vim – Unable to paste with middle mouse button – E353: Nothing in register ” error – Solution

Put set clipboard=unnamed within your ~/.vimrc VIM configuration file.

Re-posted from

Obscure error: dd: failed to open: No medium found

I got this error message when I wanted to use dd  to copy a raw image to a MicroSD card. You will see this message if you have unmounted the card with a file manager like Nautilus. I guess it unmounts not fully, or in a special way.

The fix is easy:

Unmount the card via the terminal:

The dd  command will work now.

Another variant of this error can be seen when using bmaptool :

Symlinks within shared folders in VirtualBox: Operation not permitted and Read Only Filesystem

This is not a bug, it is a security feature of Virtual Box. Nevertheless it is annoying when you want to use your virutal system as a build system which needs symlinks in shared folders. To enable symlink creation, do the following:

Shut down your virtual machine, close all VirtualBox windows, including the main GUI window

For example, if your virtual machine is called “Debian Wheezy” (with a space), you have to escape that space with a backslash. In my case, I had to do:

To check if your setting has been taken, run

Restart your virtual machine and creating of symlinks should work. I found that creating hard links still doesn’t work with this method. If anyone knows a fix for hard links, please let me know!

A solution for MySQL Assertion failure FIL_NULL

Mysql screenshot

A defective RAM module recently caused data corruption in MySQL tables. MySQL would log the following to /var/log/syslog  in regular intervals, about every few minutes:

Reading MySQL documentation and various blogs didn’t help much. I ran CHECK TABLES  on all the tables and they all reported OK. Then I ran

and still all tables reported OK. Nevertheless the Assertion Failures continued. Then I stumbled across this excellent blog post, which suggested to dump evertying into a .sql file, wipe /var/lib/mysql (not without making a backup, mind you!), and re-import everything from scratch. This is what I did and it worked.

I recorded the passwords for each database and collected it into a SQL script like this:

When you dump all databases into a .sql file, it will not dump the permissions, so you will need to restore them later with this script. Next, the dumping part, then removal and reinstallation of mysql (Danger here: When you remove mysql-server, all packges which depend on it also will be removed!):

Here, I had to reset the MySQL admin password because it didn’t work any more, so I ran:

Then, I re-imported all databases from the dump file:

Then I run the SQL permission script that I mention above.

For me, this resulted in no more Assertion Failures. Yay!



Adventures with various Segfaults due to defective RAM


If you get various segfaults on your Linux server, like these:




etc. etc., then, no, your system is not suddenly crazy. Nor are you. It is highly likely that you RAM is defective. You should reboot your server and run the  RAM test from your boot manager (Grub always has such a test) to see if it can detect faulty RAM.

If you are operating a server that you can’t reboot because you can’t tolerate downtime, there is an excellent tool called memtester , which is a memory test for a running system. It is part of the Debian distribution, installit with apt-get install memtester  Check top to see how much free RAM there is available. Say you have 10GB RAM free, then ask memterst to test 8GB of it (so that 2GB are remaining free for the running system to operate). In my case, memtester indeed detected faults.

I ran

It outputted stuff like this:

So, when I replaced the RAM, the Segfaults stopped. You can run memtester  regularly to make sure the RAM is okay. Healty RAM is a very crucial part of your successful hosting operation!

In my case however, the segfaults corrupted MySQL tables, which I had to clean up. All’s well that ends well!