I have two languages:
- french
- arabic
I want to completely translate the arabic interface. If there a way to export the englisch translations, add the arabic one and reimport the file?
It can be done using Translation template extractor module
If you are a translator, install the module on a Drupal site as you would with any other module. Once potx module is turned on, you can go to the "Extract strings" tab on the Locale administration interface, select the module or theme you want to have a translation template for, and submit the form. You will get one single template file generated.
I didn't get you! You need to completely translate the Arabic interface? Add the Arabic language to your website then simply, download it's translation file and import it into admin/config/regional/translate/import
. What is the problem?
Completely translating the Drupal "interface" in another language is a bit bizarre/strange (as confirmed also by some of the other answers already). Therefor it may help to correctly understand the various Drupal components related to 'translation', as further explained below.
Drupal's translation system consists of 2 basic components: the translation of the interface and the translation of the content of a site.
The translation of the interface is about the translation of various text strings used throughout the site, like labels used on buttons such as submit, or on tabs such as view or edit. They are the same on all sites (no matter what actual content is contained in a site).
The translation of the content is about the translation of nodes and entities. It requires a place to actually store the translated versions of the content (in multiple languages) and a system to choose which content is to be displayed where. The systems available for translation of content are:
Typical (often used) modules related to translations:
Modules to actually manage translations of nodes and/or entities: