Back to Newsletters KEYWORDS= Davrom Consulting Newsletter - Issue # 52 - Dated: 14 Dec 2012 From the desk of David Clark Just like dragging out our little old humble Christmas tree of 26 years, I am again prompted to insert the little ASCII Christmas tree that you all have seen for the past 11 years, some of you have seen it since the 80s/90s. As usual we are here over the Christmas and New Years Eve break doing business as usual. I would like to thank all of our customers for their continued support by using our services over the years and along with our colleagues in the field and readers of this newsletter, I would like to wish you all a very Merry and Blessed Christmas and a prosperous and Happy New Year.
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I would like to thank the reader for their time in reading this newsletter. David.M.Clark UNIX Quote Given Steam has come to Linux, Linux is now the best priced gaming platform to own. Linux is Linux, or is it? For those who have been following my newsletters for some years will know that I am a die-hard Red Hat, Fedora and CentOS fan and my choice of desktop has always been KDE. To some this is just "so what" and to a few others who use Linux day to day would be ready to hotly debate me on my choice of Linux platforms tending their case for their choice of a different Linux as a better way.... So I guess I have pointed out here that Linux means you have a choice; you have a choice of Linux version based on different development strands from different providers and a range of X-Windows based graphical desktops to choose from. So given you have such choices, is Linux, Linux? We all know that the founding father (leader and developer) of Linux is Linus Torvald, and along with Linus and countless other Linux developers and code cutters throughout the world, we owe a sincere and well deserved word of gratitude towards these excellent I.T professionals. But while Linux is based on the same core (kernel) structure development (for the most part), there are several mainstream Linux versions (if you like) that the Linux brand names are based on. They all do the same thing and provide the same features, so let us look at some of the mainstream Linux vendors that hold the majority of installations in the business and personal desktop usage world today. Red Hat Linux: This was the second version of Linux I installed and coming from a traditional UNIX background, I somehow madly kept going with the copies of Red Hat that came out stuck to the front of I.T magazines released at the time. Red Hat released free versions of their Linux cut up until Red Hat 9.0, and then went into the business arena with their commercial version of Enterprise Linux, Red Hat EL/ES versions. Out of the Red Hat structure came other derivations of Linux such as Mandriva (previously called Mandrake). The two versions I actively use and install for customers are Fedora (best for desktop users) and CentOS which is more suited to being the "free" server version of the Red Hat Enterprise releases and follows the operating system version releases of Red Hat to the letter (unlike Fedora who are changing their release every 6-12 months - hence better suited to the desktop environment with regards to later hardware support). Debian is another large desktop/server release of Linux and differs in its approach to installed software package management (Debian based Linux uses apt-get whereas Red Hat is based on their rpm/yum based package managers). I liken Debian in my thinking as being like Red Hat in that Debian has formed the base of quite a few versions of Linux, the largest and most active of these being Ubuntu. Ubuntu would most likely be the most installed and commonly used Linux desktop in the US and possibly Australia, and continues to be developed by Canonical Ltd. Being a KDE user, I have installed and used the KUbuntu version and to me it is just Linux, just like my beloved Fedora. Another huge player in Linux, and more so in the server market, is Suse Linux. Suse has a large install base and continues to be developed under the Attachmate Group, who brought out the owners of Suse, Novell some time back. Suse originated from Germany/Europe, and so is widely used in Europe and the UK. There are a great many more Linux releases such as Mint, SeLinux, Arch, Mandriva and the list goes on as there are new 'spins' of Linux developed all of the time - most based on either Red Hat or Debian. You would also be amazed at the number of devices (phones, cameras, routers, TV controllers) that are based on, or are pure Linux on a chip so to speak. And I have to mention here Android for mobile phones and tablets, being based on Linux. For all of these versions of Linux for the desktop user, there are a range of X-Windows interfaces you can use. I have already mentioned KDE and I would recommend using KDE if you are coming from the Windows/MAC environment and setting your menu display to the Classic Menu View (Right-Click on the launcher to select this option). Some people