Edit: Oh sorry, didn't read carefully. I was thinking of the normal Ubuntu.
Most of the steps should apply though, as Unity is based on GNOME 3.

How To Install XFCE alongside Unity (the enviornment that comes with Ubuntu)

It's recommended to add another user so data doesn't corrupt. (Skip if you don't want to)

Open System Settings (unity-control-center) and click User Accounts. Click the Unlock button on the top right and type in your password as needed. Then, click the + button on the bottom left and select Administrator. Then, choose a Username and Name for the account.

Log out of the account you are in right now and Log In to the account you just made.

Install XFCE

It's recommended to update your sources.
Open Terminal with Ctrl + Alt + T and type

sudo apt-get update

Then, install XFCE!

sudo apt-get install -y xfce4 xfce4-goodies

Log out, click the Ubuntu logo over the account name, and click XFCE.

Another way

You can download Xubuntu from the official website, here

Hope this helped!


Asus 1201n will not sleep with Kubuntu 12.04

I own an asus n55, this problem seems to plague many asus models, and i think yours might be having the same problem.
heres the link to the solution, use the 1st script in the step2

http://thecodecentral.com/2011/01/18/fix-ubuntu-10-10-suspendhibernate-not-working-bug


Unable to start KODI / XBMC from the dash in ubuntu 14.04

Due note that this might just be a bug with the new release. Maybe the developers forgot to make the .desktop file? :P

Purge it like so:

sudo apt-get purge xbmc kodi

Remove dependencies:

sudo apt-get autoremove

And reinstall:

sudo apt-get install kodi


USB Mouse and Keyboard stop working unexpectedly

My experience, for what it is worth.

I had a similar problem with a Dell e6420 laptop, purchased used with Windows 7, and Ubuntu 14.04 added after the fact by me. The touchpad was turned off, and a Logitech wireless mouse with 'Unifying receiver' used. The primary application is as a Minecraft gaming machine.

After apparently random periods of time these symptoms would appear: the mouse pointer would move, but the mouse buttons and keyboard enter key would stop working. The only consistent work-around I found was a power reset. The quite extensive embedded Dell diagnostics reported no hardware issues.

I noticed that these symptoms primarily occurred with a userid set up with restrictive permissions, and configured to auto-login on boot. Using the "Users and Groups" administrative application (sudo apt-get install gnome-system-tools) I selected the offending account, hit the "Advanced" button, selected the "Permissions" tab and ensured that all check boxes were ticked (In my case, I added ticks to the only three that were not previously selected: tape drives, floppy drives and send and receive faxes. To my mind, the three have no apparent link to mice or keyboards).

With this as the only change, after a reboot the symptoms disappeared.


You could also simply run nautilus -q from the command line.


Nvidia 7800 gtx (drivers not working for 12.04)

Remove the existing driver
Codes:
sudo apt-get update
sudo apt-get purge nvidia-current
sudo apt-get purge nvidia-current-updates

Installing NVIDIA driver
Codes:
sudo apt-add-repository ppa:ubuntu-x-swat/x-updates
sudo apt-get update
sudo apt-get install nvidia-current

Then restart the computer and do this:
Code:
nvidia x server settings

If "nvidia: command not found"

Try Code:
nvidia-settings

Done!


Ubuntu 17.04 (Zesty) uses systemd. See this link so you should use the systemctl command. Ubuntu has been using systemd for a while now.


If possible upgrade to 19.10 and you would have 1.2.10

  Package fwupd

bionic (18.04LTS) (admin): Firmware update daemon    1.0.6-2ubuntu1
eoan (19.10) (admin): Firmware update daemon    1.2.10-1ubuntu2

In case that is not an option you could try to install the debian install file from 19.10 either manually through dpkg or the software center and then pick all the dependencies needed as instructed during the attempt to install. The list of requirements is pretty long.

Next best thing is to install it from source and use that version.

Main components of the compilation instructions:

# apt build-dep fwupd
# meson build

I don't believe it to be a good idea to do this other then from a newer version of Ubuntu. We are talking about updating device drivers. Those are also connected to the kernel so upgrading from within 18.04 might have you end up installing things from 19.10 anyways.


Change mount point to / and install boot loader to /dev/sda. It will work, carry on.


How do I get a specific file from the kernel's source code?

Obtaining Linux's Sources (For Ubuntu's Downstream Kernel)
You obtained the kernel sources somehow. You should redownload them, or redo whatever you did to get them.
In particular, if you're running Ubuntu 12.04, and either you don't know how you got your kernel sources or you got them by installing a package whose name starts with linux-source, then you can put back any deleted file by completely reinstalling the package:
sudo rm -rf /usr/src/linux-source-3.2.0/linux-source-3.2.0
sudo apt-get update
sudo apt-get --reinstall install linux-source-3.2.0
cd /usr/src/linux-source-3.2.0
sudo tar xvjf linux-source-3.2.0.tar.bz2

(Please note that it is intentional that linux-source-3.2.0 appears twice in the first command, which removes the manually extracted source directory, if any.)

You might also want to have the package linux-source (with no version number in the name) installed, so that you keep getting the source code for new kernels as they become available. But reinstalling linux-source with the above method will not replace missing files, as linux-source is just a metapackage that always depends on the most recent versioned linux-source- package in your Ubuntu release.

Searching For Files By Name In Kernel Sources
Now you should have the missing files, so search for them:
find /usr/src/linux-source-3.2.0/linux-source-3.2.0 -iname Option.c -or -iname usb-wwan.h

Please note that I've used the -iname option, which performs case-insensitive matching. (Option.c, with a capital O, is a somewhat unlikely name for a source file in the Linux kernel's sources.)
The output will look like:
/usr/src/linux-source-3.2.0/linux-source-3.2.0/drivers/usb/serial/option.c
/usr/src/linux-source-3.2.0/linux-source-3.2.0/drivers/usb/serial/usb-wwan.h

Please note that these files are from Ubuntu's downstream kernel, patched (i.e., modified) specially for Ubuntu, and its parent distribution, Debian. See this page (especially this section) for details. This is probably what you want, because it corresponds to the kernel that's likely to actually be installed on your machine. But depending on your specific needs, you might need a different kernel altogether.


Playing different music at different channels

You can use pavucontrol to achieve this. Simply start two applications which are capable of play music and than inside pavucontrol click on the lock to control the left and right channel. Mute the left channel for the first application and the right for the second application and you are done.


What is the "path to ant" that Crosswalk speak of?

In general, the evironment variable $PATH specifies the directories in which to look when executing a command. From the official manual:

  When you type a command to run, the system looks for it in the directories specified by PATH in the order specified

You can add directories to $PATH with export PATH="/path/to/executable":$PATH. Note that the : serves as separator between directories and you should only specify the path to the directory which contains the executable file and not the file itself.

In your case you can skip this step, as java and ant are already found.


Permission denied viewing content of remote network share

Your dir_mode is 711. It's rwxr--r--. Directories need to be executable. Try changing it to 755.

And set your .utascredential file to: -rwxr-xr-x


Which is the right way to drop caches in Lubuntu?

Finally I found something that works...

sync

sudo sh -c "echo 1 > /proc/sys/vm/drop_caches"

sync

sudo sh -c "echo 2 > /proc/sys/vm/drop_caches"

sync

sudo sh -c "echo 3 > /proc/sys/vm/drop_caches"

And if you want to drop thumbnails make this:

rm -v -f ~/.cache/thumbnails/*/*.png ~/.thumbnails/*/*.png

 rm -v -f ~/.cache/thumbnails/*/*/*.png ~/.thumbnails/*/*/*.png

Of course you should use:

sudo apt clean
sudo apt autoclean

And that would be all...
At least I thought so... but I may be wrong...


How to restore my Firebird database and modify owner settings in a single command line?

After referring to

Which one is better: using ; or && to execute multiple commands in one line?

I added: && sudo chown firebird:firebird /database/<database name>.fdb to my command to form:

zcat /var/www/temp/<database name><backup timestamp>.gbak.gz | gbak -rep -v stdin /database/<database name>.fdb -user <username> -pass <password> && sudo chown firebird:firebird /database/<database name>.fdb

This successfully changed the ownership settings in one line.

If there is a better practice I am happy to here it and why.


If you use list view,you can see the original location.


