Book Image

Linux Utilities Cookbook

By : James Kent Lewis
Book Image

Linux Utilities Cookbook

By: James Kent Lewis

Overview of this book

<p>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. <br /><br />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.</p> <p>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.</p> <p><br />Based on the author's extensive experience, there is a section on best practices that every Linux user should be familiar with.</p>

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Linux Utilities Cookbook
James Kent Lewis
Oct, 2013 | 224 pages
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Table of Contents (19 chapters)
Linux Utilities Cookbook
Linux Utilities Cookbook
Credits
Credits
About the Author
About the Author
About the Reviewers
About the Reviewers
www.PacktPub.com
www.PacktPub.com
Preface
Preface
Free Chapter
1
Using the Terminal / Command Line
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
2
The Desktop
The Desktop
Introduction
GNOME 2
KDE desktop
xfce
LXDE
Unity
Mate
3
Files and Directories
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
4
Networking and the Internet
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
5
Permissions, Access, and Security
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
6
Processes
Processes
Introduction
Understanding processes
Examining processes with ps
Examining processes using top
Changing priorities with nice
Observing a process using the /proc filesystem
7
Disks and Partitioning
Disks and Partitioning
Introduction
Using fdisk
Using mkfs to format a drive
Using fsck to check the filesystem
Logical Volume Management (LVM)
8
Working with Scripts
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
9
Automating Tasks Using Cron
Automating Tasks Using Cron
Introduction
Creating and running a crontab file
Running a command every other week
Reporting the errors from a crontab file
10
The Kernel
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
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
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
Index

Using man pages

The man utility is an interface to the local reference manuals. It is used to quickly find information on programs, utilities, functions, and other topics. The man utility will accept several options; however, the usual invocation is simply man page, where page actually refers to a topic. You can even run man by itself to learn how to use it.

The following is a screenshot of the command man man:

Running man on a page displays that topic of interest. The spacebar is used to page down, and Q is used to quit. Pages (topics) are presented in a more or less standard order with these possible section names: NAME, SYNOPSIS, CONFIGURATION, DESCRIPTION, EXAMPLES, OVERVIEW, DEFAULTS, OPTIONS, EXIT STATUS, RETURN VALUE, ENVIRONMENT, FILES, VERSIONS, CONFORMING TO, NOTES, BUGS, AUTHORS, HISTORY, and SEE ALSO.

man shows the first page found, even if there are more pages in other sections. For example, suppose you are looking for information on how to code the readlink function in your C program. You might try the following command:

man readlink

It brings up a page, but of the command readlink and not the C function. Why? Because it shows the first page, unless you specify the section number before the page. Well, how do you know what that is? You can run man with the -a option in the following manner:

man -a readlink

This brings up the command readlink as before. Now press Q to quit. The page goes away, but instead of terminating, the man session shows something as follows:

Big4 /lewis/Fedora/17 # man -a readlink
--Man-- next: readlink(2) [ view (return) | skip (Ctrl-D) | quit (Ctrl-C) ]

This is giving you a choice: pressing Enter will show the next page (topic), Ctrl + D will skip to the next topic, and Ctrl + C will end the man session. Pressing Q when you are on the last topic will cause man to terminate normally as before.

So what if you already know that you want the page from section 3 and load it directly? You can specify it in the following manner:

man 3 readlink

This will skip the first two and go right into the page for readlink out of the POSIX Programmer's Manual.

Here is a list of the section numbers and their names:

  • 1: Executable programs or shell commands

  • 2: System calls (functions provided by the kernel)

  • 3: Library calls (functions within program libraries)

  • 4: Special files (usually found in /dev)

  • 5: File formats and conventions (for example, /etc/passwd)

  • 6: Games

  • 7: Miscellaneous (including macro packages and conventions), for example, man(7) and groff(7)

  • 8: System administration commands

  • 9: Kernel routines

The local reference manuals can be a great source of information. They contain a wealth of data on just about everything in a Linux system. Unfortunately, they do have some drawbacks. Most are well-written and make sense. Some are, well, rather horrible. When this happens, there are other places to find help.

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