Usage of nc with timeouts in ms

Question

I'm using nc in a Debian environment:

# dpkg -l | grep netcat
ii  netcat-traditional                    1.10-41+b1
# cat /etc/debian_version
9.4

Its help page describe the behavior of the -w flag:

-w secs                 timeout for connects and final net reads

So it seems it's accept seconds only (as integer). I need to reduce this timeout because I have to poll a remote device twice per second:

echo -n read_input | nc -w 1 192.168.1.185 8800

this command is sent by an application. I can only set the console command to be executed.

Of course, with a timeout of 1 second I can barely poll the device about 1 time every two seconds (to avoid to open a new socket when the previous is not closed yet).

Do you confirm there's no way to achieve this? So, is there a way to have a timeout < 1 second with netcat? For my own curiosity: why a network timeout should be in seconds?

Answer 1

I don't think it is possible with nc alone. But you can additionally use the timeout tool (GNU coreutils package) which allows you to run a command with a timelimit specified as a floating point number, e.g. like so.

echo -n read_input | timeout 0.5 nc 192.168.1.185 8800