from scratch moreoverwe'll find that python not only includes all the interfaces we need in order to write system toolsbut it also fosters script portability by employing python' standard librarymost system scripts written in python are automatically portable to all major platforms for instanceyou can usually run in linux python directory-processing script written in windows without changing its source code at all--simply copy over the source code though writing scripts that achieve such portability utopia requires some extra effort and practiceif used wellpython could be the only system scripting tool you need to use the next five to make this part of the book easier to studyi have broken it down into five in this 'll introduce the main system-related modules in overview fashion we'll meet some of the most commonly used system tools here for the first time in we continue exploring the basic system interfaces by studying their role in core system programming conceptsstreamscommand-line argumentsenvironment variablesand so on focuses on the tools python provides for processing filesdirectoriesand directory trees in we'll move on to cover python' standard tools for parallel processing--processesthreadsqueuespipessignalsand more wraps up by presenting collection of complete system-oriented programs the examples here are larger and more realisticand they use the tools introduced in the prior four to perform realpractical tasks this collection includes both general system scriptsas well as scripts for processing directories of files especially in the examples at the end of this partwe will be concerned as much with system interfaces as with general python development concepts we'll see nonobject-oriented and object-oriented versions of some examples along the wayfor instanceto help illustrate the benefits of thinking in more strategic ways "batteries includedthis and those that followdeal with both the python language and its standard library-- collection of precoded modules written in python and that are automatically installed with the python interpreter although python itself provides an easy-touse scripting languagemuch of the real action in python development involves this vast library of programming tools ( few hundred modules at last countthat ship with the python package system tools