On GNOME, you use the Themes Preferences tool to select or customize a theme। Themes control your desktop appearance। When you open the Theme tool, a list of currently installed themes is shown। The GNOME theme is initially selected। You can move down the list to select a different theme if you wish। If you have downloaded additional themes from sites like art.gnome.org, you can click the Install button to locate and install them. Once installed, the additional themes will also be displayed in the Themes Preferences tool’s listing. If you downloaded and installed a theme or icon set from the Fedora repository, it will be automatically installed for you. The true power of Themes is in the ability it provides users to customize any given theme. Themes are organized into three components: controls, window border, and icons. Controls covers the appearance of window and dialog controls such as buttons and slider bars. Window border specifies how title bars, borders, and window buttons are displayed. Icons specify how all icons used on the desktop are displayed, whether on the file manager, desktop, or the panel. You can mix and match components from any installed theme to make your own theme. You can even download and install separate components like specific icon sets, which you can then use in a customized theme. Clicking the Customize button will open a Themes Details window with panels of the different theme components. The ones used for the current theme will be already selected. In the control, window border, and icon panels you will see listings of the different installed themes. An additional Color panel lets you set the background and text colors for windows, input boxes, and selected items. You can then mix and match different components like icons, window styles, and controls, creating your own customized theme. Upon selecting a component, your desktop automatically changes, showing you how it looks. One you have created a new customized theme, a Custom Theme entry will appear in the theme list. To save the customized theme, click the Save Theme button. This opens On KDE, you can select the Password panel in the Security entry on the KDE Control Center. Here you can select a picture for your account. Contact information is handled by other applications, like Kontact for mail and user information.
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Introduction
A shell is a command line interpretor. It takes commands and executes them. As such, it implements a programming language. The Bourne shell is used to create shell scripts -- ie. programs that are interpreted/executed by the shell. You can write shell scripts with the C-shell; however, this is not covered here.
Necessity of Structured Shell Programming
Shell scripts remain a staple of the business world.With high development costs, it is not practical to develop everything in a high-level language. Many business processes are simply a matter of following a series of steps, after which the results are labeled and archived.This is the very type of activity scripts are made to handle. Over time, shells have collected new features, often by copying the capabilities of other shells. In his book, The Humane Interface, Apple Macintosh interface designer Jef Raskin once spoke with a pilot regarding the design of the plane’s autopilot.The device was designed with five ways to enter coordinates.The reason for this design was to reduce training costs by emulating other autopilots. However, a pilot pointed out that the operator of the aircraft is responsible for knowing how to operate every piece of equipment, and that meant he had to know how to adjust the autopilot in each of the five ways.
Many shells, including Bash, have developed a mixture of features with specialized or arcane applications. Like the autopilot, it is not always clear how these features should be
used nor which features are provided primarily for compatibility.Too often, poorly designed scripts are all-but illegible to another programmer, or even to the same programmer a few months after a script was hastily assembled.
This presents a problem for serious business scripts.The cost of developing a highlevel language solution is high, but a disorganized shell script can be expensive to maintain
over time. As the needs of the business change, and the shell script is modified by successive generations of programmers, the problem escalates.
As a rule of thumb, business programs never go away.At one place I recently worked,what started off as a simple shell script used to print reports gradually evolved into a Web-based reporting system complete with personal customizations and secure access.
The original programmer had no idea what his script would become. Because of the essential openness and complex syntax of Bash, it’s to the benefit of any serious project to adapt some kind of standard. Bash is very forgiving, but the costs are not. For example, there are many ways to add 2 + 2 in Bash. Like the autopilot anecdote, it’s not practical to expect the programmers who maintain the scripts to have to deal with this kind of redundancy. Likewise, shell word quoting is sometimes optional, sometimes required, depending on the context. A command that works with one form of quotation can suddenly stop working when different data appears in the quotes. Issues like shell word quoting, specialized capabilities, or portability features, when abused, can lead to increased maintenance and long-term development costs.
