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CentOS Pulse #1003 - 1 May 2010


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Update. Translations are now online in Spanish, Traditional Chinese and Simplified Chinese. Many thanks are due to our translators for their help.

1. Foreword

Welcome to another release of CentOS Pulse. After the recent release of RHEL 5.5, we have been allowed no rest at all as "The Upstream Vendor" announced their release of RHEL 6 Beta for public testing just over a week ago.

Have fun reading,

The NewsletterGroup.

Frank Cox

2. Interview

My name is Frank Cox. I own and operate a movie theatre in Melville, Saskatchewan, Canada, and I have been involved with computers for over 30 years. Over the course of time I have performed consulting and miscellaneous programming jobs for everything from surveyors to oil drilling companies. The most unusual program I ever wrote was for a vending machine.

About ten years ago the owner of a small publishing company asked me to write some software to manage his classified ads. One thing led to another, as this sort of thing has a habit of doing, and I became the system administrator, programmer and general "computer guy" for that publishing company. As his company grew and expanded, his computer requirements grew with it and now his operation runs on four CentOS-based servers. Some of his operations used to be contracted out to a hosting company but now everything is done in-house.

I administer all of his systems remotely from my office in the theatre and do automatic nightly data backups to a fileserver located in my basement.

I started installing CentOS on the publishing company's computers sometime around 2006. Having used Red Hat & Fedora previously, CentOS was the most logical choice for an operating system and I haven't had any reason to regret my decision.

The web and email server runs apache and sendmail. The main application server is a LTSP server with a half-dozen Neoware Capio 616 thin clients; they are what the office employees use to do their work. There are also some remote workers who access the application server through VNC-over-ssh and, of course, I do the same thing to handle the administrative tasks that are required from my own office, three blocks down the street from the publishing company.

The main software in use on the desktops are custom-written applications that I have made to handle the advertising databases, subscriptions and pretty much every other aspect of the business. The papers are laid out with the Scribus desktop publishing program. The company owner does the accounting with LedgerSMB.

There is one machine that does nothing but create the plates for the presses. I wrote a program to handle this job but it is so computationally intensive that it needs to run on its own separate machine. That machine's name is "jack" because it runs a "RIPper" program!

Another machine answers the telephone and the fax lines. It records and routes messages and faxes. Its final task is to email notifications and messages to the appropriate recipients.

The custom programs are mostly written in C, with ncurses for screen handling. My favourite programmer's editor is Geany.

I have CentOS on every computer that I use. What can I say? ... CentOS is the "perfect" operating system!

Geerd-Dietger Hoffmann

3. Red Hat Enterprise Linux 6 Beta

The RHEL 6 Beta journey from a very personal perspective, by GeerdDietgerHoffmann.

I could not get my hands quickly enough on the beta release of what will eventually become CentOS 6. I read the release notes and instantly started fighting for one of the limited download slots. Because so many people wanted a copy and Karanbir had not then released a torrent file, everyone was thrashing the RH servers. But eventually I got a copy and I started installing it right away. One of the first things you notice after the standard keyboard / language setup is that the file system is ext4, this was expected, but also XFS and Btrfs will be available. The next thing that could be seen in the 'Fedora-esque' release is the separation of predefined install targets. Most noticeably:

For now, I have only been able to try the Desktop and the Development Workstation but other installs may follow. After selecting what I wanted, I clicked next and it started installing right away. There was no sign of "Ok do you really want to go" or "Now we have all the data, DO IT", no. Clicking on next and it started copying the packages. But thinking about it, why do we need that type of screen, anyway? Unfortunately I first selected minimal and then somehow managed to click on next but, as I wanted to see the packages, this was the first real WOW moment. It is worth mentioning that there is python 2.6, OpenOffice 3.1 and the kernel is based on 2.6.32 (2.6.32-19.el6) but this might change by the time of the actual RHEL 6 release. After rebooting the next thing that was noticeable is the really nice Splash screen with a little circle that slowly fills up and then becomes the logo we all know so well. (I will try and make a video). There are no surprises with the software that is installed, the only thing that came to my attention was that in the standard desktop install there was the Virtual Machine Manager. I take this as a sign for the strong focus on Virtualisation, as this release has KVM as standard. Because of the newer library versions and the general newer software, programs like cheese can now be run. This makes the life of the people who run the Enterprise Class OS as a desktop so much easier. Unfortunately the network configuration screen is missing from the setup so the network didn't operate straight out of the box but just enabling it had it running. Then I tried to see if all of the multi-media things were working but the Music and Videos folder was empty. Let's hope that RH will put some nice little goodies in there before the final release. Sound and screen detection work without any problems and thanks to support for nVidia graphics, direct rendering worked out of the box. Now some info for the developers: Eclipse comes with loads of plugins preinstalled like PyDev, SVN, C/C++ and even an RPM Wizard can be found. Of course there is also Emacs and Vim in respectable new versions with loads of updates.

