Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Book Image

Linux Shell Scripting Cookbook, Second Edition - Second Edition

Overview of this book

The shell remains one of the most powerful tools on a computer system — yet a large number of users are unaware of how much one can accomplish with it. Using a combination of simple commands, we will see how to solve complex problems in day to day computer usage.Linux Shell Scripting Cookbook, Second Edition will take you through useful real-world recipes designed to make your daily life easy when working with the shell. The book shows the reader how to effectively use the shell to accomplish complex tasks with ease.The book discusses basics of using the shell, general commands and proceeds to show the reader how to use them to perform complex tasks with ease.Starting with the basics of the shell, we will learn simple commands with their usages allowing us to perform operations on files of different kind. The book then proceeds to explain text processing, web interaction and concludes with backups, monitoring and other sysadmin tasks.Linux Shell Scripting Cookbook, Second Edition serves as an excellent guide to solving day to day problems using the shell and few powerful commands together to create solutions.
Table of Contents (16 chapters)
Linux Shell Scripting Cookbook
Credits
About the Authors
About the Reviewers
www.PacktPub.com
Preface
Index

Temporary file naming and random numbers


While writing shell scripts, we often need to store temporary data. The most suitable location to store temporary data is /tmp (which will be cleaned out by the system on reboot). We can use two methods to generate standard filenames for temporary data.

How to do it...

Perform the following steps to create a temporary file and perform different naming operations on it:

  1. Create a temporary file as follows:

    $ filename=`mktemp`
    $ echo $filename
    /tmp/tmp.8xvhkjF5fH
    

    This will create a temporary file and print its filename which we store in $filename in this example.

  2. To create a temporary directory, use the following commands:

    $ dirname=`mktemp -d`
    $ echo $dirname
    tmp.NI8xzW7VRX
    

    This will create a temporary directory and print its filename which we store in $dirname in this example.

  3. To just generate a filename without actually creating a file or directory, use this:

    $ tmpfile=`mktemp -u`
    $ echo $tmpfile
    /tmp/tmp.RsGmilRpcT
    

    Here, the filename will be stored in...