Removing the tc config on a particular interface
I am new to using the tc command.
I am writing a test script to add delays to an interface. This is being done using python and fabric api
So the script will do something like:
sudo tc qdisc add dev eth1 root netem delay
And at the end of script we would do
sudo tc qdisc del dev eth1 root netem
But at the same time I wanted to make sure at the very beginning that there was no existing tc control that has been done on the system. So I wanted to run the delete command before the whole script started. but that gives me an error if there is no tc config done.
abc@abcvmm:~$ sudo tc qdisc del dev eth1 root netem
RTNETLINK answers: Invalid argument
Is there a way to delete the interface configured only if there is an existing tc config done and not otherwise.
Answer
your first step would be: tc qdisc del dev eth1 root
and then: tc qdisc add dev eth1 root handle 1: htb default 100
Checkout my code in my git repo: https://github.com/Puneeth-n/tcp-eval/blob/development/topology/build_net.py
I think I have implemented already what you are trying to implement (using fabric). Or may be you can use parts of the code.
The code makes sure that if there is no error when you are trying to delete a non existing qdisc.