How do I create a persistent Fedora live usb

Ubuntu comes with default Disk/Usb creator. Search in Unity Startup Disk Creater & after selecting ISO & Drive, select Stored in reserved extra space & give your persistence space

OR ELSE

Use Unetbootin to make Live USB with persistence!


Unfortunately, hibernate doesn't work in many cases, which can cause you to lose data if you expect your documents and applications to re-open when you switch your computer back on. Therefore, hibernate is disabled by default.
Test if hibernate works
Note : Always save your work before hibernating
You should save all of your work before hibernating the computer, just in case something goes wrong and your open applications and documents cannot be recovered when you switch on the computer again.
You can use the command line to test if hibernate works on your computer.

Open the Terminal by pressing
Ctrl+Alt+T or by searching for
terminal in the Dash.

Type sudo pm-hibernate into the terminal and press
Enter.Enter your password when prompted.

After you computer turns off, switch it back on. Did your open applications re-open?

If hibernate doesn't work, check if your swap partition is at least as large as your available RAM.
Enable hibernate
If the hibernate test works, you can continue to use the sudo pm-hibernate command when you want to hibernate.
You can also enable the hibernate option in the menus. To do that, use your favorite text editor to create /etc/polkit-1/localauthority/50-local.d/com.ubuntu.enable-hibernate.pkla. Add the following to the file and save:
[Re-enable hibernate by default in upower]
Identity=unix-user:*
Action=org.freedesktop.upower.hibernate
ResultActive=yes

[Re-enable hibernate by default in logind]
Identity=unix-user:*
Action=org.freedesktop.login1.hibernate; org.freedesktop.login1.hibernate-multiple-sessions
ResultActive=yes

Restart and hibernation is back!
Or run killall unity-panel-service to just reset the menu.
Some users will then need to run sudo update-grub to get the hibernate option to be available in the power menu. Some users may also have to at least log out then log in to get it to appear in the (upper right) power menu.
Source : Official Documentation


Folder permissions keep reverting back and won't keep changes

You could try serving your files from the /var/www/your-site folder

And then add yourself to the www-data group.

Run this with your user-name

$ sudo usermod -a -G www-data your-user

You should be able to change permissions at will then.

If you want your site files to stay in you home folder you can symlink them to the /var/www/ folder.

How to create a soft or symbolic link?


How to create a standalone bootable Ubuntu USB disk

I think the easiest way is to disconnect (unplug) the internal drive from your computer. Then the installer cannot auto-select the internal drive, which is otherwise a problem in UEFI mode. So you can install 'like you have been doing before' (and this way it should work in UEFI mode too).
An other easy alternative is to start from a compressed image file, that you clone to the USB drive according to the following link,
help.ubuntu.com/community/Installation/UEFI-and-BIOS
This alternative will work also if you are not willing to disconnect the internal drive.


ImportError: cannot import name ForwardHeaderGenerator

Updated, correct answer:
You tried to run the KDSoap package in a wrong way. You were not supposed to run any scripts in the ./autogen/ subdirectory manually, according to the package maintainers, but use the autogen.py file from the project's root directory:

you should be running python autogen.py from the top-level source or from a build dir

Source: GitHub: Comment by the package maintainer
Wrong answer, because of false assumption of package structure:
Open .../autogen/autogen.py with your preferred text editor.
We need to edit two lines.

Search for line 11:
from header import ForwardHeaderGenerator

Replace it with:
import header

Search for line 99:
forwardHeaderGenerator = ForwardHeaderGenerator(

Replace it with:
forwardHeaderGenerator = header.ForwardHeaderGenerator(

Those edits should do the trick. After you confirmed it works I will propose the edits to the GitHub repository.


Ok I found the solution. It is not necessary to use prompt command. The bug arises due to a syntax error.

If I assign the content of PS1 with "" in order to use my variables for the colors, it only executes the __git_ps1 function when .bashrc is sourced.

But when I assign the PS1 content within '' and do it without variables for the color and instead write the codes out, it works as expected. And as I read here it seems to be better practice not to export PS1 to the environment.

So the solution looks like:

PS1='\[\033[01;35m\]\u \[\033[01;32m\]$(__git_ps1 " (%s)") \[\033[01;34m\]\W \[\033[00m\] \$ '

However I would be curious to know, what's the reason for this. It works within "" in macOS.


Have you tried to shut it down from the Terminal?

sudo shutdown -P 1

(Also, try to use some Formatting when Posting here, so your Question is more Readable ;-)


How to resolve unmet dependencies of all applications in Ubuntu 16 version?

Someone maybe able to provide a better answer, but if you still have your original install media, you can reset your OS back to a default state and it should keep all your documents. However, it's never a bad idea to back them up.


What happens to Debian Unstable packages before getting into Ubuntu?

Debian Unstable packages are tested and patched...by Debian volunteers...before going into Unstable.
Ubuntu's policy is to minimize the difference with stock Debian in most circumstances. Some packages carry additional patches, but not many.
Packages are tested for just under 6 months, with lots of bugfixes and patches. (Those bug reports and patches are also forwarded to Debian and to Upstream).
In fact, Ubuntu is just wrapping up one of those cycles now. 20.10 will be released in a couple weeks, after over 5 months of testing and bugfixing.


I thought it was impossible as with UEFI you are supposed to use gpt. But you are using the efi partition on the sda gpt partitioned drive to boot an Ubuntu install on a MBR(msdos) drive.

Better to have sdc as gpt partitioned and include its own efi partition at beginning of drive so it could boot without sda. Some disconnect other drives, other partition in advance & use Something Else and make sure to install grub to correct drive. How you boot installer UEFI or BIOS is how it installs.

Did Boot-Repair convert your BIOS install to UEFI as I did not think installer would create your configuration.

I think some of the issue is the changing from BIOS to UEFI and vice versa. You do have BIOS based boot loaders in MBR.

You may have two entries for ubuntu, one is grub and the other is shim. Shim is for secure boot and grub is for UEFI non-secure boot.

Shows install with screen shots for both BIOS(purple) & UEFI(grub menu), so you know which you are using.

https://help.ubuntu.com/community/UEFI

Also shows Windows 8 screens

Installing Ubuntu Alongside a Pre-Installed Windows with UEFI

"Install alongside" option missing. How do I install Ubuntu beside Windows using "Something Else"?


How should I go about demonstrating Ubuntu on someone else's system?

I would go with Live USB, Ubuntu 12.04 and just let him try it out on a Live USB and then install it.

What was your concern?


You have to forward port 22 of your router to your internal target.


Searching for file contents on whole disk

The likeliest problem is that it will be attempting to enter all the strange files in /sys and /proc and /dev (the first command at least, but /sys will still be an issue). Some of those will be long link chains all of which must be followed and none of which are actually of interest to you.

A much cleaner approach would be to use find and its exec option. Something like:

sudo find / -type f -exec grep -Flm 1 '1.2.3.4' {} +

The above command will find all regular files in / and run grep on them.

The -l means "print the matching file name", which is easier than printing the line and will probably increase your speed as well. Once you have the matching files, you can grep them at your leisure.
The -m 1 means "stop at the first match", this way large files will not need to be processed all the way through to the end if a match has been found.
The + at the end means that find will try and combine this into as few commands as possible (another reason why -l is needed, otherwise you won't know where the file came from). This is documented in man find:

   -exec command ;
          Execute  command;  true  if 0 status is returned.  All following
          arguments to find are taken to be arguments to the command until
          an  argument  consisting of `;' is encountered.  The string `{}'
          is replaced by the current file name being processed  everywhere
          it occurs in the arguments to the command, not just in arguments
          where it is alone, as in some versions of find.  Both  of  these
          constructions might need to be escaped (with a `\') or quoted to
          protect them from expansion by the shell.  See the EXAMPLES sec‐
          tion for examples of the use of the -exec option.  The specified
          command is run once for each matched file.  The command is  exe‐
          cuted  in  the starting directory.   There are unavoidable secu‐
          rity problems surrounding use of the -exec  action;  you  should
          use the -execdir option instead.

   -exec command {} +
          This  variant  of the -exec action runs the specified command on
          the selected files, but the command line is built  by  appending
          each  selected file name at the end; the total number of invoca‐
          tions of the command will  be  much  less  than  the  number  of
          matched  files.   The command line is built in much the same way
          that xargs builds its command lines.  Only one instance of  `{}'
          is  allowed  within the command.  The command is executed in the
          starting directory.

