Disable VirtualBox clock synchronization

For whatever reason you may want to disable the time/date synchronization between the VirtualBox guest system and the host OS.

See the example below to do that for an example virtual machine “myName”:

  • vmname=”myName”; printf “Disabling clock sync for vm: \”$vmname\”\n”; VBoxManage setextradata $vmname “VBoxInternal/Devices/VMMDev/0/Config/GetHostTimeDisabled” 1; VBoxManage setextradata $vmname “VBoxInternal/TM/TSCTiedToExecution” 1;

Unfortunately this is ignored when the virtual machine is shut down and then started again. The clock of the virtual machine will be forcefully synchronized to the host system clock. If you know a workaround, please post it in comments.

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Input line is too long

So you create a .bat file with a long list of arguments and it fails with a message:

“the input line is too long”

To avoid this, split your long single line into multitude of shorter lines separated by the caret character to mark the line break. Like this:

echo 1^
 2^
 3

 


Error – getcwd failed!

You run a command on command line and receive a mysterious error message:

sh: 0: getcwd() failed: No such file or directory

Possible explanation is that the directory you were working in has been deleted by some other process and indeed just does not exist anymore. Move, for example by typing “cd”, and continue working elsewhere.


Invalid command RewriteEngine

After (re-)installation of Apache2 the browser greets you with error 500 “Internal Server Error” and Apache2 error log file contains message “Invalid command ‘RewriteEngine’, perhaps misspelled or defined by a module not included in the server configuration”.

Well, you might want to enable mod_rewrite, which is disabled by default:

  • a2enmod rewrite
  • service apache2 restart

Missing php-mbstring

After (re-)installing PHP and attempting to run a script, you may see an error message saying “PHP Fatal error: Uncaught Error: Call to undefined function mb_strtoupper()”.

Well, you may be missing the php-mbstring extension to PHP. Simply install it by:

  • sudo apt-get install php-mbstring

Symbolic links in Nautilus/Caja

It is very irritating that there seems not to be an option for creating links to files in Gnome file manager Nautilus and its derivatives, like Caja. After all, this is such a useful feature, giving the user so much more convenience when working in Linux as compared to Windows.

It turns out, that the feature is actually there, but for some weird reason it is not available from the GUI.

Just press Ctrl+Shift and drag and drop your file between file manager’s windows, and a symbolic link will be created instead of copying the file.

As an alternative, you can do the dragging with the middle mouse button. Then on drop you will be shown a context menu with “Link Here” as an option.
 


Is my system 32 or 64 bit?

On Linux, to find out if you have 32 or 64 bit CPU just type:

  • arch