Core session hangs when both FRR and Quagga present

[FamousPond]

Describe the bug
When both FRR and Quagga are present on the hosts system booting the FRR zebra causes the session to hang.

To Reproduce
Steps to reproduce the behavior:

1. Ensure that both frr and quagga are installed.
2. Check /opt/core/etc/core.conf to ensure that the path to the frr version of zebra, ospf and ospfv6 is first in the list. This likely entails changing the core.conf with the following lines:

frr_bin_search = "/usr/lib/frr /usr/bin /usr/local/bin"
frr_sbin_search = "/usr/lib/frr /usr/local/sbin /usr/sbin /usr/libexec/frr"

4. load or create a core scenario with nodes running frr zebra.
5. Try to start the scenario and you will see that it will not load and that is is waiting on the command: bash frrboot.sh zebra

Desktop (please complete the following information):

• OS: Ubuntu 22.04.05 LTS
• CORE Version: 9.2.0
• EMANE Version: 1.5.1

Additional context
Using the vcmd command to debug I can see that the frr zebra does load and work.

It seems that the problem occurs in core/daemon/utils.py in the function cmd() on line 224. When p.communicate() is run.
For some reason stdout and stderr are never returned which causes the program to hang waiting for the response. Interestingly a return code is returned if p.wait() is used instead of p.communicate().

[bharnden]

The latest FRR does not work and those services have not been updated with it. You have to use a version prior to 9 or create new services.

[FamousPond]

In what way do they not work? In my testing frr works on the node but hangs in the loading process.

[bharnden]

Newer versions of FRR from my understanding and other users reporting have changed binary names etc. I don't use FRR, so I don't have any personal experience. The services were contributed, quite some time ago.

[FamousPond]

In my experience using the latest version of FRR in Core 9.2.0 works perfectly fine when Core is install with inv install --no-ospf. When Core is installed with inv install or via the package, both FRR and Quagga work and can be used in the same network, but the core sessions hangs whilst loading the frr zebra. (I hacked together a way to bypass the problem).