L10nPackBuilder is a project mainly written in Shell, it's free.
TYPO3 Language Pack Builder
This script is used by the Pootle based translation server for the TYPO3 project to build language pack.
Tools to convert LLXML file to XLIFF
llxml2xliff extensionKey en sourceFile
llxml2xliff extensionKey languageKey sourceFile targetFile
Tools to convert XLIFF to LLXML
xliff2llxml extensionKey default xliffFile
xliff2llxml extensionKey languageKey xliffFile