How to Get a list of Installed ‘web-apps’ and Remove them in Ubuntu 12.10?

Although it is very tempting, due to few reasons, I have decided to wait a few more months (hopefully) before I give a go at the new Ubuntu Unity’s ‘web-apps’ features. Now I did install few of these apps, but I had few glitches here and there and it doesn’t seem like the ‘web-apps’ feature is quite there yet (at least in my ‘short’ experience).

Anyhow, whether you use this feature or not, if you have installed some of these ‘web-apps’ through Firefox, then it can be a bit difficult to get rid of them later, as there is no way to get a list of currently installed ‘web-apps’ through the ‘Online Accounts’ tool (it does not show all the installed apps).
But luckily, you can use a simple trick in the Terminal window, to get a list of currently installed ‘web-apps’. And once it gives you the list, then you can use the usual ‘apt-get remove …’ command to get rid of them easily.
For that, please follow the below steps.
Step 1: Finding them.
Open your Terminal window and enter the below command.

dpkg --get-selections |grep unity-webapps

This as shown below, should give you a list of currently installed ‘web-apps’.

Note: ‘libunity-webapps0′ and ‘unity-webapps-service’ are core libraries of ‘web-apps’. So make sure not to remove them.
Step 2: Removing them.
Let’s say I wanted to get rid of the ‘Launchpad’ web-app, then I’ll use the below command.

sudo apt-get autoremove unity-webapps-launchpad

You can remove multiple ‘web-apps’ at the same time too. For that, make sure to add a ‘space’ between each package’s name, as shown below.

sudo apt-get autoremove unity-webapps-launchpad unity-webapps-youtube

Also remember to replace these package names with the ones installed on your Ubuntu OS (of course). That’s it.

Slax 7.0 Preview

Tomáš Matějíček has announced the availability of a public preview release of Slax 7.0, a Slackware-based live CD with KDE 4 in under 180 MB: "So here it is. A small lightweight KDE, recompiled with as few dependencies as possible. I've partially completed my battle with the KDE desktop environment. There is a lot of work waiting in the queue, since there are no applications yet except Konsole; however, it is ready for wider public testing. I am convinced it was worth the effort. Both 32-bit and 64-bit variants are ready for testing. I've configured four workspaces. Try to switch between them using your mouse - simply move your mouse pointer to the very top left of the screen. No clicking needed. You should see the effect." Here is the full release announcement with screenshots. Download (MD5): slax-7.0-kde4-2012-10-20-i486.iso (177MB), slax-7.0-kde4-2012-10-20-x86_64.iso (183MB).

Ubuntu Builder 2.3.0 Adds Support For Ubuntu 12.10 Quantal Quetzal

Ubuntu Builder has been updated to version 2.3.0 recently which adds support for Ubuntu 12.10 Quantal Quetzal and at the same time drops support for Natty. Ubuntu Builder is a tool with GUI that allows users to build a customized version of their Ubuntu-based distributions. The tool allows to customize either i386 or amd64 OS images.

 Here are some of the changes in this latest release:

· Added Quantal Quetzal support. 

· Removed Natty Narwhal support. 

. Bugfix: I get '/casper/vmlinuz not found' with customized kernel image. 

· Bugfix: Lack of kernel when the kernel is updated. 

· Improved log generation. 

· User manual updated. 

· Now depends on gambas3-gb-image (only Gambas 3 version).

Ubuntu Builder Installation

Open the terminal and install Ubuntu Builder 2.3.0 in Ubuntu 12.10/12.04 or Linux Mint 13 with the following commands:

sudo add-apt-repository ppa:f-muriana/ubuntu-builder
sudo apt-get update
sudo apt-get install ubuntu-builder 

For any bug encountered, you can report it here.

Install VirtualBox 4.2.2 In Ubuntu 12.10 (Quantal Quetzal) and Linux Mint 13

 VirtualBox for Linux has just been updated to version 4.2.2. This is a maintenance release that brings full support to X.Org Server 1.13 and Linux Kernel 3.7 RC1. Here are some of the key changes in this latest release:

• Linux hosts / guests: Linux 3.7-rc1 fixes

• Linux Additions: support X.Org Server 1.13

• Linux Additions: fixed a hang when the X server was restarted with old guest kernels

• Linux Additions: fixed a VBoxService crash during CPU hot remove

You can find the full changelog of VirtualBox 4.2.2 here.

VirtualBox 4.2.2 Installation

If you have an older version (4.1, 4.0, 3.2, 3.1, etc.) of VirtualBox, it is recommended that you uninstall it with these commands:

 sudo apt-get purge virtualbox-4.1

To install VirtualBox 4.2.2 in Ubuntu 12.10/12.04 or Linux Mint 13, open the terminal and issue these commands:

echo "deb http://download.virtualbox.org/virtualbox/debian $(lsb_release -sc) contrib" | sudo tee /etc/apt/sources.list.d/virtualbox.list

wget -q http://download.virtualbox.org/virtualbox/debian/oracle_vbox.asc -O- | sudo apt-key add -

sudo apt-get update

sudo apt-get install dkms virtualbox-4.2

Troubleshooting

For users having problems enabling "Guest Additions" with Ubuntu 12.10 running as guest OS, you can simply install these packages manually via the terminal:

sudo apt-get install virtualbox-guest-additions

sudo apt-get install virtualbox-guest-dkms virtualbox-guest-x11 virtualbox-guest-utils

When you finish, reboot the VM (virtual machine). The screen resolution of Ubuntu 12.10 will now change when resizing the VM. Also, open Devices > Shared Clipboard and enable the "Bidirectional" option:

