The goi18n command formats and merges translation files.
go get -u github.com/nicksnyder/go-i18n/goi18n goi18n -help
goi18n formats and merges translation files. Usage: goi18n [options] [files...] Translation files: A translation file contains the strings and translations for a single language. Translation file names must have a suffix of a supported format (e.g. .json) and contain a valid language tag as defined by RFC 5646 (e.g. en-us, fr, zh-hant, etc.). For each language represented by at least one input translation file, goi18n will produce 2 output files: xx-yy.all.format This file contains all strings for the language (translated and untranslated). Use this file when loading strings at runtime. xx-yy.untranslated.format This file contains the strings that have not been translated for this language. The translations for the strings in this file will be extracted from the source language. After they are translated, merge them back into xx-yy.all.format using goi18n. Merging: goi18n will merge multiple translation files for the same language. Duplicate translations will be merged into the existing translation. Non-empty fields in the duplicate translation will overwrite those fields in the existing translation. Empty fields in the duplicate translation are ignored. Adding a new language: To produce translation files for a new language, create an empty translation file with the appropriate name and pass it in to goi18n. Options: -sourceLanguage tag goi18n uses the strings from this language to seed the translations for other languages. Default: en-us -outdir directory goi18n writes the output translation files to this directory. Default: . -format format goi18n encodes the output translation files in this format. Supported formats: json, yaml Default: json