Note: This solution only works with the cfq scheduler, as explained here. You should check which one is used by issuing

cat /sys/block/sda/queue/scheduler

and change it if necessary.

If I understood correctly, you want some ionice setting to be applied every time you start a command. You can do it this way:

echo 'ionice -c 3 /usr/bin/VirtualBox "$@"' > VirtualBox

chmod a+x VirtualBox

sudo mv VirtualBox /usr/local/bin/

First command creates a file VirtualBox with the single-quoted text as its content. This should have the full path to the program, because if one only specify VirtualBox it can interpret it as the file we just created and create a "loop".

Second command makes it executable, and third moves this new file in a folder which is in front of the "system" bin folder /usr/bin, so our new file gets executed instead of the original. The "$@" part contains all the arguments the command was invoked with, so they get forwarded to the real VirtualBox command.

According to answer ("yes") to this Super User question Do children processes inherit ionice priorities from their parents? How do you check the IO priority of a running process?, it should be enough to ionice the parent process, like this:

ionice -c 3 VirtualBox

From ionice man page, following I/O scheduling class values are available:

• 0 for none


• 1 for realtime


• 2 for best-effort


• 3 for idle (used in example above)

A number or class name can be used.

Also, -n level option is applicable for realtime and best-effort classes, with 0-7 as valid data (priority levels).