find the Gnome desktop very good and Ubuntu are very heavily into promoting their Unify desktop. Other desktops include Xfce and LXDE. The beauty is you can have multiple desktop managers installed and you can switch between each one to try them out..... that being said, so far I haven't left KDE since 2000. So from a front end interface, Linux is still Linux, regardless of the version behind it. But what about the packages and structures I alluded to earlier? As already mentioned, different versions of Linux use different software package managers that allow you to install or update software on your Linux installation. They all essentially perform the same function: Debian uses apt-get, Red Hat uses yum (rpm) and Suse uses Yast. If you are a command line shell user like myself, then the GUI exists as an add-on to what you do, not as a replacement of your command line antics. Some fundamental difference exist between Red Hat, Debian and Suse with regards to the locations of system configuration files. For example, Red Hat stores its network configuration files under /etc/sysconfig whereas you won't find this particular directories under other versions of Linux. If you were to set up an IPSec tunnel between a Red Hat based Linux and a Debian based Linux, the locations of files such as ipsec.conf would be in different locations under the standard /etc directory. But at the end of the day, the configuration files themselves are usually identical in structure if they are from the same core solution. So based on the differences in some areas of config file locations and server setup/install procedures, despite the idiosyncrasies of each 'version', Linux still provides a unified and powerful desktop/server solution but being true GNU/Open Source, it still leaves the user and administrator alike a freedom of choice of which Linux they want and need to run. So Linux is possibly Linux after all? From the Trenches Some comic or not so comic relief from the support days gone by. sh exec error, could not fork to a lower shell. One afternoon I had finalised the setup of my SCO UNIX 3.2v2 desktop server and back in those days, it was about 10-12 1.44MB floppy disks to complete the installation. Then a few more to get the packages loaded for TCP/IP to get you onto the network. I then had to restore my HOME directory from the backup floppies that I had. My task was completed and I happily went home excited that I had my new desktop ready to work with the following work day. To my horror, when I tried to login to the server the next morning it came back with an error "exec error: cannot fork to a lower level shell" or words to the this effect. In UNIX terms it meant the system was out of memory or the hard disk was in such a state it could not allow me to login and run the /bin/sh (shell environment). I rebooted the server and tried to find the issue by using my emergency boot floppies - but to no avail. Everything looked ok but was just not working. So that morning I started to load everything again thinking something had become corrupt overnight. One of my work colleagues (the office prankster) came in and when he saw me re-installing went into a state of shock as he had played a prank on me, that had gone horribly wrong in his eyes. He had accessed my desktop server and knowing enough about UNIX he had edited the profile files (.profile and /etc/profile) for the root and my logins to show me a bogus message and kick me straight back out of the system. He had of course put in a work-around which he was going to tell me when he saw I had fallen victim to his prank - which had backfired on him and now he was concerned what management would say...... but we never involved them and given I had happily completed my installation again, was none worse the wear for it. What it did tell me is: don't give anyone else in the office the root password to your server. Needless to say, some harmless revenge was exacted on my colleague some time later. Tech Tip Fun with the boxes command The Linux boxes command is used to spruce up your boring ASCII text reports and the like to give you a bit more fun with your Linux life. You can use the different options to make things in text appear a little more lively. For example: the following 'boxes' commands produce the following output: echo "Merry Christmas" | boxes /*******************/ /* Merry Christmas */ /*******************/ echo "Guard dog on duty" | boxes -d dog
__ _,--="=--,_ __
/ \." .-. "./ \
/ ,/ _ : : _ \/` \
\ `| /o\ :_: /o\ |\__/
`-'| :="~` _ `~"=: |
\` (_) `/
.-"-. \ | / .-"-.
.---{ }--| /,.-'-.,\ |--{ }---.
) (_)_)_) \_/`~-===-~`\_/ (_(_(_) (
( Guard dog on duty )
) (
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echo "and for cat lovers" | boxes -d cat
/\ /\
|`\\_,--="=--,_//`|
\ ." :'. .': ". /
==) _ : ' : _ (==
|>/O\ _ /O\<|<
| \-"~` _ `~"-/ |<
>|`===. \_/ .===`|<
.-"-. \===' | '===/ .-"-.
.---{'. '`}---\, .-'-. ,/---{.'. '}---.
) `"---"` `~-===-~` `"---"` (
( and for the cat lovers )
) (
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