Before running that however, I would recommend you simply run this:

sudo find /etc -type f -exec grep -F '1.2.3.4' {} \;

The chances are ~90% that any configuration file that sets your IP will be in /etc. Specifically, it will probably be /etc/network/interfaces.


System 76 Oryx Pro with Samsung 4k flickering issues

The system76 Oryx Pro notebook ships with the relatively new NVIDIA GTX 9M series.
Generally it is recommended to use the NVIDIA drivers from the Ubuntu repositories.
When you have issues, you can alternatively use the drivers from the GPU Drivers PPA.

So you should try to repair the drivers installation first.

Step 1 : Remove the installed NVIDIA 352 drivers.

Highlight the Ubuntu menu entry and  press the E key.
Add nouveau.modeset=0 to the end of the linux line.
Press the F10 key to boot into the Ubuntu system.

When the login screen appears press Ctrl+Alt+F1.
Enter your user name and password and then execute :

sudo apt-get purge nvidia*
sudo reboot

Step 2 : Re-install the NVIDIA 352 drivers.

Highlight the Ubuntu menu entry and  press the E key.
Add nouveau.modeset=0 to the end of the linux line.
Press the F10 key to boot into the Ubuntu system.

When the login screen appears press Ctrl+Alt+F1.
Enter your user name and password and then execute :

sudo apt-get update
sudo apt-get install nvidia-352 nvidia-prime
sudo reboot

In case everything works, you are done.
If not, perform the alternative solution.

Step 1 : Remove the installed NVIDIA 352 drivers.

Highlight the Ubuntu menu entry and  press the E key.
Add nouveau.modeset=0 to the end of the linux line.
Press the F10 key to boot into the Ubuntu system.

When the login screen appears press Ctrl+Alt+F1.
Enter your user name and password and then execute :

sudo apt-get purge nvidia*
sudo reboot

Step 2 : Install the latest NVIDIA 361 drivers.

Highlight the Ubuntu menu entry and  press the E key.
Add nouveau.modeset=0 to the end of the linux line.
Press the F10 key to boot into the Ubuntu system.

When the login screen appears press Ctrl+Alt+F1.
Enter your user name and password and then execute :

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt-get update
sudo apt-get install nvidia-361 nvidia-prime
sudo reboot


Problem flashing Ubuntu Touch Firmware on Aquaris M10 (frieza)

You can use ubuntu-device-flash with the device in fastboot mode if you pass the --bootstrap flag to ubuntu-device-flash. You will need to use that method if it won't work in recovery.


Nvm guys
I was missing a library called libtinfo
details here : https://stackoverflow.com/questions/21137879/link-error-cannot-find-ltinfo-on-ubuntu-12-04-on-a-32-bit-arm-processor
In case someone ran into the same problem


Just to note - I managed to go over this problem like this:

Once I get the "Your installation CD-ROM couldn't be mounted..." message and I'm back at the main Ubuntu Server install screen, I simply plugged the USB thumbdrive out, then plugged it in again, and then after pressing the "detect CD" option, I got "The CD-ROM autodetection was successful... The installation will now continue." ... and so the installation continued.


A complete free guide for game development in Python or C#

I agree that you'll probably get better feedback on StackOverflow but as a StackOverflower, myself, I can suggest one thing: pygame.

It's a framework that on the surface looks a bit silly but it actually hooks straight into SDL and has multiple graphics fallbacks. It does a lot of the heavy lifting for you and while that might not be what you want in the long run, I couldn't think of anything better for getting started.

They also have few well explained tutorials, including one about how to make a "punch the chimp" annoying-advert style game.


Is safe to install JDownloader on Ubuntu?

JDownloader is an opensource software, means you can inspect its source code to see whatever its infected or not.

However when you are installing it from a third party PPA, that means you have to trust the owner of that repository, because what you will download and install is already compile and packaged binary files which there is no way we can tell what it's going to do on your PC.

If the main program is some kind of malware so there is nothing you can do about it, if you install it you'll get infected.

Adware is some kind of software which show you advertise or changes and install some other advertising software on your system, Adware-free means it's not that kind of program.


Open Disk from Dash, and follow the images below:


Lenovo Legion Y720 laptop Keyboard backlight

There is a simple way for solving that, but it works only if you're dual booting.

First, boot into Windows, set the backlight as you want, then restart the computer the backlight will still be on. I've searched a lot and this seems the only way of doing it I've found that works for me.


Make pdf reading a liitle more comfortable (using okular)

The problem is probably that this pdf is only a "pdf image file".  With your cursor can you highlight words, i.  e. the actual characters. Or does just draw a box.

Image pdf can have poor image contrast.  Whereas if you use OCR  (optical character recognition) then each character is distinct from the background,  and Okular can set each independently; there by controlling your contrast ratio of light vs. dark.


How to run Streets of Rage 5 remake on Ubuntu (Natively)?

Native (linux) instructions for Ubuntu 16.04

Download the .deb file from here. Then, open a terminal, cd into the file, and run:

sudo dpkg -i sorr_5.1-1ug_amd64.deb

This installs the game on the computer. It automatically installs a launcher. Thus, you can open it from the Menu.

File source: here.

Wine instructions for Ubuntu 16.04

The following instructions allow you to play Streets of Rage Remake v5.1 using Wine (I have version 1.9.24, but it might work in others too).

In case you do not have it already, install wine. You can get the current version (1.6) by running sudo apt-get install wine. For the latest build, follow these instructions:

sudo dpkg --add-architecture i386
sudo add-apt-repository ppa:wine/wine-builds
sudo apt-get update
sudo apt-get install --install-recommends winehq-devel

Download the Windows version of the game from here. (there are some extra soundtracks in the last post)
Extract the .rar file in your local folder, wherever you want. This will create a SORRv5.1 folder.
Run the SorR.exe file with wine. Double-clicking it might be enough. If not, right-click on the file, and select "Open with Wine Windows Program Loader".

Meny entry: additionally to the above, you can create a Menu entry for the game, so that you can run easily from the Menu. To do so, open a terminal and run the following:

    cd ~/.local/share/applications/
    sudo nano SorR.desktop

The first command take you to the folder where .desktop files (and menu entries) are stored. The second creates a file. Then, copy the text below into that file (with right-click or Ctrl+Shift+v):

    [Desktop Entry]
    Name=Streets of Rage Remake
    Exec= wine /path/to/SORRv5.1/SorR.exe
    Icon=/path/to/SORRv5.1/manual/img/sorr.png
    Terminal=false
    Type=Application
    Categories=Games;

Replace /path/to/ with the corresponding path, and select the image you would like as icon, in case the one I chose is not of your like. once you have copied that, press Ctrl+O to save. To exit, press Ctrl+X.

Now, your menu entry is in the Games folder.

In-game instructions. The games comes configured for joystick. If you do not have one, then change the Controls commands, where you can select keyboard instead of joystick.

That's it. Sound works fine. Enjoy!


Deleting the index file of baloo (with baloo disabled) and after re-enabling baloo solved the issue. I suspected of baloo because it still find some old files (already deleted some months ago).
What was really weird is that baloo was capable of find some files that krunner dont find. Really really weird.


ubuntu 12.10 can't find java, but it's exists!

is java installed in general?
to find out just run

java -version

it should print out something like

java version "1.7.0_07"
OpenJDK Runtime Environment (IcedTea7 2.3.2) (7u7-2.3.2a-1ubuntu1)
OpenJDK 64-Bit Server VM (build 23.2-b09, mixed mode)

if this is the lib file is just not in place anymore, you should probably check where the file is located at and create a link to it

you can use the find command to do this

find /lib{/,32/} -name "libc.so.6"

if you found the file just create a symbolic link to it and you should be good to go

sudo ln -s /path/to/real/libc.so.6 /lib/libc.so.6

edit:

to fix the missing java run

whereis java

which should print out something like /usr/bin/java

now start ZDE using the parameter LAX_VM, so it should look like this

./ZDE LAX_VM=/usr/bin/java


How to know service name and disable it after scanning using nmap?

You can run sudo netstat -tlp will show you all open sockets, and what program is using these. We can combine this with grep to show which web server we have running:

sudo netstat -tlp | grep https
tcp6       0      0 [::]:https              [::]:*                  LISTEN      5541/apache2

We pass three parameters to netstat:

-t asks for TCP sockets only, ignoring UDP.
-l asks for listening sockets only, ignoring outgoing connections from e.g. your browser
-p asks for program having the socket open.

