Linux has been constantly changing over the past few years. Linux is a very dynamic Operating System and is continuously moving forward with new innovations and improvements.
Many of these changes are under the covers. Even though the user interfaces, such as the KDE and GNOME desktops, have changed over the years, the basics have remained the same and users of older versions of those and other desktops will be able to transition easily to the newer ones.
The biggest changes to Linux have been hidden from most users and are only visible to System administrators. Many of these changes, however, translate into a better experience of Linux for end users.
The following partial list of changes to recent releases of Fedora Linux are indicative of the rapid pace of development occurring. Most of these changes will appear in future releases of Red Hat Linux and other downstream descendants of Red Hat such as CentOS; some already have. You need to be prepared when they show up.
The Linux SystemV start scripts and the init program that have been used to manage the startup and shutdown sequence for all versions of Linux has been showing its age. The init program manages the startup sequence using the SystemV start scripts. This combination has been around since Unix was developed in the late 1960′s. System services were started serially and had to be started in the correct sequence or errors would occur.
The init program and the SystemV start scripts have given way to systemd. This new daemon, while compatible with the old SystemV start scripts, start the system services in parallel, and it only starts the ones that are needed. This results in a much speedier startup as well as saving considerable memory and CPU resources by not starting services until they are actually needed.
systemd requires learning a new set of commands and new ways of dealing with service management.
DBUS is an internal communication system for Linux. It enables Linux to communicate with various services about changes taking place in the system.
For example when a new hardware device is plugged in, this is detected and a message sent on DBUS to all services and programs that listen to DBUS messages. Thus when a USB storage device is plugged in, the Device Notifier in the System Tray on the desktop can notify the user that a new device has been added and allow the user to click on an icon to mount that device, as well as to open an application appropriate for the task at hand such as downloading photos from that device.
Another example is when a network cable is unplugged, the Network Manager can display that fact in another icon in the System Tray.
Although DBUS runs in the background, knowledge of DBUS is critical to understanding how and why services deal with changes in dynamic Linux environments.
The NetworkManager is a relatively new service that replaces the old network service. Using DBUS messages to receive notifications when network cables are plugged and unplugged, it can automatically make the correct connections. When a laptop is turned on NetworkManager seeks available wireless connections and automatically connects to known wireless networks using stored security configurations.
This new firewall service replaces the older IPTables firewall. It offers a more secure firewall because the IPTables had to restart every time a change was made. Despite the fact that this occurred very quickly, even a small window of opportunity can allow a cracker access to your system.
firewalld closes this tiny chink in the armor of your computer system and makes it harder for the bad guys to gain access. It also has a new set of commands to learn and a different structure from IPTables.
Despite the fact that firewalld is now available, IPTables will continue to coexist with it for the foreseeable future. But there are also changes in some rule syntax that improves IPTables but also means that upgrading to Fedora 18 will require learning that new syntax.
With Fedora 18, Anaconda, the installation program for Red Hat based distributions, has changed significantly. Instead of a serial wizard-like progression through the installation options, it is now menu-based and some sections can be skipped entirely. Many of the checks that take place after completing a menu section are done in parallel while you are making selections in the next menu item.
Once you understand the defaults and options of the new installation procedures you can make only the changes you need thus making the installation procedure significantly faster.
The vast majority of training classes available today do not cover most of these changes. Those that do only cover the ones that have been around since their last development refresh cycle—usually multiple years behind the times.
That is to be expected from the large corporate training houses because courses and certifications such as the LPI are only revisited once every few years. I have taught some of these classes and even the newest was developed from objectives that are now over two years old and use Linux distributions for their lab projects that are well past end of life.
Of course this obsolescence is determined in part by the need to sell the large numbers of class materials that are published at the beginning of each course revision cycle. Discarding huge numbers of preprinted materials would be wasteful on multiple levels and would detract from the bottom line.
The Millennium Difference
Millennium Technology Consulting LLC is a small company.
I cannot afford to have hundreds of copies of my course materials printed at one time. I have turned this into a competitive advantage because I only print my course materials when I plan to run a course. This not only saves trees, it saves me money and allows me to update my class materials prior to each class.
Whenever you attend one of my personally developed courses you can be sure that it will contain the very latest information available. Even when new features have not yet made their way from Fedora into Red Hat and then CentOS and other downstream distributions, many of them will eventually do so.
Will you be prepared when they do?
Contact Millennium Technology Consulting LLC to be ready.