Useful Ubuntu Commands

For my own use, I’ve just started collecting various Ubuntu commands and tips on this page – saves me searching every time. I’ll add to it as I go. I hope you may find it useful too. After each command I will link to more information. Please view the links before executing potentially dangerous commands like ntfsfix. I’ll prefix the title of such commands with a (WARN).

(WARN) Let Nautilus Run an Executable Text File

By default, if you double-click on an executable text file Nautilus will open it in the default application. To execute the file instead, in the Nautilus Settings (click on the Hamburger Menu), look for this option:

Preferences -> Behavior -> Executable Text Files

and check the option Run Them.

warning: be careful which file you execute.

Improve Gnome Performance

Ubuntu 19.04 felt a bit laggy for me, telling the power system to use performance mode improved it. Note: On a laptop this will drain battery fast.

To inspect the value of this variable for each core:

cat  /sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference

To set it to performance:

echo performance | sudo tee  /sys/devices/system/cpu/cpufreq/policy*/energy_performance_preference

(WARN) Mounting an NTFS parition which didn’t shutdown cleanly.

My laptop shutdown suddenly and refused to boot anymore. The SSD couldn’t mount from an external drive because the NTFS partition wasn’t shutdown cleanly. The solution:

sudo ntfsfix /dev/sdb2

For more information, see here.

Increasing or decreasing the volume of a video using FFMPEG

ffmpeg -i input.wav -af 'volume=2' output.wav

Replace volume=X with a suitable number. For example 0.5 will half, 2 will double the volume. For more information see here and here.

Mounting a USB Device in Virtual Box

After installing VirtualBox I was unable to connect to any USB Devices from within my virtual machine. The solution was to add my user to the vboxusers group:

sudo usermod -a -G vboxusers $USER

You’ll need to log out and back in to effect the change. See here for more information.

Finding a Missing Shared Library

I like to use Clipgrab on KDE Neon, but when I try to run it, I get the following error:

error while loading shared libraries:

The solution is to use apt-file to identify the package which provides this shared library, and then install it:

apt-file search
sudo apt install libqtwebkit4

See here for more information.

Wierd mouse in KDE

Change the “System setting -> Display and Monitor -> Compositor -> Rendering Backend” from openGL 2.0 to XRender.

see here

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