In this case, apache2 is running, listening to https (on IPv6 on my box, as it is has native IPv6. If it had IPv4 in addition it would be listening to 0.0.0.0:https in addition).

In this case a sudo systemctl disable apache2 would disable Apache, and close the port. Note that this depends on what's actually listening. It may not even be a service.

That said, 902 and 443 reminds me of VMWare Workstation. Do you by any chance have that installed?

IPP is probably cups, and if you don't have any printers you can safely disable it. If you have printers, you need cups, but you can limit it to listen to only loopback interface or firewall it using ufw :)


What is the preferred way of stopping MySQL server?

If you are using a modern version of MySQL, then the “best” method is the second on your list:
sudo service mysql stop

This does the same as the first, but in a manner consistent with other services on the system, making it easier to remember and work with long term.
Abstain from using the last one. Disabling and stopping are not always synonymous


You can use another linux machine to mount the microsd card and reset the permissions of /etc to 755 - sudo chmod 755 /etc. That should be sufficient.
I don't think it can be done on the broken system itself.


Remove gradients from standard applications

After hours of try-and-error I finally got it.

1.: The selector .primary-toolbar, headerbar, .maximized headerbar.titlebar:not(:backdrop) (I don't know which one of them exactly) in gtk-widgets.css

2.: The selector is placessidebar.sidebar row:selected in gtk-widgets.css

I did not find a documentation anyway...


Can no longer connect to my phone's wifi hotspot Ubuntu v 16.04

This is what worked on my Dell Inspiron Laptop.  I switched off wifi using the f2 key and then switched it on again.  That's all.

Nick


Yes it does, but it's only a 32bit build.  It does not take advantage of 64bit architecture.  It's like downloading i686 build and running on x86_64 hardware.


Switch tasks on active process to new process

Nginx depends on worker processes being able to shutdown gracefully. Apparently it can start new requests with the newly applied configuration. But it does not continue already started requests.

To quote from http://nginx.org/en/docs/beginners_guide.html:

  Once the master process receives the signal to reload configuration, it checks the syntax validity of the new configuration file and tries to apply the configuration provided in it. If this is a success, the master process starts new worker processes and sends messages to old worker processes, requesting them to shut down. Otherwise, the master process rolls back the changes and continues to work with the old configuration. Old worker processes, receiving a command to shut down, stop accepting new connections and continue to service current requests until all such requests are serviced. After that, the old worker processes exit.

Though there apparently is a way to transfer sockets to another process in Linux - see https://stackoverflow.com/questions/1997622/can-i-open-a-socket-and-pass-it-to-another-process-in-linux - it is still unlikely nginx would just 'pick up on that' and just start applying its given (new) configuration.

If the underlieing goal of this question is to apply changes to a running service without losing client connections in the future, you will probably have to ask another question.

That question may be about implementing some pause logic. Like saving state when asked to shutdown gracefully and restoring state (e.g. state associated with a certain session or request).


How to Edit Apache2.conf | Permission Denied - Amazon AWS (EC2)

Based on the communication in comments, it is visible you use account which do not have proper permissions to write in /etc

The better and more secure way to accomplish your task is:

Upload the file (via ordinary user) in /var/tmp
Login to the terminal
Become root: sudo su -
Make a backup of the original file:

cp /etc/apache2/apache2.conf /etc/apache2/apache2.conf_original

Copy the new file:

cp /var/tmp/apache2.conf /etc/apache2/apache2.conf

Restart apache


google-chrome-stable is available on a 3rd Party Repository: Google  Chrome (for Stable).

Follow the instruction for installation:

Add Key:

wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add -

Set repository:

echo 'deb [arch=amd64] http://dl.google.com/linux/chrome/deb/ stable main' | sudo tee /etc/apt/sources.list.d/google-chrome.list

Install package:

sudo apt-get update
sudo apt-get install google-chrome-stable


I had a similar problem and found this thread to be of great help:
http://ubuntuforums.org/showthread.php?t=1861133

Using the NVIDIA X server Settings, go to X server Display Configuration.
There the connected displays will appear under the dropdown menu for Display, Model. Change the configuration of both displays to twin view and save. That should work.
If it throws an error... follow these instructions:

getting dual monitors to work on 11.10

I hope it helps!


Try this..

mysql -h 127.0.0.1 -P 3306 -u root -p *database*


Desktop environment that enables split screen shortcut?

Today I switched to Gnome desktop. You can use the exact same shortcut to split the screen.


Ubuntu 20.04 "Ubuntu Software" tells me there's an update to Core 18

The Software app in 20.04 has a bug that notifies the user of an update to a package that isn't installed. If you ignore this notification it disappears the next time you open the Software app and it never comes back.
I have core and core18 snap packages installed in 20.04. core18 was automatically installed as a dependency of another snap package. The software app in 20.04 has a bug in it that it shows an available update for a snap package that isn't installed, for example core16. When you click the Update button a notification pops up that says Unable to update core: snap has no updates available as shown in the screenshot, even though the results of snap list show that the core16 snapd-runtime environment is not installed. Not only that but core16 does not have a stable channel, only beta and edge candidates, so I ignored the green number next to Updates on the toolbar. The next time I opened the Software app the Update notification for core16 was gone, and it has never reappeared since then.


Installed some new software and added a user, now my first user crashes X and can't login

Delete the file ~/.Xauthority from user's home folder.

Also try to delete /etc/X11/xorg.conf

Re-install xorg

Reboot


How to install and/or run Universal Media Server on Ubuntu 14.04?

You are probably running ums with root privileges, which is what the documentation states against. You need to create a new account on your install or use your own profile. This is also the reason why debug.log is not generated.

Steps to follow :
login as root or > sudo -i , once you are in your own account command prompt.
enter password

> update-rc.d -f UMS remove
> exit
> sudo chown YOURUSER:YOURGROUP -R /opt/ums
> chmod u=rwx,grx,o= -R /opt/ums

Now, if you look in the opt/ums directory you will find a folder named linux. This actually contains the versions of ffmpeg and tsMuxeR we need. so change these paths in UMS.conf

> cd /opt/ums
> nano UMS.conf

Search for section "# Non-GUI Options"
then start with changing paths as follows :

mencoder_path = /usr/bin/mencoder
ffmpeg_path =/opt/ums/linux/ffmpeg
mplayer_path = /usr/bin/mplayer
......

if you need to check the paths use : whereis mencoder

Once done, if there are any packages missing like mencoder, manually install them from their respective websites.
for remaning just use this with root login:

apt-get install mediainfo flac

This should install all required codecs. Update paths accordingly in UMS.conf file. Then run UMS.sh with your own profile as
./UMS.sh
If there are any errors post them here.


16.04 - system hangs at boot time at "Started Update UTMP about System Runlevel Changes"

I landed here by googling 'lubuntu 16.04 started update utmp about system runlevel changes'. I saw this same message and I thought the system hanged. But actually I could ctrl-alt-f1 and switch to console. Eventually this thread solved my problem:  http://ubuntuforums.org/showthread.php?t=2321317&p=13478810#post13478810 In short, I did sudo apt-get install xserver-xorg-video-intel and rebooted, then everything went ok.

My background situation is different from yours, though. My setup is quite simple -- it doesn't involve loopmount. However, it was not a straight install either. I installed lubuntu in a lenovo x220i notebook, booted into a different partition, tar czf the lubuntu 16.04 partition, transferred the .tgz to an old computer (which I can't find make and model for now), tar xzf the image into an empty partition, and set up the extlinux boot loader.


unable to download updates failed to refresh cache the repository download.docker.com does not exist

Let's review...
The error message says:
...The repository 'https://download.docker.com/linux/eoan Release does not have a Release file.'

You have a source file, /etc/apt/apt.sources.d/dockerlist that contains the following entry:
deb [arch=amd64] https://download.docker.com/linux/ubuntu eoan stable

Note the resemblance: Now you know which source is triggering that message. And you know which file that source is in.

