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

Answer 1

You can use the bash's coproc comamnd. (avaliable only in 4.0+) - it's like ksh's |&

check this for examples http://wiki.bash-hackers.org/syntax/keywords/coproc