Insert commands to a screened session.

screen.sh

# Create a screened bash instance.
screen -S term01 bash

# Open a new terminal window and send the command 'ls\n' - the newline runs the command.
screen -S term01 -p 0 -X stuff "ls\n"

# -S <name> is the screen name
# -p 0 - tells it to use the first window, there can be more than one. (Default one)
# -X stuff '<cmd>' - Send the specified command to a running screen session.