Based on Fedora 12, which was released in the autumn of 2009, RHEL 6 beta brings Gnome 2.28, KDE 4.3.4, Firefox 3.5, Thunderbird 3, PostgreSQL 8.4, MySQL 5.1, OpenJDK 1.6 and GCC 4.4

Timo Schoeler

4.1. Alternative backup tools, Part one.

Most of you will know of tools like dump/restore (more old school), which work on basis of block devices or rsync, which operates at the file system level.

As those tools are widely known, I'd like to talk about a tool that I've been using for a number of years now, duplicity. The word obviously hasn't been widely spread because, although it's one of the best open source backup utilities I've ever used, it gets very little mention. It uses librsync, which makes incremental archives space efficient and network-friendly, as only the deltas are transferred. Furthermore, in contrast to rsync, duplicity can store the backup data encrypted, using GnuPG to achieve a high level of security.

Thus one can copy the backup data to any untrusted (in terms of spying) hosting provider -- duplicity supports ssh/scp, local file access, rsync, ftp, HSI, WebDAV, and Amazon S3. So you could even use some cloud to hold your backup data! :)

However, there are some things to keep in mind: It's a beta product. It supports deleted files, full Unix permissions, directories, symbolic links, fifos and device files but not hard links.

If you want to use it, you can find duplicity in the RPMforge repository. However only an older version, 0.4.11 (released 2008/05/05), is available from that repository as of this date.

After installing duplicity, let's perform a simple test backup. Simple, in terms of meaning that we omit the setting up the encryption keys, as maybe your environment is safe enough to keep backups unencrypted. Let server A be the machine you want to backup data from, whilst server B is the machine that will store the backup data. Both machines are accessible via SSH. The best practice is to set up a dedicated backup user, with the least permissions as possible, though a normal user account should be okay.

Let's pretend that the contents of directory /srv, on server A, should be in the backup to be stored in the subdirectory 'server-a' (in case you want to backup multiple machines) of the user 'backup', on server B:

duplicity --full-if-older-than 2W --no-encryption /srv/ rsync://server-b://backup/server-a

This will cause duplicity to:

The next step might be to write a wrapper script that could be run by cron which then, maybe, sends you an email message with the status of the backup upon its completion.

5. Tip Of The Newsletter

If you have a good tip or know of a really useful program that you would like to share, please send us an email.

5.1. Automated editing of section based configuration files

Sometimes it makes sense to automate the editing of configuration files, e.g. during kickstart process.

This example shows a one-liner which sets the multilib_policy configuration option to the value best within the main section of a yum.conf file.

awk '/section/{f=0}/^\[main\]/{f=1;print;print "multilib_policy=best";next}f && /multilib_policy/{next} {print}' /etc/yum.conf > /etc/yum.conf.tmp && mv /etc/yum.conf{.tmp,}

This technique could be used for many purposes, e.g. enabling or disabling repositories, for example.

6. Jokes and Funny Stuff

6.1. Conclusions

There was a pilot flying a small single engined charter plane, with a couple of very important executives on board. He was coming into land at Seattle airport through thick fog with less than 10m visibility when his instruments went out. So he began circling around looking for landmark. After about an hour, the plane starts running low on fuel and the passengers are getting very nervous. Finally, a small opening in the fog appears and he sees a tall building with one guy working alone on the fifth floor. The pilot banks the plane around, rolls down his window and shouts to the guy: "Hey! Where am I?". To this, the solitary office worker replies: "You're in an aeroplane." The pilot rolls up the window, makes a 180 degree turn and proceeds to execute a perfect blind landing on the runway of the airport, 5 miles away. Just as the plane comes to a halt, so does the engine -- as the fuel has run out.

The passengers are amazed and one asks the pilot how he did it. "Simple", he replies. "I asked the guy in that building a simple question. The answer he gave me was 100% correct but absolutely useless. Therefore I deduced that it must be [GENERIC COMPANY]'s Technical Support Office and, from there, I knew the airport was 5 miles away." source

6.2. Just imagine going through airport security with that

Once upon a time, before laptops . . .


Geerd-Dietger Hoffmann

7. User Desktops

The following picture is of the desktop of a CentOS user. Please send us your picture(s), if you would like to have yours featured. Of course all machines have to run CentOS to be accepted. Please blur any private content.


Timothy Lee

8. CentOS Errata

This section highlights the most severe security updates for each supported CentOS release, whilst providing a summary and short links to the reference of the security issue.

8.1. CentOS-3

8.2. CentOS-4

8.3. CentOS-5

No critical updates were released in April 2010.

9. Upcoming Events

The CentOS Promo Special Interest Group organizes the CentOS presence (booths, presentations, etc) at various conferences and trade shows. Here we highlight upcoming events. If you are interested in helping out, please join the Promo SIG.

We are all gearing up for the LinuxTag in Berlin. If you would like to come along and help, just add yourself to the wiki page. We will also be holding the second CentOS Beer event in Berlin, so feel free to join us. :)

10. Contributing to CentOS Pulse

We are always on the look-out for people who are interested in helping to:

Please see the page with further information about contributing.

Finally if you would like to appear in the newsletter, you will have to have contributed positively to the CentOS community and then, hopefully, be noticed by one of our reporters. ;-)

2023-09-11 07:23