Many shells, including Bash, have developed a mixture of features with specialized or arcane applications. Like the autopilot, it is not always clear how these features should be
used nor which features are provided primarily for compatibility.Too often, poorly designed scripts are all-but illegible to another programmer, or even to the same programmer a few months after a script was hastily assembled.
This presents a problem for serious business scripts.The cost of developing a highlevel language solution is high, but a disorganized shell script can be expensive to maintain
over time. As the needs of the business change, and the shell script is modified by successive generations of programmers, the problem escalates.
As a rule of thumb, business programs never go away.At one place I recently worked,what started off as a simple shell script used to print reports gradually evolved into a Web-based reporting system complete with personal customizations and secure access.
The original programmer had no idea what his script would become. Because of the essential openness and complex syntax of Bash, it’s to the benefit of any serious project to adapt some kind of standard. Bash is very forgiving, but the costs are not. For example, there are many ways to add 2 + 2 in Bash. Like the autopilot anecdote, it’s not practical to expect the programmers who maintain the scripts to have to deal with this kind of redundancy. Likewise, shell word quoting is sometimes optional, sometimes required, depending on the context. A command that works with one form of quotation can suddenly stop working when different data appears in the quotes. Issues like shell word quoting, specialized capabilities, or portability features, when abused, can lead to increased maintenance and long-term development costs.
The Origin of Linux
The Linux operating system was created as a hobby by a young student, Linus Torvalds, at the University of Helsinki in Finland. Linus, interested in the Unix clone operating system Minix, wanted to create an expanded version of Minix with more capabilities. He began his work in 1991 when he released version 0.02 and invited programmers to participate in his project.Version 1.0 was released in 1994.
Linux uses GNU General Public License (GPL) and its source code is freely available to everyone. Linux distributions, CD-ROMs with the Linux kernel and other software ready for installation, do not have to be free, but the Linux source code must remain available. Making source code available is known as distributing open source. The word “Linux” is properly pronounced using a Swedish accent, making it difficult to say in North America. It is most often pronounced with a short “i” and with the firstsyllable stressed, as in LIH-nicks, but it is sometimes pronounced LYE-nicks (the anglicized “Linus’ Unix”) or LEE-nucks. Strictly speaking, Linux refers to the operating system kernel that starts and manages other programs and provides access to system resources.The various open source shells, compilers, standard libraries, and commands are a part of another project called GNU. The GNU project was started by the Free Software Foundation (FSF) as an attempt to create a free version of Unix.The main Linux C compiler, gcc, is a part of the GNU project. There is also a GNU kernel project, but the Linux kernel has largely superseded thiseffort.
X Windows is also not strictly a part of Linux. Xfree86, the open source version of X Windows, was adapted to the Linux operating system and was released under a different license.
Linux uses GNU General Public License (GPL) and its source code is freely available to everyone. Linux distributions, CD-ROMs with the Linux kernel and other software ready for installation, do not have to be free, but the Linux source code must remain available. Making source code available is known as distributing open source. The word “Linux” is properly pronounced using a Swedish accent, making it difficult to say in North America. It is most often pronounced with a short “i” and with the firstsyllable stressed, as in LIH-nicks, but it is sometimes pronounced LYE-nicks (the anglicized “Linus’ Unix”) or LEE-nucks. Strictly speaking, Linux refers to the operating system kernel that starts and manages other programs and provides access to system resources.The various open source shells, compilers, standard libraries, and commands are a part of another project called GNU. The GNU project was started by the Free Software Foundation (FSF) as an attempt to create a free version of Unix.The main Linux C compiler, gcc, is a part of the GNU project. There is also a GNU kernel project, but the Linux kernel has largely superseded thiseffort.
X Windows is also not strictly a part of Linux. Xfree86, the open source version of X Windows, was adapted to the Linux operating system and was released under a different license.
