Coproc in bash script

I'm trying to do a simple shell script that will make my raspberry's bluetooth discoverable but i'm facing some issues. My raspberry is running Raspbian. Running this through command line works perfectly: coproc bluetoothctl echo -e 'discoverable on' >&${COPROC} But when i create a shell script doing the following: #! /bin/bash coproc bluetoothctl echo -e 'discoverable on' >&${COPROC} with the command line "bash test_script.sh", the script is exectued correctly but the state of the bluetooth remains the same. Can someone give me a hand? Thanks!