Play with WordPress languages in cli.

wp-cli-languages.sh

#!/bin/bash

# Note the fifference between Install and Update
# Install : if the language doesn't exist, this is the first step to get the last asked language package. It is also needed, in order to update.
# Update : will get the last asked translation package, only if the language is already installed. 

# Install core in french if not existing 
wp language core install fr_FR

# Update all existing core languages 
wp language core update

# Install a theme language if not existing
wp language theme install twentyseventeen fr_FR

# Update all themes languages
wp language theme update --all

# Install for all plugins, the french language
wp language plugin install fr_FR --all

# Update for all plugins, the french language
wp language plugin update --all

# In a multisite, install and update all languages for plugins and core
# @see https://gist.github.com/MaximeCulea/575e493a061359edbb12cefc3aa4c770#file-wp-cli-ms-cheatset-php-L43

# For doing a more complex demand, as downloading all the languages
https://gist.github.com/johnbillion/5f6c6395f660282ddb5814f4fb62c8fe