Linux Certifications – How Valuable?
By J Reece

Computer certifications in general

Acquiring certification indicates that you have completed the steps and have the knowledge required to perform at a specified level as an IT professional. Certification also proves to your employer and clients that your expertise is confirmed by a recognized industry organization and can increase your salary, enhance your skills and make your job more satisfying. If nothing else, it can keep your resume from being rejected by the resume-scanning programs now used by every Human Resources department these days.

Why a Linux certification?

The number of job ads calling for some knowledge of Linux has risen by nearly 100% over the last year. On the other hand the number of applicants choosing Linux certification hasn’t risen proportionally. Part of the reason for this anomaly is that employers generally haven’t put much faith in Linux certifications and therefore there has been little demand for them. Also, many of the Linux jobs advertised are for more senior and technical roles such as programmers and developers – skills that far outweigh the level that are tested on some Linux certification tracks. All that appears to be changing however, with Linux becoming ever more mainstream and people with Linux skills becoming more in demand.

Will Linux certification really help?

While actual work experience with Linux or any computer technology will always count for so much more than any piece of paper, gaining Linux certification certainly won’t do your credentials any harm. The demand for credentials in every field, computer-related or not, is increasing and one has to keep up with the pack. Having that certification ticket punched may not make your resume stand out in a positive way, but not having it might make it stand out in a negative one. Large bureaucratic IT organizations take them more seriously than groovy startups if that’s the environment you’re looking to work for. There are several specific situations where I’ve found computer certification in general to be of benefit. First, certification courses offer better knowledge retention than the typical corporate training course since you do have to study to pass an exam, even if only a multiple-choice one. Another one is where you have related experience and are moving (or were moved) into a new environment. In my case I was re-orged from a Unix-centric to a Windows-centric IT environment. Getting a Microsoft System Administrator certainly helped come review time. Finally, if you have a discrimination issue, such as the common one that as an older tech worker you’re skills aren’t up to date. If push comes to legal shove human relations people, lawyers, and judges do take evidence of continuing education very seriously.

Which Linux certification?

There are several options to choose from and, given the amount of time and money that you’ll need to invest into gaining your Linux certification, you’ll want to be sure that you make the right certification track choice to begin with. For those new to Linux then the entry-level, vendor-neutral certifications offered by CompTIA and LPI an appropriate choice. However, these involve only multiple-choice tests and as a result have rather less credibility with technical managers. If you are already working with Linux then one of the proprietary, more difficult, and more expensive Linux certifications (Red Hat, Novell) would be better suited. Like the respected Cisco certifications these certs involve rigorous hands-on practical exercises under severe time constraints and have much more credibility with technical managers. The cost is significant, especially if you have to retake the test, as almost 50% of Red Hat wannabes fail the first time around. Given that there are numerous distributions of Linux available one problem of Linux certifications is that there is no central organization that can set the certification standards and ensure that the candidates meet those standards. What this means is that you have quite a degree of freedom to choose which certification track is right for you, but you equally need to be sure that the one you choose will meet your end needs. As with any other certification track that you take, Linux certifications can be taken by way of instructor led courses or you can undertake a regime of self-study on your own. Don’t get too bogged down on deciding which distribution is better or is more likely to result in a job at the end of the day. While there are obvious differences between the various Linux distributions a degree of competency in one flavour will set you up to transition to the others if need be at a later stage.

Created by J Reece of iSierra Consulting, at http://www.isierra.net/

Linux, Mac, *nix expertise in the Reno-Tahoe area.

Linux – Getting the Correct Time
By Richard N Williams

Ensuring a computer is not only displaying the correct time but that it is being maintained accurately is not as straight-forward as it first sounds.

Most Linux systems have two clocks. The hardware clock, also known as the CMOS of Bios clock, is usually a simple crystal oscillator with battery back-up that maintains time when your system is off or boots up. This clock is usually located on the motherboard and will run all the time, however these clock chips tend to lose time as the computer ages and the battery weakens.

