Book Image

Linux Shell Scripting Cookbook - Third Edition

By : Clif Flynt, Sarath Lakshman, Shantanu Tushar
Book Image

Linux Shell Scripting Cookbook - Third Edition

By: Clif Flynt, Sarath Lakshman, Shantanu Tushar

Overview of this book

The shell is the most powerful tool your computer provides. Despite having it at their fingertips, many users are unaware of how much the shell can accomplish. Using the shell, you can generate databases and web pages from sets of files, automate monotonous admin tasks such as system backups, monitor your system's health and activity, identify network bottlenecks and system resource hogs, and more. This book will show you how to do all this and much more. This book, now in its third edition, describes the exciting new features in the newest Linux distributions to help you accomplish more than you imagine. It shows how to use simple commands to automate complex tasks, automate web interactions, download videos, set up containers and cloud servers, and even get free SSL certificates. Starting with the basics of the shell, you will learn simple commands and how to apply them to real-world issues. From there, you'll learn text processing, web interactions, network and system monitoring, and system tuning. Software engineers will learn how to examine system applications, how to use modern software management tools such as git and fossil for their own work, and how to submit patches to open-source projects. Finally, you'll learn how to set up Linux Containers and Virtual machines and even run your own Cloud server with a free SSL Certificate from letsencrypt.org.
Table of Contents (14 chapters)

Playing with xargs

Unix commands accept data either from the standard input (stdin) or as command line arguments. Previous examples have shown how to pass data from one application's standard output to another's standard input with a pipe.

We can invoke applications that accept command-line arguments in other ways. The simplest is to use the back-tic symbol to run a command and use its output as a command line:

$ gcc `find '*.c'`

This solution works fine in many situations, but if there are a lot of files to be processed, you'll see the dreaded Argument list too long error message. The xargs program solves this problem.

The xargs command reads a list of arguments from stdin and executes a command using these arguments in the command line. The xargs command can also convert any one-line or multiple-line text inputs into other formats, such as multiple lines (specified number of columns)...