WriteTarget is a template based text generator.
It is simple and easy to use, see below for "Hello World" example. It does not define its own language, as M4 or Autogen do, it is not sophisticated nor complicated. It rather demonstrates power of classic well-known shell language, exploiting its not so known possibilities. The Bash programming language has all the capabilities which are necessery to generate text from templates - string expansion, variables, functions and so on.
WriteTarget just makes this a bit easier, defining several elagant functions. If you are new to Bash, you may want to read some tutorial, as this one, but standard Bash manual is also good starting point. It is rather short (as for programming language manual), and worth reading. Just type man bash in your console. If you have no man command, do not panic, type man bash in Google. The WriteTarget is just a simple way to turn your favourite interpreter into templatized blog engine, wiki-like CMS, C++ or Java code generator or - simply - macro preprocessor.
One can use WriteTarget for HTML generating, for C-code programming and for any text populating. There are two essential functions in WriteTarget: target - defining text destination, the point in template where the text will be inserted - and write - writing the text at this point.