Can't enable shell_history in rebar.config.

[sthames42]

rebar.config includes:

{shell, [
    {config, "./shell.config"},
    {apps, [...]}
]}.

shell.config includes:

[{kernel, [{shell_history, enabled}]}].

When I run rebar3 shell, shell history is not restored from the previous session.

This will work:

export ERL_AFLAGS="-config ./shell.config"
rebar3 shell

As long as I have the environment variable set, I can run the rebar3 shell command many times and the history is always restored.

Is this an issue with rebar3?

[ferd]

rebar3 shell is started after the node was already booted, such that the kernel is already configured and up by the time we even parse the config.

We cannot easily change these values, so this is one of the cases (along with various other node startup arguments) that cannot be covered by the configuration.

This is a known limitation for which we do not plan a workaround since it would involve major changes (either through incredible hacks to tear down and bring back up parts of kernel, or through architecture changes where rebar3 needs a thin wrapper that parses arguments and then execs into a new node) that are not likely to be worth it.

[sthames42]

Ok, thanks for clearing that up. Having not reviewed the rebar3 code, I was assuming it started erl with options appropriate to configure the environment (-pa, for example) and that a config file given in the shell options would be applied, as well. But after looking at how beam.swp is run, I can see the node is started as a "clean boot", loading only the kernel and stdlib applications. Features like shell_history are not available, therefore, because they must be enabled at startup.

While this means the rebar3 shell environment can, potentially, not be configured as the production environment, I understand why a change to allow kernel options is not planned. But could someone possibly update the docs to reflect this limitation and maybe offer the workaround with ERL_FLAGS? It would have saved me the hours I spent trying to determine why shell_history wasn't working.