Linux Utilities Cookbook

Linux Utilities Cookbook

By : James Kent Lewis

Buy this Book

Linux Utilities Cookbook

By: James Kent Lewis

Buy this Book

Overview of this book

Linux is a stable, reliable and extremely powerful operating system. It has been around for many years, however, most people still don't know what it can do and the ways it is superior to other operating systems. Many people want to get started with Linux for greater control and security, but getting started can be time consuming and complicated. A practical, hands-on guide that provides you with a number of clear step-by-step examples to help you solve many of the questions that crop up when using an operating system you may not be familiar with. Presenting solutions to the most common Linux problems in a clear and concise way, this helpful guide starts with spicing up the terminal sessions by command retrieval and line editing, and shell prompt variables. We will then get to know the different desktops (GUIs) available for Linux systems and which is the best fit for you. We will then explore the world of managing files and directories, connectivity, and what to do when it goes wrong. We will also learn a range of skills, from creating and managing user accounts to securing your system, managing and limiting processes, and letting information flow from one process to another using pipes. Later, we will master disk management, working with scripts and automating tasks quickly, and finally, understand the need for a custom kernel and tips on how to build one. Based on the author's extensive experience, there is a section on best practices that every Linux user should be familiar with.

Linux Utilities Cookbook

Credits

About the Author

About the Reviewers

www.PacktPub.com

Preface

Free Chapter

Using the Terminal / Command Line

Introduction

Command retrieval and line editing

Using history

Filename auto-completion

The shell prompt

Other environment variables

Using aliases

The .bashrc file

Dealing with blanks and special characters in filenames

Understanding the $? variable

Redirection and piping

Sending output from one terminal to another

Using the Screen program

The Desktop

Introduction

GNOME 2

KDE desktop

xfce

LXDE

Unity

Mate

Files and Directories

Introduction

Copying, removing, and updating files and directories

Finding files using find and locate

Creating text files – vim, Emacs, and others

Using the file command

Using grep to find patterns

Compressing files using ZIP and TAR

Other helpful commands such as stat, sum, touch, and more

Networking and the Internet

Introduction

Troubleshooting bad connections

Copying files to another machine – FTP and SCP

Logging into another machine – Telnet and Secure Shell

Getting a web page without a browser – wget

Browsing the web – Firefox

E-mail – Using a web mail program

Running your own web server – httpd

What is using that port? The /etc/services file

IPv4 versus IPv6

Permissions, Access, and Security

Introduction

Creating and managing user accounts – useradd

Working with passwords

Working with file permissions

Working with the firewalls and router settings

Working with Secure Linux – SELinux

Using sudo to secure a system

The /tmp directory

Processes

Introduction

Understanding processes

Examining processes with ps

Examining processes using top

Changing priorities with nice

Observing a process using the /proc filesystem

Disks and Partitioning

Introduction

Using fdisk

Using mkfs to format a drive

Using fsck to check the filesystem

Logical Volume Management (LVM)

Working with Scripts

Introduction

Removing text from a file

Using script parameters

Coding a loop in a script

Backing up your system

Locking a file for only one use at a time

Getting introduced to Perl

Automating Tasks Using Cron

Introduction

Creating and running a crontab file

Running a command every other week

Reporting the errors from a crontab file

The Kernel

Introduction

A brief look at module commands

Building a kernel from kernel.org

Using xconfig to modify the configuration

Working with GRUB

Understanding GRUB 2

Linux Best Practices

Introduction

Root user versus normal user

Running the GUI

Creating, verifying, and storing backups

Permissions and who you are

Making backups in real time

Environment variables and shells

The best environment

Using and monitoring a UPS

Being careful when copying files

Verifying archive files and using checksums

Firewalls, router settings, and security

What to do if you find an intrusion

Spaces in filenames

Using scripts and aliases to save time and effort

Using scp and ssh with automatic authentication

Saving history and taking screenshots

Space on drives

Being open to new ideas

Finding Help

Introduction

Using man pages

Using the info command

Commands and the Usage section

Local documentation directories

Browsing the web to find help

Distribution release notes

Linux users' groups

Internet Relay Chat (IRC)

Index

Customer Reviews

5 star

4 star

3 star

2 star

1 star

Running a command every other week

Now that we have looked at the basics of cron, how would you set up an entry to run a command every other week? You may be tempted to try something like the following code:

             *  *  *  *  0/2   /path/command

That means to start on Sunday, and then run every other Sunday, right? No, this is wrong, but you often see this given as a solution on websites. Cron doesn't actually have a built-in way to do this, but there is a work-around.

How to do it...

The following are the steps to run a command every other week:

Create the following script in your home directory and name it cron-weekly1 (feel free to cut and paste):

#!/bin/sh
# cron-weekly1
# Use this script to run a cron job every other week
FN=$HOME/cron-weekly.txt
if [ -f $FN  ] ; then
  rm $FN
  exit
fi
touch $FN
echo Run the command here

Make the script executable by running the following command:
```
chmod 755 cron-weekly1
```
Under your user account run by running the following command:
```
crontab -e
```
Add...

Linux Utilities Cookbook

By : James Kent Lewis

Linux Utilities Cookbook

By: James Kent Lewis

Overview of this book

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Current Title:

Linux Utilities Cookbook

Running a command every other week

How to do it...