Next, let's try that source URL in a web browser:  https://download.docker.com/linux/ubuntu/
It brings up a web page. If you look on that page under the dists/ link, you will see that Eoan (19.10) is not listed. There are NO packages for your release (Eoan/19.10) at that source.
As you have discovered, adding a source that has no packages for your release of Ubuntu will trigger warning messages.
How to eliminate the warning messages:

Delete the source.  Use sudo rm on that source file.
Then run sudo apt update to refresh your package database. Always perform an update when you add, delete, or change any package source.


failed installing libamd2.2.0, libumfpack5.4.0 and libatlas-sse2-dev

The first two library packages are now libamd2.3.1 and libunfpack5.6.2. As for the last package, libatlas-sse2-dev is a virtual package, which means it no longer exists as a standalone package, but might be provided by some other package (that I haven't found yet).


Keyboard and mouse not working in X.Org - Ubuntu 18.04

Ubuntu 18.04 is Long Term Support (LTS) version. Thus stability is preferred and Wayland is probably considered relatively new technology (despite it is almost 10 years old). Older 17.10 already used Wayland in some cases with no problem, so I would recommend it over X.org, as it is much more modern and is expected to replace X.org entirely in near future.


try going into Terminal (CTRL+ALT+T) and type alsamixer and hitting return. Is the mic volume high enough? I found that my microphone would default to zero volume for some reason in this, despite it being full in the settings.

The default view in alsamixer is master levels, so it might be best to press F4 to show capture levels. Then (on mine anyway) whenever I have restarted my computer internal mic level is 0 - try using the left/right arrow keys to highlight internal mic, up and down to choose level (press h to get a list of keys to adjust settings)


There is a very simple solution, posted here: https://ubuntuforums.org/showthread.php?t=2167879

Simple use the command:

sudo cp xorg.conf /etc/X11/xorg.conf

This creates a brand new xorg.conf file.

As a side note, there are no 3D drivers for SiS video cards in Ubuntu. This fix only applies to the 2D drivers. In short, you cannot use Unity and must use a lighter DE.

Even more, it is not recommended to even use SiS video cards with Ubuntu flavors past 12.04. From here: https://wiki.ubuntu.com/Lubuntu/AdvancedMethods#SIS_graphics

  SIS graphics
  SIS graphics should be run with flavours or re-spins of Ubuntu 12.04 LTS, for example Bento, Bodhi, LXLE.

(I recommend just getting either a new PC, or a new video card. There won't ever be 3D drivers for SiS cards in Linux, nor will there be continued support)


Note that the wiki page says your output may be different. You can follow the discussion about this example that led to that warning being added to the Wiki page at LinuxQuestions.

In general, these differences are based on how things like libc (and maybe gdb) are compiled on different systems. Note that the example is run on Fedora, not Ubuntu; so the base system may have some key differences in how it's setup.

I think this is the main reason for the difference. In fact, I ran the example on Fedora and received output that was more or less identical to the output in the example.

The larger point is that the output you are receiving is the normal output for Ubuntu. I got the same output. You can issue the bt command from that point and the next set of output will be very similar to the output in the example.

So why is gdb looking for assembly files when you are working in C? Well, keep in mind that it's libc that is looking for the assembly file. GDB is just reporting what happened.

And libc is looking for the assembly file essentially because it is supposed to: parts of the library are implemented in assembly.

I'm not a guru in the inner workings of the the C standard library or assembly, so I want to be careful not to say something that is incorrect.

But note 2 things about this example:

It's about length, which by definition will get into system dependent definitions.

If you look at the message, you will see that indeed the lib is looking into it's own internal sysdeps directory, where system dependent directories are stored . This directory is part of the compiled library and is not part of the visible filesystem on the computer.

According to the GNU C Library documentation this structure is created based on the result of the configure utility, which determines how the library is compiled.

If you look at the source code for libc you will see that strlen calls hidden built-in functions based on system architecture, which in turn calls another hidden built-in system dependent assembly strlen.S (I count 18 files with that name, all for different archs), which in turn calls (or may call?) an additional hidden built-in .S function for different processors. The sse and pminub relate to processor details.
And why isn't it finding the file? I imagine it doesn't find it because it is not there. The compiled binary doesn't include it (I presume) because it is not needed on this system and configure did not say it should be created during the build.

The point here is that the example is passing a NULL to a function that expects a string, which is a big error. Unlike in higher-level languages, the compiler does not catch this. The result is undefined behavior, so anything can happen.

My guess is that the library is trying to find the the version of the function that it thinks makes the most sense; but since the NULL is meaningless here, it guesses wrong and looks for a version that is not there.

Either way it will fail with a core dump. I would also guess that the library compiled for Fedora does not exhibit exactly the same behavior because of various system differences and because any behavior is legal at this point.


Extracting meta data from raw images (DSLR camera)

From the description of the package exifprobe:

Exifprobe reads image files produced
by digital cameras (including several
so-called "raw" file formats) and
reports the structure of the files and
the auxiliary data and metadata
contained within them. In addition to
TIFF, JPEG, and EXIF, the program
understands several formats which may
contain "raw" camera data, including
MRW, CIFF/CRW, JP2/JPEG2000, RAF, and
X3F, as well as most most TIFF-derived
"raw" formats, including DNG, ORF,
CR2, NEF, K25/KDC/DCR, and PEF.
http://www.virtual-cafe.com/~dhh/tools.d/exifprobe.d/exifprobe.html

Does that work?


Try installing the open source java plugin sudo apt-get install icedtea6-plugin

It works for me.


How can I add and keep synced my gmail contacts in evolution?

You could just use the gmail web client.

Or you can go into evolution and add your google account as an address book:


I'm having ubuntu 14.04.4(server) with open ssl version 1.0.1f version. AM i vulnerable to heartbleed?

openssl version -a

If your build is older than April 7 2014 it may be vulnerable (from https://blog.pay4bugs.com/2014/04/08/howto-update-ubuntu-to-fix-heartbleed-ssl-bug/)

Your build is from feb 29 2016 - so not vulnerable

If you want to know the overall quality of your certificate and it is available from internet - check:

https://www.ssllabs.com/ssltest/index.html


How to install Xen-Tools on Ubuntu Server LTS 16.04 with Xenserver 7?

You first need to find out the physical path to the DVD drive by running:

sudo lsblk -f

The output can look like this:

NAME                 FSTYPE      LABEL           UUID                                   MOUNTPOINT
sr0                  iso9660     XenServer Tools 2017-02-14-21-45-52-00
xvda
├─xvda1              ext2                        b874af3a-24ec-454f-a802-0fee2945e388   /boot
├─xvda2
└─xvda5              LVM2_member                 LOmK2X-RYRD-GR8s-Guzv-kXFN-e3Y8-gSVdgM
  ├─nginx--vg-root   ext4                        2dd0c496-ea05-4027-bf90-84ceb94d2f3a   /
  └─nginx--vg-swap_1 swap                        77064139-1d50-4344-ade7-dacec1e62c9b   [SWAP]

As you can see, I already "inserted" the Xen Tools disk and the drive has /dev/sr0 physical path. Then, you need to create a directory where the drive will be mounted and then mount it:

$ sudo mkdir /mnt/dvd
$ sudo mount /dev/sr0 /mnt/dvd
mount: /dev/sr0 is write-protected, mounting read-only

Then, run the installer

cd /mnt/dvd/Linux
sudo ./install.sh


Ask lsof (man lsof).

sudo lsof -i :6700

Note: Really read man lsof! I'm not sitting at a linux box right now.


The same happened to me, and the only way I could make it work was installing the 1.3.2 version from sourceforge.

If you want to do it, it's easy with a couple of hints.

Installing

After compiling it myself, I realised there's another tar already compiled here. Click on the tuxguitar-1.3.2-linux-x86_64.tar.gz.

Unpack somewhere, and you will see a tuxguitar.sh inside. Launching with ./tuxguitar.sh everything works. By default it uses the "Gervill" thing that other answers say to use.

Compiling tuxguitar from source

warning: I only recommend this if no other option worked. I guess there are other easier ways.

You will need mvn (sudo apt-get install maven), and a java version installed (it's likely you already have java 7 or 8, type java -version to find out).

At the moment, as the ubuntu package only lists up to 1.3.1, uninstall your current tuxguitar (and all the plugins).

