Module Release November 2001: Processing Text Streams Using Filters

The first certification-oriented module release starts from what is arguably the fundamental nature of Unix, i.e. the way its component-based architecture enables a user to program just about any function that is within their own intellectual capacity.

A critical feature which makes Unix so programmable is its use of ASCII-based data streams for inter-process communication. Because every Unix tool can send to, receive from, and process the data streams of every other tool, any number of these utilities can be combined together to complete a specialist task; no matter how unique that task may be. This means that the vast majority of routine or computationally difficult tasks can be automated and/or managed remotely without direct human intervention.

It also means that a fully functional Unix system can be very ‘mean and lean’. There is no need to permanently combine massive amounts of functionality in a single bloated program. Tiny, single function, utilities can merely be brought together on a just-in-time basis to accomplish each a task only when it becomes necessary.

This month's module release covers an selection of the tools which can be used to manipulate and filter Unix text data streams as they pass from one utility to another. They include: cut, expand, fmt, head, join, nl, od, paste, pr, split, tac, tail, tr, wc, xargs, sed.

On completion of a Linux course based on this module, a student should be able to use and combine these tools to filter data streams passing between files and processes or between running processes. In addition to teaching basic text manipulation skills, knowledge of these particular utilities will provide a firm foundation from which to develop more sophisticated Linux system administration and programming techniques.

This month's module release covers an selection of the tools which can be used to manipulate and filter Unix text data streams as the pass from one utility to another. They include: cut, expand, fmt, head, join, nl, od, paste, pr, split, tac, tail, tr, wc, xargs, sed.

On completion of a Linux course based on this module, a student should be able to use and combine these tools to filter data streams passing between files and processes or between running processes. In addition to teaching basic text manipulation skills, knowledge of these particular utilities will provide a firm foundation from which to develop more sophisticated Linux system administration and programming techniques.