Execute command when port forwarding is successful

To print a message for instance or send a Matrix message thanks to matrix-commander.

ssh -NR 2224:localhost:22 benjamin@XXX.XXX.XXX.XXX echo 'Connection established'

hangs without output.

ssh -R 2224:localhost:22 benjamin@XXX.XXX.XXX.XXX echo 'Connection established'

Connection established

without hanging.

+12