Nov 182013
 

Original article first published in Spanish on http://vidagnu.blogspot.it/

Yesterday I ran into a problem in a SWAP partition on an Astaro Command Center, so I decided to restart with an Ubuntu CD, and my first attempt to repair the system was with the fsck command, but when trying to use it I got the message fsck.swap: command not found

So I check with the badblocks command that the partition had no bad blocks.

sudo badblocks -v /dev/sda2

The above command did not return any error, then searching the Internet I found this simple way to rebuild a damaged swap partition.

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Nov 122013
 

Article by David Rhys Forward, first publish on Full Circle Magazine #77

Faster Than Light (more commonly known as FTL) is a top-down, real-time strategy game on Steam, made by indie team Subset Games. The player takes control of the crew in a space vessel that’s in possession of critical information that must be delivered to an allied fleet several sectors away. However, to make the game more challenging, you are pursued by a large rebel fleet in every sector.

In keeping the story simple, the team has been able to create an indepth management system. You must maintain the ship when it’s damaged and make difficult decisions when under attack. For example, jumping in the middle of battle or taking energy from one source to power a weapon.
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Oct 202013
 

As system administrator, or simple user that uses Linux on its desktop sometime you notice that something it’s eating all the memory of your system.
As first thing be sure to understand how Linux manage memory, I’ve be called too many time by scared users that did a free and were unable to read its output properly, in short, don’t worry if the Linux Kernel it’s using your memory to cache file.

< rant on >

To my “beloved” users:

Be assured that the Kernel developers can do a better job than you (and me) in find a good algorithm to cache file and free that memory area when a process need it, so please don’t ask me to put in cron some job that run something like that :

echo 3 > /proc/sys/vm/drop_caches

After that you’ll have more free memory available on the system, true, but the system will have to re-read all the files from the disk, so in terms of performance this is usually a bad move.

< /rant >

But now let’s take a look at a nice small program that can help us in find which process/users are using, for real, the memory of our systems.

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Oct 122013
 

Sometimes a program or software don’t start for a syntax error, and if you check the files there is nothing wrong..apparently.
There are a lot of characters that usually are not printed if you use a normal text editor, but you can easily check if they are present with your terminal and the command cat.

As first thing let’s create a simple text file with these special characters, open a terminal and run the command:

printf 'testing\012\011\011testing\014\010\012more testing\012\011\000\013\000even more testing\012\011\011\011\012' > /tmp/testing.txt

Now if you open the file with an editor you’ll have different results.
A simple cat will show:

$ cat /tmp/testing.txt 
testing
		testing
 
more testing
 
        even more testing

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