bluetooth – / dev / rfcomm busy device

sorry for my English

I've tried sending the command (echo 'h'> / dev / rfcomm0) from the Ubuntu terminal to my Arduino using Bluetooth hc-06. but he tells me rfcomm0 busy device.

my pc connects well to bluetooth, i use blueman, i have an arduino

the serial port of my arduino also tells me the same message when I try to open it (device / dev / rfvomm busy)

Thank you for your cooperation, I remain attentive