Once you have downloaded the tar, this is what I did. I'm sure there are better ways, but this worked:

tar zxvf tuxguitar-1.3.2-src.tar.gz
cd tuxguitar-1.3.2-src/build-scripts/tuxguitar-linux-x86_64-deb/
mvn install -DskipTests
cd target/
sudo dpkg --install tuxguitar-1.3.2-linux-x86_64.deb
/opt/tuxguitar/tuxguitar.sh


Permanently disable color in default terminal

In your .bashrc file, you'll find lines

# uncomment for a colored prompt, if the terminal has the capability; turned
# off by default to not distract the user: the focus in a terminal window
# should be on the output of commands, not on the prompt
force_color_prompt=yes

Put a # comment sign in front of force_color_prompt=yes line and restart terminal. After the change, the line should be

#force_color_prompt=yes

Edit: This will turn of the color from terminal. But if some programs has color support built-in in them and if you want to turn them off too, follow @Zanna's answer. Basically you need to comment out the lines like alias ls='ls --color=auto' etc.


Openstack autopilot test drive alternative to vsphere?

I'm not sure I understand. Do you have ESX servers that you can connect to vsphere? Or, when you say vsphere is not supported in ubuntu, do you mean the client part?

If it's just the client, then indeed you are out of luck. I suggest to download an official Windows VM image from http://dev.modern.ie and use IE inside it to access vsphere and set things up.

Otherwise, if you have machines with enough RAM, you could create VMs in them with virt-manager, register them with MAAS as if they were bare metal machines, and use that to install a) the autopilot; and b) the cloud, using autopilot.


Monitor detected in Windows 10 but not Lubuntu

The problem has disappeared as mysteriously as it appeared. So, at least for the time being, it's solved.


Ubuntu Kernel Panic on installation (quanta s215-x12ks)

debian-8.10.0-amd64-netinst.iso - OK
Need small configure BIOS settings...


if your software is going to be used by OTHERS and you do not use a debian installer (ie. tar.gz, with either source or compiled software) it is called a "3rd party application" and the program should be installed in /opt/{softwarename-versionnumber}/ and offer that as the default installation directory.

If this software is intended to be installed with a debian installer (ie. a DEB) files should  be placed in the default location as described in How to understand the Ubuntu file system layout? Ubuntu/Linux installers use this lay-out and tend to enforce this method when you want to package and share your software through the default method of installing (Ubuntu software center)

If the software is just for your own purpose I myself would use /opt/ or a directory with "local" (those are dirs for software/binaries you create for yourself and for your own machine, not intended to be shared,) in it but it is up to you to decide.
software installed in /opt/ will be installed by the admin and by default set to "root" using "sudo". The easiest way to change the permissions is to change owner and group (chown -r $USER:$USER) if you have a single user machine. If it is a multi user system the same can be done u but the group (the 2nd $USER in the previous command) needs to be one that includes all those users.

There should be no need to have to use chmod; the software in /opt/ should already come with sane defaults and all the permissions set correctly!  Mind that some software installed in /opt/ can ask for a user to use and set the software already for that user.

  From what I’ve read, there is no ‘standard’ for installation directories

The Filesystem Hierarchy Standard is a pretty good standard and is a widely accepted method for Linux operating systems. And is maintained pretty well (the next big change will be a separation such that we can have a read-only filesystem for / and partitions that hold the writable part of the installation.


No audio over USBC to HDMI on Ubuntu 18.04

I had the same problem between my Ubuntu 18.04 laptop (Dell XPS 13) and Sharp Aquos TV. The HDMI output was not showing in the list of possible Sound outputs.
I solved it by restarting the laptop. The HDMI output option appeared and I was able to select it.


Failed update to 18.04, no GNOME or any desktop

The following list of actions solved the problem:

sudo apt-get update
sudo apt-get install ubuntu-desktop
sudo apt-get install gnome-core lightdm
sudo dpkg-reconfigure lightdm # select LightDM

then OP successfully logged in to the session.


Not an awk or sed solution, but I hope this helps anyway. Are the same numbers always supposed to be replaced by the same letters? If not:

perl -pe 's/[0-9]/chr 97+rand 26/eg' input.txt

If they are, then this is one solution:

perl -MList::Util=shuffle -M5';$x=join"",shuffle a..z' -pe 'eval"tr/0-9/$x/"' input.txt

Update: For shorter versions of the second one, see this thread.


How can I make a bootable usb from ubuntu? I want windows 10 Back

I use Woeusb to create bootable usb with win10 and it works,I was able to run it and install win10 but you must search to find Woeusb that will work


So I'm on ubuntu 20.10 with kernel 5.8.0-44-generic. My Intel Wi-Fi 6 AX200 was working fine until one day when something changed and it wasn't.
I got something like this:
dmesg | grep iwl
[    2.536811] iwlwifi 0000:03:00.0: enabling device (0000 -> 0002)
[    2.570596] iwlwifi: probe of 0000:03:00.0 failed with error -110

and:
lshw -C network
*-network UNCLAIMED
       description: Network controller
       product: Wi-Fi 6 AX200
       vendor: Intel Corporation
       physical id: 0
       bus info: pci@0000:52:00.0
       version: 1a
       width: 64 bits
       clock: 33MHz
       capabilities: cap_list
       configuration: latency=0
       resources: memory:ebb00000-ebb03fff

But today when I restarted, it managed to successfully find a version of the firmware that works with my kernel for the AX200, it's: 55.d9698065.0 cc-a0-55.ucode.
Which you can find here: https://www.intel.com/content/www/us/en/support/articles/000005511/wireless.html, or specifically in the firmware git tree: https://git.kernel.org/pub/scm/linux/kernel/git/firmware/linux-firmware.git/tree/ where you can see a bunch of them, version 55 included:
-rw-r--r--  iwlwifi-cc-a0-46.ucode  1044452 logstatsplain
-rw-r--r--  iwlwifi-cc-a0-48.ucode  1096704 logstatsplain
-rw-r--r--  iwlwifi-cc-a0-50.ucode  1101228 logstatsplain
-rw-r--r--  iwlwifi-cc-a0-53.ucode  1205332 logstatsplain
-rw-r--r--  iwlwifi-cc-a0-55.ucode  1219356 logstatsplain
-rw-r--r--  iwlwifi-cc-a0-59.ucode  1261280 logstatsplain

Hope that helps you and anyone else with this issue. You can manually download that version, put it in your /lib/firmware/ folder and modprobe it (?).
dmesg | grep iwl
[    2.621470] iwlwifi 0000:3e:00.0: enabling device (0000 -> 0002)
[    2.635643] iwlwifi 0000:3e:00.0: Direct firmware load for iwlwifi-cc-a0-56.ucode failed with error -2
[    2.637078] iwlwifi 0000:3e:00.0: api flags index 2 larger than supported by driver
[    2.637092] iwlwifi 0000:3e:00.0: TLV_FW_FSEQ_VERSION: FSEQ Version: 89.3.35.22
[    2.637096] iwlwifi 0000:3e:00.0: Found debug destination: EXTERNAL_DRAM
[    2.637098] iwlwifi 0000:3e:00.0: Found debug configuration: 0
[    2.637453] iwlwifi 0000:3e:00.0: loaded firmware version 55.d9698065.0 cc-a0-55.ucode op_mode iwlmvm
[    2.637481] iwlwifi 0000:3e:00.0: Direct firmware load for iwl-debug-yoyo.bin failed with error -2
[    2.812223] iwlwifi 0000:3e:00.0: Detected Intel(R) Wi-Fi 6 AX200 160MHz, REV=0x340


Boot doesn't display Windows XP and Ubuntu to select the OS

Run sudo update-grub. Sometimes it happens that during installation, the bootloader doesn't detect windows. If it still doesn't show windows. Then just to check that everything is alright, check the file grub.cfg in the folder in the root directory ./boot/grub/ . If it displays the words that go something like "Windows * (loader)" then everything is alright with the grub.cfg file. If this happens, comment.


Missing dependencies message after login

It looks like that in Ubuntu 19.10 the gir1.2-networkmanager-1.0 has been replaced by the package gir1.2-nm-1.0 (see this page)

Try to search this package by doing:

sudo apt-cache search -n gir1.2

if you find this package, you can install it:

sudo apt-get install gir1.2-nm-1.0

Hope it will works for you.


How to create LV(Logical Volume) after ubuntu is installed?

LVM can be set up after the system is installed. But putting the root partition on the LVM after the fact is quite difficult and probably would be better done with a reinstallation. Furthermore, it is not possible to just create a LVM on a already mounted partition.