The other clock, the system clock, is a software clock and it starts when you boot up your system often getting an initial time from the hardware clock. System clocks keep time by adding seconds on to a prime epoch, a base time that for Linux and Unix, began at midnight on January 1, 1970.

However, the hardware clock is a cheap electronic oscillator and cannot maintain time to any useful degree of accuracy. They often drift several seconds a day which for day-to-day process is probably adequate but with time sensitive applications it can cause serious problems.

A better way is to set the system clock using the time from a NTP (Network Time Protocol) time server. These dedicated time servers get a UTC (Coordinated Universal Time) time from an atomic clock which are the most accurate time keepers in the world, not losing a second in time in several millions of years.

Dedicated NTP servers use either a radio receiver to pick-up a radio time and frequency broadcast which are transmitted by several national laboratories or by using the timing signal broadcast from the GPS network.

Linux uses a NTP service called NTP Daemon (ntpd). This uses NTP to adjust the system clock for any drift in time as it frequently check the UTC time source.

To configure the NTP daemon the ntp.conf file in the /etc directory can be used. From here more than one time server can be used as a reference and also the frequency it is checked can also be altered.

Richard N Williams is a technical author and specialist in atomic clocks, telecommunications, NTP and network time synchronisation helping to develop dedicated NTP clocks. Please visit us for more information about a network time server or other ntp server solutions.

Linux Boot Process
By Erik Schweigert

As many people have often wondered, how does the Linux/Unix operating system boot? How could I put in a process to run during boot so that I do not have to start it every time manually? To do this one has to understand the basic

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environment procedure that is currently in place to add anything to it.

On a typical Linux system, I prefer Debian, the bootloader points to the kernel which in turn points to a file under /etc known as inittab. The interaction between the bootloader and the kernel is complex enough for another article.

1. The /etc/inittab is a file that contains a set of instructions to call a specific directory under the /etc directory. It is a Shell script that looks something like this:# /etc/inittab: init(8) configuration.
   # $Id: inittab,v 1.91 2002/01/25 13:35:21 miquels Exp $

   # The default runlevel.
   id:2:initdefault:

   # Boot-time system configuration/initialization script.
   # This is run first except when booting in emergency (-b) mode.
   si::sysinit:/etc/init.d/rcS

2. The system then calls the /etc/init.d/rcS shell script. This script then executes each shell script found in /etc/rcS.d/ directory. When an application is added to the system it will place its startup script in either the /etc/rcS.d/ or the /etc/rc2.d/ directory. This set of scripts are run initially and are system specific and should never be tampered with. After this set of scripts spawns off each process the /etc/init.d/rcS script then calls all files under /etc/rc2.d/ directory. The /etc/rc2.d/ directory is usually application software and not software required specifically for the system.Each file in these directories has a S(for start) and a number. For example: S43portmap. The number does not mean it will be the 43rd process started, but instead is used to stagger which process is started. Thus, if you wanted something to start before or after S43portmap you would set the prefix to be S40 for before the S43portmap and S50 for after the S43portmap.
3. If you wanted to add your own application to be run you should always add it into the /etc/rc2.d/ directory. The /etc/rc2.d/ is the default runlevel used on most Linux systems.
4. If you find yourself in the /etc/rc2.d/ directory you may notice that each file is actually symlinked back to the /etc/init.d/ directory. You are in fact correct. Its actually pretty neat if you think about it, as you could just create a symlink with a different number to start any of these scripts at a different time. This also gives the flexibility to the user to easily modify the boot process for his/her system.

Now show me how to do that in Windows!

For more information related to Linux and UNIX head over to linuxtechutopia.com

Erik is an avid Linux user and has experience with a wide variety of Linux/Unix based systems. In his spare time he likes writing software (C/C++/Perl/PHP/BASH/Python) and experimenting with different Linux distributions. He is starting to build a wide variety of articles Unix driven (what a surprise) that hope to inform those just getting into Linux on his website.

http://www.linuxtechutopia.com