How to keep tcp connection open?

[Peng Yu]

Hi,

{
    read -N 4 var
    n=${var%%:*}
    read -N "$((n-${#n}))" rest
    json=${var#*:}$rest
} < /dev/tcp/127.0.0.1/2828
echo "$json"
# echo will print '{"applicationType":"gecko","marionetteProtocol":3}'

I use the above code to get information from firefox marionette server
(it can be started with firefox --marionette command line option).

The above bash code has to be put in { } so that the connection to
/dev/tcp/127.0.0.1/2828 will not be reset.

For debugging purposes, I want to ensure the connection is not closed,
once I run a bash command even without {} (as interactive commands can
not be run in { }).

If I just run the following command in an interactive session,

read -N 4 var < /dev/tcp/127.0.0.1/2828

the next time when I run the following command, it will basically
establish a new connection to /dev/tcp/127.0.0.1/2828.

read -N "$((n-${#n}))" rest < /dev/tcp/127.0.0.1/2828

This is not what I want.

How can I solve this problem so that the connection to this tcp port
is not reset every time when I run an interactive bash command?

-- 
Regards,
Peng