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)

Managing log files with logrotate

Log files keep track of events on the system. They are essential for debugging problems and monitoring live machines. Log files grow as time passes and more events are recorded. Since the older data is less useful than the current data, log files are renamed when they reach a size limit and the oldest files are deleted.

Getting ready

The logrotate command can restrict the size of the log file. The system logger facility appends information to the end of a log file without deleting earlier data. Thus a log file will grow larger over time. The logrotate command scans log files defined in the configuration file. It will keep the last 100 kilobytes (for example, specified SIZE = 100 k) from the log file and move the rest of the data...