bash - Send command to a background process

Question

I have a previously running process (process1.sh) that is running in the background with a PID of 1111 (or some other arbitrary number). How could I send something like command option1 option2 to that process with a PID of 1111?

I don't want to start a new process1.sh!

Answer 1

Named Pipes are your friend. See the article Linux Journal: Using Named Pipes (FIFOs) with Bash.