Book Image

Linux Essentials - Second Edition

By : Christine Bresnahan, Richard Blum
Book Image

Linux Essentials - Second Edition

By: Christine Bresnahan, Richard Blum

Overview of this book

Linux Essentials, Second Edition provides a solid foundation of knowledge for anyone considering a career in information technology, for anyone new to the Linux operating system, and for anyone who is preparing to sit for the Linux Essentials Exam. Through this engaging resource, you can access key information in a learning-by-doing style. Hands-on tutorials and end-of-chapter exercises and review questions lead you in both learning and applying new information—information that will help you achieve your goals! With the experience provided in this compelling reference, you can sit down for the Linux Essentials Exam with confidence. An open-source operating system, Linux is a UNIX-based platform that is freely updated by developers. The nature of its development means that Linux is a low-cost and secure alternative to other operating systems, and is used in many different IT environments. Passing the Linux Essentials Exam prepares you to apply your knowledge regarding this operating system within the workforce.
Table of Contents (19 chapters)

Using Loops

Conditional expressions are sometimes used in loops. Loops are structures that tell the script to perform the same task repeatedly until a particular condition is met (or until some condition is no longer met). For instance, Listing 11.5 shows a loop that plays all the .wav audio files in a directory.

The for loop as used here executes once for every item in the list generated by ls *.wav. Each of those items (filenames) is assigned in turn to the $d variable and so is passed to the aplay command.

The seq command can be useful in creating for loops (and in other ways too). This command generates a list of numbers starting from its first argument and continuing to its last one. For instance, typing...