spin up an instance of the binary, send output over the network and wait for input over the network.
This type of deployement is often used in CTF competitions to allow the participants to hack a binary remotely.
Following socat command runs a python file every time a tcp-connection is made to the listening port.
socat tcp-listen:8888,reuseaddr,fork exec:'python pkcs7.py'