Efficiently test if a port is open on Linux

Question

Can anyone tell me how to efficiently check if a port 445 is open/listening on a server with bash script?

Answer 1

Below is the code to test for listening on a local server in a script:

exec 6<>/dev/tcp/127.0.0.1/445 || echo "No one is listening!"

exec 6>&- # close output connection

exec 6<&- # close input connection

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