But it seems that the main goal is to provide some space on a LVM for Xen domains. This can be done by shrinking /dev/sda1 and creating a new partition /dev/sda2 for a LVM physical volume.

Warning: The procedure described below will change your partitions and filesystems. If there is any data on this system you cannot do without, a backup is strongly recommended.

While it is possible to resize a mounted filesystem and partition, it is not recommended and should only be done if you really know what you are doing. I'd recommend using the GParted Live System. It provides graphical tool, to easily resize partitions and create new ones.

Create a GParted Live CD or USB drive and boot from it. Once it is running, there is a desktop with some icons. Open the one saying GParted.

In the GParted program select your hard drive (it should say "/dev/sda (60 GiB)"). Right-click on the partition ("/dev/sda1") and select "Resize/Move". You now can set the size in "New Size (MiB)". Depending on what you want to do with the system itself, I'd recomend to leave at least 12 GiB for your system (you already use 4.2 GiB and you may want to be able to download ISOs for installation of your Xen guests). Ensure that it still says "0" in "Free space preceeding (MiB)", as you want to create the new partition after your root partition. Save the changes.

Now right-click on "unallocated" and select "New". Change "File system" to "lvm2 pv". The rest should already be set to fill the entire free space. Add the partition.

Finalize these changes by clicking on "Apply all Operations" (either the check mark in the toolbar or in the "Edit" menu)

Restart your machine to your own system.

Now you can create a volume group on /dev/sda2

# vgcreate vm /dev/sda2

Then locical volumes can be created in this volume group with

# lvcreate -L 10G -n lv0 vm

The new logical volume will have a size of 10 GB and be named "lv0". It's device will be named /dev/mapper/vm-lv0.

The logical volume may then be formatted with a filesystem, for example ext4

# mkfs.ext4 /dev/mapper/vm-lv0

Note that creating the logical volumen may already be done by the tools used to set up the Xen domain and formatting will usually be done by the system setup inside the virtual machine.


To remove all mkv files recursively except FINAL.mkv you can do :

find . -type f -not -name '*FINAL.mkv' -name '*.mkv' -delete

Use -type f to search for only files
-name '*.mkv' will get us all .mkv files
-not -name '*FINAL.mkv' will leave out all the *FINAL.mkv files
-delete will remove the files found.

Also do a dry run by the following at first to check that everything is all right :

find . -type f -not -name 'FINAL.mkv' -name '*.mkv'


How to disable the notebook Touch Pad when a wireless USB mouse is connected

Definitely not the only way, but one way to do it would be to install gpointing-device-settings and check the "Disable while any other devices are connected" checkbox in the "General" tab for your touchpad.


No need to add routes on the router. They're already directly connected there as a local interface! You can see that by running route -n. E.g.:

route -n
Kernel IP routing table
Destination     Gateway         Genmask         Flags Metric Ref    Use Iface
0.0.0.0         192.168.25.1    0.0.0.0         UG    0      0        0 wlan0   # def.gw
169.254.0.0     0.0.0.0         255.255.0.0     U     1000   0        0 wlan0   # zeroconf
192.168.0.0     192.168.25.254  255.255.255.0   UG    0      0        0 wlan0   # route
192.168.11.0    0.0.0.0         255.255.255.0   U     0      0        0 testvpn # interf.
192.168.25.0    0.0.0.0         255.255.255.0   U     2      0        0 wlan0   # interf.
192.168.122.0   0.0.0.0         255.255.255.0   U     0      0        0 virbr0  # interf.

I've marked an actual route added manually here with # route. You'll notice that these lines are also listed with the G flag! The ones without that flag are just local, directly available.

The only thing you'll need to enable is IPv4 forwarding.

sudo sysctl -w net.ipv4.ip_forward=1

and enable it permanently by putting this line in a /etc/sysctl.d/10-routing.conf (you can make up a name) file:

net.ipv4.ip_forward=1

From here you'll have to tell the hosts in the networks about these routes. So, on a machine in the 10.100.0.0/16 for example, you'll need to add the routes like this:

# On a client somewhere in 10.100.0.0
auto eth0
iface eth0 inet static
  address 10.100.0.123
  netmask 255.255.0.0
  # route 10.0.0.0/16 via 10.100.0.4
  up route add -net 10.0.0.0 netmask 255.255.0.0 gw 10.100.0.4
  # route 10.101.0.0/16 via 10.101.0.1
  up route add -net 10.101.0.0 netmask 255.255.0.0 gw 10.101.0.1

A much better way to announce these routes is to tell them by using DHCP, or to make it the default gateway by using gateway. Alternatively, use 'real' routing protocols such as OSPF, RIP, etc.

By the way, the syntax in your /etc/network/interfaces file is wrong. The up entries should be part of each individual interface listed, indented by spaces such as the address entry.


How to make the keyboard media keys to work with VLC globally?

I had a similar problem and the issue was that Gnome would capture the media keys before they reached VLC, to fix this you can go to "System->Preferences->Keyboard Shortcuts"

There you will see a header called sound (Expand it if needed), and remove the key combinations you want in VLC from there (You can disable them by clicking on the item and then pressing backspace).

Only problem with this is that any other applications that do use Gnome's built-in handling won't work anymore with the media keys, unless you add them again (Which in turn breaks VLC again)


How to change permission external hard drive in ubuntu 12.04

Also try this
Open nautilus file manager as root by typing following command in terminal

sudo -i

Now enter your password

Now open nautilus file manager by typing nautilts in the terminal

Now find your external hard disk on nautilus file manager and open properties of your external hard disk.

Now click permissions tab and change file access  to read write.


Why do I get a blank screen when starting Wubi?

By default, Wubi does not install on a different partition. It creates a virtual "hard disk" file within your primary storage drive (typically C:), from which it runs Ubuntu.

If you intentionally instructed it to create this disk on a separate partition of your drive, it could be that Windows is having issues interacting with it. Can you access that partition's letter from Windows (specifically, the Wubi directory, which is X:/ubuntu, where X is the respective drive letter)?

If you simply mistook the function of the Wubi installer, then I'm not quite certain. It could be a corrupted .iso file, or perhaps an incompatible one (I'm not sure if a 64-bit Ubuntu .iso can be installed over a 32-bit Windows system, for example). It could also be that, for whatever reason, Wubi didn't install the grub2 bootloader (the bootloader which appears after you select Ubuntu after boot) correctly.

If I were you, I'd just uninstall Ubuntu through the Control Panel or by running Wubi again (it should prompt you to uninstall), and reinstall it, making sure it is on the same partition as your Windows installation.

edit - It could also be that your hard drive is overly fragmented (though this is unlikely). If none of the above solutions work, running the Windows defrag tool after installation might help.


When this happens on a Wubi installation, it is is generally due to:

Minor partition table errors
A MBR partition table but some leftover GPT partition table data
Unsupported raid

Probably the best way to diagnose would be to boot an Ubuntu CD as a live CD (select Try Ubuntu without installing) and run the bootinfoscript.

You can also just hit CtrlAltF1 when you get that error to drop to a terminal and run:
sudo parted -l and sudo fdisk -l
The first will tell you if there are partition table errors. The second will tell you if there is some leftover GPT data (usually if you reuse a disk from a Mac). If you need to remove this GPT data you can use fixparts found here.

For example, this sudo fdisk -l output shows that a GUID partition table is detected, but does not seem to be used:

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders, total 976773168 sectors
Units = sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 512 bytes

Partition Boot Start Sector End Sector # of Sectors Id System

/dev/sda1 * 2,048 206,847 204,800 7 NTFS / exFAT / HPFS
/dev/sda2 206,848 307,202,047 306,995,200 7 NTFS / exFAT / HPFS
/dev/sda3 307,202,048 976,771,071 669,569,024 f W95 Extended (LBA)
/dev/sda5 307,204,096 614,404,095 307,200,000 7 NTFS / exFAT / HPFS
/dev/sda6 614,406,144 976,771,071 362,364,928 7 NTFS / exFAT / HPFS

GUID Partition Table detected, but does not seem to be used.

Running sudo blkid may provide information regarding any fakeraid partitions (there are probably better tools for checking the raid setup but I'm not familiar with these).


In 14.04 how do I run a bash script I wrote without opening a terminal?

