Uninstall flatpak

1. sudo apt install flatpak 

2. flatpak uninstall --all 

3. sudo apt purge --autoremove flatpak

4. Check directory /var/lib/flatpak should be everything removed.

Ubuntu 20.04 problem with headphone?

 

Step 1. pulseaudio --kill
Step 2. pulseaudio --start
Step 3. Settings->Sound->Output devices->Headphones

How to burn a Windows .iso to a USB device in Ubuntu?

 Step 1.   Download Windows10

https://www.microsoft.com/pl-pl/software-download/windows10ISO

Step 2.   Check where is mounted your usb stick.

sudo    fdisk -l

Step 3. Run command:

sudo dd bs=4M if=[path to windows iso] of=/dev/sd[that 1 letter]

Securely erasing storage device

 Shred - overwrite data on a whole device with random bits.

1. Identify the name of the device

        fdisk -l     

 

Disk /dev/sdc: 931,53 GiB, 1000204886016 bytes, 1953525168 sectors
Disk model: SAMSUNG HD103SJ
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes 

 

2.  Execute command::

                 

    sudo shred -v -n1 -z /dev/sdX

 

    -v flag is verbose and will print  the current progress

    -n1 overwrite blocks on the device "n1" times

    -z set all bits to zero after the last iteration

 

 

 ....

shred: /dev/sdc: pass 2/2 (000000)...920GiB/932GiB 98%
shred: /dev/sdc: pass 2/2 (000000)...921GiB/932GiB 98%
shred: /dev/sdc: pass 2/2 (000000)...922GiB/932GiB 98%
shred: /dev/sdc: pass 2/2 (000000)...923GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...924GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...925GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...926GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...927GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...928GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...929GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...930GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...931GiB/932GiB 99%
shred: /dev/sdc: pass 2/2 (000000)...932GiB/932GiB 100%

Install Unity in Ubuntu Server

1. sudo apt install ubuntu-unity-desktop
2. reboot machine

How convert mkv to mp4

•  convert an input video file into a MKV file using VP8 encoding with VORBIS audio encoding

           ffmpeg -i input_video.avi -f matroska -vcodec vp8 -acodec libvorbis output_video.mkv

• convert a video into a video using VP9 for video encoding and OPUS as audio encoding

           ffmpeg -i input_video.avi -f matroska -vcodec vp8 -acodec aac output_video.mkv

How enable ssh on ubuntu

To enable SSH:

sudo apt-get install openssh-server
After instalation the SSH service should be started automatically. You can start, stop or restart the service manually:

sudo service ssh start              (stop|restart)
To edit settings:

To change the port, root login permission, you have to edit the /etc/ssh/sshd_config file via:

sudo nano /etc/ssh/sshd_config

Remove # from the line 13.
9 # OpenSSH is to specify options with their default value where
10 # possible, but leave them commented.  Uncommented options override the
11 # default value.
12 
13 Port 22
14 #AddressFamily any
15 #ListenAddress 0.0.0.0
16 #ListenAddress ::