* A file: This is the most important item for Magwitch. He needs it to escape from his prison cell.
* Some food: Magwitch is hungry and wants food to sustain him while he is on the run.
* A drink: He wants a drink to quench his thirst.
* A few shillings: These are likely meant to help Magwitch purchase items he might need while escaping or to give to anyone helping him.
It's important to note that Magwitch never specifies *what* kind of food or drink he wants. He simply says, "bring something to eat and drink".
The convict's request for these specific objects highlights his desperate situation and his determination to escape.