An ssh public key in a ~/.ssh/authorized_keys file can have a command="" option which forces a particular command to be executed when the key is used to authenticate an ssh connection. This is a security control that mitigates against private key compromise. This is great when you only need to execute a single command. But if you need to perform multiple tasks, you would normally need to create and install a separate key pair for each command, or just not bother making use of forced commands and allow the key to be used to execute any command.