Is $env.NU_LIB_DIRS auto-populated?

[james-smith-za]

Reading the following lines:

nushell.github.io/book/configuration.md

Lines 393 to 395 in 787a5a1

	- `$env.XDG_DATA_HOME`: If this environment variable is set, Nushell sets the `$nu.data-dir` constant to this value. The `data-dir` is used in several startup tasks:
	- `($nu.data-dir)/completions` is added to the `$env.NU_LIB_DIRS` search path.

My initial understanding of this passage was that if $env.XDG_DATA_HOME is and ($nu.data-dir)/completions exists, then it gets added to $env.NU_LIB_DIRS automatically on nushell startup. However, looking around at what people report from their own configs, it appears that $env.NU_LIB_DIRS has to be built up somewhat manually. Indeed, in my own case, XDG_DATA_HOME is set and the completions dir exists, but if I don't manually build $env.NU_LIB_DIRS, then it's just empty.

Have I misunderstood something here? Happy to contribute a PR with a doc update to clarify, if someone is willing to help me understand what the correct behaviour is.

[ysthakur]

Are you setting $env.NU_LIB_DIRS in env.nu? If you set it in config.nu instead, I don't think $nu.data-dir will be set to what you want.

Stuff inside $env.NU_LIB_DIRS is available for you to source/use/overlay use, but it's not automatically loaded. So even if the directory inside which your completions are is added to $env.NU_LIB_DIRS, you'll still have to source/use those completions.

Also, I'd recommend using the const variable $NU_LIB_DIRS. You'll have to set it in config.nu (can't set it in env.nu). The benefit of this is that you can set it config.nu and immediately take advantage of it in config.nu.

[james-smith-za]

Are you setting $env.NU_LIB_DIRS in env.nu? If you set it in config.nu instead, I don't think $nu.data-dir will be set to what you want.

I am not setting $env.NU_LIB_DIRS anywhere.

I have this (among other things) in env.nu:

$env.XDG_DATA_HOME = ($env.HOME | path join ".local/share")

So firing up a new instance of nushell gives me the following:

~> echo $nu.data-dir
/home/james/.local/share/nushell

So this is in line with what I expect based on the linked docs: "Nushell sets the $nu.data-dir constant to this value."

However,

~> echo $env.NU_LIB_DIRS
╭────────────╮
│ empty list │
╰────────────╯

Stuff inside $env.NU_LIB_DIRS is available for you to source/use/overlay use, but it's not automatically loaded. So even if the directory inside which your completions are is added to $env.NU_LIB_DIRS, you'll still have to source/use those completions.

Thanks for mentioning - I did manage to figure this part out after posting. It's actually getting $env.NU_LIB_DIRS populated that's puzzling me. I have adjusted the issue title to reflect my actual query.

Also, I'd recommend using the const variable $NU_LIB_DIRS. You'll have to set it in config.nu (can't set it in env.nu). The benefit of this is that you can set it config.nu and immediately take advantage of it in config.nu.

I didn't think to look at the const version but after you mention this, lo and behold:

~> echo $NU_LIB_DIRS
╭───┬──────────────────────────────────────────────╮
│ 0 │ /home/james/.config/nushell/scripts          │
│ 1 │ /home/james/.local/share/nushell/completions │
╰───┴──────────────────────────────────────────────╯

Again, I'm not setting $NU_LIB_DIRS anywhere. The directory /home/james/.local/share/nushell/completions gets appended here. I'd expected this to be in $env.NU_LIB_DIRS instead based on the docs.

I suppose from a practical point of view everything is now fine, I can use my completion files and carry on about my day, but I would like to understand what is actually happening - am I doing the right thing or am I holding it wrong?

As mentioned - also willing to contribute by helping make the docs a bit clearer once things actually click in my own head.

[james-smith-za]

Just a follow-on, trying to understand what is actually going on here:

https://github.com/nushell/nushell/blob/419ceed8d506a2d8bf8e2e687385ad3fd9ace495/src/main.rs#L166-L186

This code seems to suggest that the behaviour I am seeing is expected: $NU_LIB_DIRS gets populated based on whether the env variable is set (above, on line 158 if I dig into the logic) and $env.NU_LIB_DIRS is set to empty?

Is the comment marking $env.NU_LIB_DIRS as deprecated correct? If so, I will adjust the wording in the docs that I linked in the opening comment on this issue and submit a PR later today. I am also happy to adjust the entry at https://www.nushell.sh/book/special_variables.html#env-nu-lib-dirs to indicate that users should rather use the const version.

[ysthakur]

I am not setting $env.NU_LIB_DIRS anywhere.

Sorry, I meant to ask if you were setting the xdg variable in your env.nu (which you are)

Just looked at that code you linked, looks like you're right that the constant is supposed to be set and the environment variable is supposed to be empty.

Yes, it'd be great if you could open a PR to update the docs to mention that the constant is what's updated when you set the xdg var, and to emphasize more clearly that $env.nulibdirs is deprecated and set to an empty list. Appreciate you being open to contributing