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bashnetcat

Implementing netcat in bash

As the basis for a larger script I'm trying to write I'm trying to basically implement a basic netcat client in bash. My current script techincally works, it looks like this:

#!/bin/bash

exec 3<>/dev/tcp/$1/$2         

cat <&3 &                      
cat <&1 >3

The problem with it is that it leaves a hanging cat process which needs to be killed, but I can't figure an automatic way to do so, and manually running pkill cat doesn't really seem sporting.

Solution

  • It is a horrid kludge, but you could spawn a subshell and so something like this:

    CAT1_PID=$$
echo CAT1_PID > /tmp/CAT1_PID
exec cat <&3 &

    Then, of course, you run into race conditions if more than one copy of this script happens to be running.

    Depending on your shell, you may be able to call some form of exec and "rename" cat in the PS list. Then you can

    pkill the_cat_that_ate_the_network