Allow `-clean` command line option with `-app` and `-resource` options

[rjwills28]

We have a use case where we would want to launch a BOB screen in its own window from the terminal, e.g.

phoebus.sh -resource "file:/path/to/file/example.bob@target=window"

The only problem with this is that by default this will bring up the persisted Phoebus state, which might contain other open windows or screen editor tabs etc. At that point, the only way to ensure only the 'example.bob' screen appears is to make sure you close all the other windows/tabs before shutting phoebus down (not ideal!) or you first run with -clean:

phoebus.sh -clean
phoebus.sh -resource "file:/path/to/file/example.bob@target=window"

I feel like it would be much cleaner to be able to run something like:

phoebus.sh -clean -resource "file:/path/to/file/example.bob@target=window"

which is basically saying I want a clean start (no persisted state) and to open the following resource.

However the current design of Phoebus is such that -clean overrides any other option (e.g -resource xx, -app xx). Does anyone know the original reasoning behind this and whether we could change this behavior to something like that described above?

The desired behavior would be as such:

• If Phoebus isn't open then clean (i.e. do not load previous state) and open the resource/app.
• If Phoebus is already open, then the -clean is automatically ignored and the resource/app will just be opened as normal (and everything already open remains).

I am happy to put in a PR to make this change but wanted to get some feedback first to make sure I haven't missed anything about the behavior?

[shroffk]

I think this is not the ideal use of the -clean option

I would use the server optinon

get_free_port() {
    local port
    while true; do
        port=$(shuf -i 49152-65535 -n 1)
        ss -tuln | grep -q ":$port " || { echo $port; break; }
    done
}

RANDOM_PORT=$(get_free_port)

phoebus.sh -server ${RANDOM_PORT} -resource "file:/path/to/file/example.bob@target=window"

[shroffk]

The above will open a new instance of Phoebus, but I think it fits your usecase... you get a clean Phoebus instance and the resources option is used.
It is less expensive too... you don't have to clean out a lot of files.

[rjwills28]

I did just try that but it still loaded the persisted state? I think it still loads the ~/.phoebus/memento, which lists the previously open windows/tabs etc.

[shroffk]

Ok,
I will bring this up at the developers meeting to see how people are relying on the -clean behaviour

[rjwills28]

I think the conclusion to this was that firstly we needed somewhere to list/discuss suggested changes to the Phoebus launch mechanism so that facilities can give their input and we can check that these changes do not break anything. These changes could also be accompanied by a version bump. @shroffk - do we have a place where these issues could be raised and discussed?

I believe this change should have minimal impact on users though. The only users it will affect are those that are providing an argument with -clean that they expect to be ignored. For example phoebus.sh -clean -resource /xxx/xx/xx.bob. Originally this would just clean the environment and open nothing else, but with the new behavior the BOB screen will also be displayed. Changes required to the code are minimal (see example implementation: master...rjwills28:phoebus:change_launch_clean).