GhostBSD 3.0-RC2

Eric Turgeon has announced the availability of the second release candidate for GhostBSD 3.0, a desktop-oriented operating system with GNOME or LXDE based on FreeBSD: "The second release candidate of GhostBSD 3.0 GNOME 2 and LXDE is now available for testing. Changes since LXDE RC1: FreeBSD 9.1-RC1 to FreeBSD 9.1-RC2; new WiFi configuration method; Firefox has replaced SeaMonkey; we have ported LXMusic to FreeBSD to replace Audacious; we have ported LxRandr to FreeBSD and add it; XChat has been added; X.Org is now automatically configured; Slim has been replace by GDM." See the release announcement for more details and known issues. Download: GhostBSD-3.0-RC2-gnome2-i386.iso (969MB, MD5), GhostBSD-3.0-RC2-lxde-i386.iso (628MB, MD5), GhostBSD-3.0-RC2-gnome2-amd64.iso (1,018MB, MD5), GhostBSD-3.0-RC2-lxde-amd64.iso (680MB, MD5).

Some Useful FFMPEG Commands (Screencasting, Rotate Video, Add Logo, etc.) - Ubuntu/Linux Mint

In this tutorial we will see some useful FFMPEG commands that you can use on Ubuntu/Linux Mint to make screencasting videos, rotate videos, add logo/text watermarks to a video, insert shapes, and so on.

To install ffmpeg and some other packages on Ubuntu/Linux Mint, open the terminal and run these commands:

sudo apt-get install ubuntu-restricted-extras

sudo apt-get install ffmpeg x264

sudo apt-get install frei0r-plugins mjpegtools

Note: The file formats used in this tutorial are selected randomly and you can set any other extension of your choice.

1. Screecasting

To record your screen withh FFMPEG, you can use this command:

ffmpeg -f x11grab -follow_mouse 100 -r 25 -s vga -i :0.0 filename.avi

Now the command will record every spot on your screen you hover your mouse cursor over. Press Ctrl+C to stop recording. If you want to set a screen resolution for the video to be recorded, you can use this ffmpeg command:

ffmpeg -f x11grab -s 800x600 -r 25 -i :0.0 -qscale 5 filename.avi

To show the region that will be recorded while moving your mouse pointer, use this command:

ffmpeg -f x11grab -follow_mouse centered -show_region 1 -r 25 -s vga -i :0.0 filename.avi

If you want to record in fullscreen with better video quality (HD), you can use this command:

ffmpeg -f x11grab -s wxga -r 25 -i :0.0 -sameq  video.mp4

Her is a video example created with the latter command:

2. Add Audio To A Static Picture

If you want to add music to a static picture with ffmpeg, run this command from the terminal:

ffmpeg -i audio.mp3 -loop_input -f image2 -i file.jpg -t 188 output.mp4

3. Add Image Watermarks to A Video

To add an image to a video using ffmpeg, you can use one of these commands:

Picture Location: Top Left Corner

ffmpeg -i input.avi -vf "movie=file.png [watermark]; [in][watermark] overlay=10:10 [out]" output.flv

Here is an example:

Picture Location: Top Right Corner

ffmpeg –i input.avi -vf "movie=watermarklogo.png [watermark]; [in][watermark] overlay=main_w-overlay_w-10:10 [out]" output.flv

Picture Location: Bottom Left Corner

ffmpeg –i input.avi -vf "movie=watermarklogo.png [watermark]; [in][watermark] overlay=10:main_h-overlay_h-10 [out]" output.flv

Picture Location: Bottom Right Corner

ffmpeg –i input.avi -vf "movie=watermarklogo.png [watermark]; [in][watermark] overlay=main_w-overlay_w-10:main_h-overlay_h-10 [out]" output.flv

4. Add Text Watermarks To Videos

To add text to a video, use this command:

ffmpeg -i input.mp4 -vf drawtext="fontfile=/usr/share/fonts/truetype/freefont/FreeSans.ttf: text='YOUR TEXT HERE':fontcolor=red@1.0:fontsize=70:x=00: y=40" -y output.mp4

An example:

To use another text font, you can list them from the terminal with this command:

ls /usr/share/fonts/truetype/freefont/

4. Rotate Videos

To rotate a video 90 degrees with ffmpeg, run this command:

ffmpeg -i input.avi -vf transpose=1 output.avi

Here is an example for a video rotated with ffmpeg:

Here is all parameters:

• 0 = 90 degrees CounterCLockwise  (Vertical Flip (default))
• 1 = 90 degrees Clockwise
• 2 = 90 degrees CounterClockwise
• 3 = 90 degrees Clockwise (Vertical Flip)

5. Adjust Audio/Video Volume
You can use ffmpeg to change volume of a video file with this command:

ffmpeg -i input.avi -vol 100  output.avi

To change volume of an audio file, run this command:

ffmpeg -i input.mp3 -vol 100 -ab 128 output.mp3

6. Insert A Video Inside Another Video

To do this, run this command:

ffmpeg -i video1.mp4 -vf "movie=video2.mp4:seek_point=5, scale=200:-1, setpts=PTS-STARTPTS [movie]; [in] setpts=PTS-STARTPTS, [movie] overlay=270:240 [out]" output.mp4

Here is an example:

7. Add a Rectangle To A Video

To draw for example an orange rectangle in a video, you can use this command:

ffmpeg -i input.avi -vf "drawbox=500:150:600:400:orange@0.9" -sameq -y output.avi

Video example:

If you have something to add or report a mistake, please use the comment form below.