Document possible values for --lang="LANG"

[jenlampton]

I am following the installation instructions for Civi and I'm stumped at how to build the command to install civi. I am a complete Civi Novice, but I think it will be exactly the right solutuon for one of my clients, so I really want to give it a try. The example provided is cv core:install --cms-base-url="URL" --lang="LANG" But there are things in here I don't know how to replace -- let's start with LANG.

I can tell this is language, and I can see that there are notes below stating that if I want to install a non-standard language, I need to have the language files downloaded, and the codes need to match. However, none of that is relevant for me, I want to install Civi in the default language.

What code do I put in here for the default language? Do I need to specify the code for US English, and if so, what would that be? Is it the lowercase und like it is in Drupal + Backdrop when the language is undefined? Or is there a constant to be used like LANGUAGE_NONE? Is it an ISO language code? (but fr_CA does not look like an ISO language code...) Is there a list of possible values? Is the example provided fr_CA the most commonly used language, and therefore probably US English? (My gut says no, this is probably French as used in Canada, but that doesn't help me determine what US English might be.)

My gut also said that maybe I should leave off the --lang="LANG" parameter entirely if I want to install Civi in the default language. But if that's the case, why would it be included in the "typical installation command" example?

(the above was my complete thought process while trying to install civi -- maybe not the best format for this ticket, but I wanted to write it all down while it's fresh in my mind.)

Things that might help me determine what to use for LANG:

• An example command of how to install Civi in US English (probably the most common use-case?)
• A complete list of allowed language values, including the default value
• An indication as to whether the --lang parameter is optional or required

Also, if there is documentation I should be consulting other than https://docs.civicrm.org/installation please let me know if I am looking in the wrong place :)