Aug 232014
 

KernelPanic Luckily this problem don’t happen so frequently, at least using stable kernel and distributions, but sometime your beloved Linux could go in “Kernel Panic”.

A kernel panic is an action taken by an operating system upon detecting an internal fatal error from which it cannot safely recover. The term is largely specific to Unix and Unix-like systems; for Microsoft Windows operating systems the equivalent term is “stop error” (or, colloquially BSOD “Blue Screen of Death”).

The kernel routines that handle panics, known as panic() in AT&T-derived and BSD Unix source code, are generally designed to output an error message to the console, dump an image of kernel memory to disk for post-mortem debugging and then either wait for the system to be manually rebooted, or initiate an automatic reboot.

Wikipedia

The default it’s to wait, so if this happen on one of your servers and you don’t notice it all its services could stay down for some time, while using an automatic reboot the problem could be solved quickly.

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Aug 192014
 


What’s your upload and download speed at home (or in your office) ?
Are you really sure that you get what do you pay for to your ISP ?

To test the speed of our internet connection There are several internet services such as SpeedTest a web service that is available both from Web browsers and mobile application.

Now you can easily check it also with speedtest_cli a command line interface for testing internet bandwidth using speedtest.net. In this way you can do the test also on servers that don’t have a Browser or a graphical interface. Continue reading »

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Aug 132014
 

Article by giannis_tsakiris first posted on http://www.giannistsakiris.com

A hard link is actually nothing more than a regular directory entry, which in turn can be seen as a pointer to the actual file’s data on the disk. The cool thing about hard-links is that a file can be stored once on the disk, and be linked to multiple times, from different locations/entries, without requiring to allocate extra disk space for each file instance.

But then a question arises: Given a specific file on disk, how can someone know whether it is linked to by other directory entries or not? This can be easily answered using the ls command:

giannis@zandloper:/etc$ ls -l passwd
-rw-r--r-- 1 root root 1402 2008-03-30 17:49 passwd
;

Do you ever wonder what is this small number between the file permissions and the owner in the output of ls’s long listing format (its value is usually “1″ for files, or “2″ for directories)? This number is actually the link-count of the file, when referring to a file, or the number of contained directory entries, when referring to a directory (including the . and .. entries).
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Aug 092014
 

In previous posts we’ve seen how to Enable automatic security update in Debian/Ubuntu and in Red hat enterprise or Centos 6, recently I’ve started to work with the new Red Hat Enterprise 7 and I’ve noticed that there are some interesting changes in the way this system can be set to auto update.

An example ?

In Red Hat/Centos 6 you could not set which kind of update you’d like to do, so you could just decide to update for any kind of update (feature,bug or security) or nothing at all, this has changed and now we can fine grain which kind of updates we want to do on our servers.

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Aug 012014
 

If, like me, you work on terminals connected via ssh to remote computer/server you are probably used to tmux and screen and so it’s not a problem if you have to close your session, as you’ll be able to easily re-connect when you need it, but sometimes you could forget about using one of these utility.

Started a long-running process over ssh, but have to leave and don’t want to interrupt it?
Just start a screen, use reptyr to grab it, and then kill the ssh session and head on home.

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