Hard reset on linux command line.

Linux is not Windows and if reboot fail you usually still connect by SSH and do something. This commands will show you how to remotely hard reboot machine.

Hard reboot mean that shutdown scripts will not run and machine reboot immediately without syncing hard disk drives, shutdown applications etc, it’s like hitting the reset button on your server.

 

echo 1 > /proc/sys/kernel/sysrq

echo b > /proc/sysrq-trigger

This commands enable sysrq and after this calls fast reboot. If you want to force shutdown machine try this.
Force shutdown

 

echo 1 > /proc/sys/kernel/sysrq

echo o > /proc/sysrq-trigger

This came handy, when I had a server that had some IO error and it can no longer read from disk, only few cached binaries into memory kept it running (kernel, SSHD, bash), I could still access the machine via SSH but can no longer do anything, forcing the reboot as mentioned above was my only resort, and it worked like charm…

Wikipedia needs us!

Today I was working on something and had to check something related to the IP protocol so I went to the Wikipedia page. On the main page usually there is a chart and a message asking people to contribute so wikipedia can continue to be free, in the matter free as free of adds, free so profile matching and free of schemes to pay itself and it’s main collaborators. This time wikipedia had a message from it’s original founder.

You may cheek it here.

This message inspired me to make a small donation to help this project. Why don’t you do the same and help this and other opensource projects. The developers will enjoy your contributions and will keep improving the software or service.

Cheers,

Pedro Oliveira

What’s the best linux distribution?

Lots of people ask me what’s the best Linux distro, some say what’s the best for a newbie others want to setup a home server and some others want to build a gatekeeper. So what’s the best distro to accomplish all this?

To be sincere I like OpenSuSE a lot and I use it for all my personal things and my work laptops, but I wouldn’t recommend  it for server usage, I don’t recommend any of the desktops distros (aka distribution) for that matter due to a simple issue. The  desktop distros like OpenSuSE, Fedora, Ubuntu , etc have a small support cycle. This means that if you want to have security upgrades you’ll need to be constantly updating your server install.

For usage in a server environment I like to use SLES, RedHat and CentOS. The support cycle is great (at least 5 years), the stability and endurance of the OS is great in any of them.

Once again I prefer SLES, this is due to the great tools and support they provide.However I don’t say the same about RedHat support, whenever I need them I  had to find the solution on my own.

These are the two main scopes of Linux distros out there, the desktop and server, but they aren’t the only scopes where you have Linux. For instance if you want to have a firewall, proxy, content filter, qos, and traffic shaping I would recomend the excellent Endian FW (www.endian.it).

If you want to have your linksys/asus and other router working with linux, you may use dd-wrt, would you like to have an older computer as a

media center look at Geex-Box. A hacker distribution so you can test your systems security just download BackTrack. The list can continue and you will be able to find a distribution suited to your needs. Some may need just a live cd or dvd system, other a complete server suite like SME server (that will give you the same offer as Windows small business).

To conclude I don’t think there’s a better distro, there are differences and those differences make some people like one distro over the other.

Personally I like OpenSuSE and SLES.

Cheers,

Pedro Oliveira



Kde 4.3 – Innovation or just patching?

Recently I upgraded my KDE version 4.2 to the 4.3 and I’ve been using it for a few days now. As said before I don’t mind using betas and do some testing, but as with everything there is an exception, in my case it was KDE, I used the first KDE4 betas and come back to 3.5 then used the 4.1 when it was stable, then 4.2 and tried the beta 4.3… once again came back to the 4.2, now that is stable I’m using version 4.3, and for the first time in KDE4 I can say it’s stable. In my opinion KDE4 was released way to early, and although usable it was needing serious work around it. I’m a Linux user with several years of experience and didn’t have much trouble using it, but for instance my wife would go crazy, so till KDE4.3 she was using KDE3.5.

What changed in this last version of KDE that made me upgrade all my machines to KDE4.3?

The KDE community has fixed over 10,000 bugs.

Implemented almost 2,000 feature requests in the last 6 months.

Close to 63,000 changes were checked in by a little under 700 contributors.

If you want to read more about it just check this link.

All this made KDE4.3 more user friendly, more reliable, more polished and prettier.

So, what more can I say about it? JUST INSTALL IT AND GIVE A TRY you won’t be disappointed.

In conclusion is there innovation or just patching in KDE 4.3? Definitely both, there’s hundreds of new features and even more bug fixes. Both are equally important and KDE really need this ultimate push to be the ultimate Desktop Manger.

Cheers and see you next time

Pedro Oliveira

ps – bellow there are the install instructions and a vid of kde4.3 in action.

If you need help to install it just check the install instructions (from www.kde.org):

Debian KDE 4.3.0 packages are available in the unstable repository.

  • Fedora
    • Rawhide development repository, however the packages there may depend on other Rawhide packages and are therefore not suitable for installation on previous releases.
    • Unofficial Fedora 11/10 packages are hosted at the kde-redhat project.
    • Kubuntu packages are available for 9.04. More details can be found in the announcement on Kubuntu.org.
    • Mandriva provide packages for
2009.0 i586 2009.0 x86_64 2009.0 SRPMS
2009.1 i586 2009.1 x86_64 2009.1 SRPMS

Please refer to README to more information.
For Mandriva Cooker ( development ) users, 4.3.0 is will be available at cooker repositories.

openSUSE packages are available for openSUSE 11.1 (one-click install), for openSUSE 11.0 (one-click install) and for openSUSE 10.3 (one-click install) and openSUSE Factory (one-click install). A KDE Four Live CD with these packages is also available.

Magic Linux KDE 4.3.0 packages are available for Magic Linux 2.5. See the release notes for detailed information and the FTP tree for packages.

SD card lock switch causing problems

Yesterday while working i needed to tranfer some file to a sd card. This is a simple task, trivial thing to do but i was having trouble doing it. My card reader refused to read my SD card, no matter what i did, started looking at logs, dmesg and so on. after a while without significant info found i tried the card on a friends lap and it worked without a itch.

The only thing that showed up in var log messages was:

Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Unhandled sense code
Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE
Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Sense Key : Medium Error [current]
Jun 23 19:17:43 martini-lap kernel: sd 7:0:0:0: [sdb] Add. Sense: Unrecovered read error
Jun 23 19:17:43 martini-lap kernel: end_request: I/O error, dev sdb, sector 0
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 0
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 1
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 2
Jun 23 19:17:43 martini-lap kernel: Buffer I/O error on device sdb, logical block 3

well the prob was the tiny switch on the SD card that allows you to lock on read only mode. The card was lacking the switch, with some adesive tape it was fixed. The strange thing is that it worked on my friends lap. Maybe it’s lap doesn’t check for the lock switch.

Hope this may help someone out there with the same prob.

Cheers.

Pedro