Simply create a .desktop file and save it in ~/.local/share/applications. In its most basic form:
[Desktop Entry]
Name=name_of_your_script_like_you_see_it_in_Dash
Exec=sh /path/to/script.sh
Icon=/path/to/some/icon
Type=Application

Copy it into an empty file, save it as script.desktop in ~/.local/share/applications.
After log out /in, it will appear in Dash.
If the script is executable, you can replace Exec=sh /path/to/script.sh by simply: Exec=/path/to/script.sh, or if you don't have the language extension on the script: Exec=/path/to/script
Note
If the path to your script contains (folder-) names with spaces, you can simply escape it by putting the name between quotes. For example:
Exec=sh /path/with/'Folder with spaces'/to/script.sh

(spaces in the path to your icon can/should be left as they are)


How do I fix / isntall the drivers for my touchpad for Lenovo Yoga 900 i5

Hello i have had the same problem. This https://bbs.archlinux.org/viewtopic.php?id=204355 helped me to solve. it works good except after supend. So this steel  to be solved.


Why might I want to use a clipboard manager?

Persistence is probably the best selling point for me. Most CBMs allow you to store the same items across sessions (even platforms), mobile (if your profile is) and especially in the case of X-based applications, selected items* are remembered after the source application closes (something that is not natively true).

Multiple clipboards is something I don't use too much but it' very handy if you find yourself juggling several bits and bobs at once. You can do all your copying at once and then get on with whatever you're doing. Less back-and-forth.

These are both negatives if you regularly copy sensitive data as it could be a security issue.

* Just an explanation: you do know you effectively get two clipboards out the box? There's the traditional Control+C, Control+V clipboard but there's also something called "primary selection". Select some text and then middle click where you want it pasted. I find this very useful for quick, precise, multiple pasting.


How can a non-geek set up a proper firewall?


How do I install the driver for a Microsoft Lifecam VX-3000?

Driver

The driver for this webcam is already included, and it should work out of the box. You can check if it does with cheese.

The kernel module for this webcam is called gspca_sonixj. You can check if it's loaded with:

lsmod | grep sonixj

Skype

Testing if it works

If the webcam does work in Cheese but not in Skype, that's because this webcam can only output JPEG compressed frames which Skype cannot handle. To fix this, the proposed solution of the other answers is already almost correct.

Start Skype from a Terminal window by running:

LD_PRELOAD=/usr/lib/libv4l/v4l2convert.so skype

or if you're on a 64bit system (if output of uname -m is x86_64):

LD_PRELOAD=/usr/lib32/libv4l/v4l2convert.so skype

In Ubuntu 11.10 the path changed, so for 32bit use

LD_PRELOAD=/usr/lib/i386-linux-gnu/libv4l/v4l2convert.so skype

and for 64bit use

LD_PRELOAD=/usr/lib32/libv4l/v4l2convert.so skype

In Ubuntu 12.04 the path for 64bit changed again, so use

LD_PRELOAD=/usr/lib/x86_64-linux-gnu/libv4l/v4l2convert.so skype

For 32bit see above.

Making it permanent

If this works, you can change the Menu entry similar to how @demua suggests doing:

copy /usr/share/applications/skype.desktop to a file in your Profile to prevent future updates from undoing your changes. This can be done in a Terminal with:

mkdir -p $HOME/.local/share/applications
cp /usr/share/applications/skype.desktop $HOME/.local/share/applications/

open the newly created $HOME/.local/share/applications/skype.desktop in an editor and change the line

 Exec=skype

to something like

 Exec=env LD_PRELOAD=/usr/lib/libv4l/v4l2convert.so skype

Of course you have to use the same path here as above when testing.

The workaround for Skype also works for other legacy applications and other webcams that only support unusual formats. Tested with:

Microsoft VX-3000
Hercules Deluxe Optical Glass


How to upgrade the Linux kernel to version 3.4.7

Here's a good start point: https://help.ubuntu.com/community/Kernel/Compile/

You may use many other sources on Linux kernel 3.2 (like http://mitchtech.net/compile-linux-kernel-on-ubuntu-12-04-lts-detailed/) as it's almost the same for Linux kernel 3.4.

Then, if you face any problem, you can search for a solution or come back here and ask about it.


Speakers not detected on Ubuntu 18.04.1 LTS

For an Ubuntu virtual machine in Virtualbox it works better with "Intel HD Audio" emulation.

No additional drivers are required.


Downloading the libnss3 package and installing it will resolve this issue. Just type the commands given below one-by-one in terminal to download and install libnss3 :-

64-bit

wget http://launchpadlibrarian.net/233346181/libnss3_3.19.2.1-0ubuntu0.14.04.2_amd64.deb

sudo dpkg -i libnss3_3.19.2.1-0ubuntu0.14.04.2_amd64.deb

32-bit

wget http://launchpadlibrarian.net/233346229/libnss3_3.19.2.1-0ubuntu0.14.04.2_i386.deb

sudo dpkg -i libnss3_3.19.2.1-0ubuntu0.14.04.2_amd64.deb

Another method to resolve this issue is downloading and installing of the beta desktop app of Upwork instead of stable one on Ubuntu.

Helpful links

Installing Upwork Team App on Ubuntu

Linux Troubleshooting for Upwork Team App


it may be a good idea to backup files from the win partition on a different drive before you start - if you are looking to shrink drives down before installing over windows partition as mike said a tip would be to use the micro$oft windows native drive shrinker as to avoid errors between *ix and win formatting.   Using the distro you want in live you should be able to identify what partition win core os is installed on (sda,sdb.. etc...) and when installing use that drive.


Unfortunately Roland is right, you are probably best doing this manually at the moment.

However, it is possible to change Wine's system-wide default registry settings by editing /usr/share/wine.inf -- this is the registry that new Wine Prefixes get created with.  I'm not sure how to add a theme in there, although you could look at the registry of a current Wine install after you change the theme for hints.


Changing my AIM alias in Empathy doesn't work


Digital audio workstation - software available and running on Ubuntu 16.04?

You can try out audio workstation packages on Ubuntu Studio

Can also add the Ubuntu Studio packages to any other version of Ubuntu


Ubuntu 18.04 fails to start network, netplan DHCP configuration

Please check: cat /usr/share/doc/netplan.io/examples/dhcp.yaml The correct wording is dhcp4:  true. Please amend your file to:

network:
  version: 2
  renderer: networkd
  ethernets:
    ens160:
      dhcp4: true

Follow with:

sudo netplan generate
sudo netplan apply

Reboot and let us hear your report.


Remap Keyboard Shortcut for Brightness Changing

Workaround
for increasing by 0.1 add the below command as custom keyboard shortcut
sh -c 'gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp && gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepUp'

for decreasing by 0.1
sh -c 'gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown && gdbus call --session --dest org.gnome.SettingsDaemon.Power --object-path /org/gnome/SettingsDaemon/Power --method org.gnome.SettingsDaemon.Power.Screen.StepDown'

Note: set the brightness by zero or 100 via GUI for the first time and then use the keyboard shortcuts to have perfect multiples of 10


The GUI is in System Settings - Workspace Behaviour - Activities - Privacy but it does not seem to work.


How to delete lines where certain pattern appears on the specific position

awk can do that:
awk '{if(!($1=="PDB;"&&$3=="EM;")){print}}' <yourfile

This tests if the first column (by default whitespaces are taken as the delimiter) of the current line is PDB; and the third column is EM; and prints the line only if not both are true.
Output
$ awk '{if(!($1=="PDB;"&&$3=="EM;")){print}}' <test
PEBP1_HUMAN Homo sapiens    P30086  PDB; 1BD9; X-ray; 2.05 A; A/B=1-187.
                    PDB; 1BEH; X-ray; 1.75 A; A/B=1-187.
                    PDB; 2L7W; NMR; -; A=1-187.
                    PDB; 2QYQ; X-ray; 1.95 A; A=1-187.

PECA1_HUMAN Homo sapiens    P16284  PDB; 2KY5; NMR; -; A=686-738.
                    PDB; 5C14; X-ray; 2.80 A; A/B=28-229.
                    PDB; 5GEM; X-ray; 3.01 A; A/B=28-232.

PELO_HUMAN  Homo sapiens    Q9BRX2  PDB; 1X52; NMR; -; A=261-371.
                    PDB; 5EO3; X-ray; 2.60 A; A/B=265-385.


BootFix and Splash Logo on Ubuntu 16.04.2 LTS

Your first problem is most likely caused by the fact that modern EFI-based computers store the boot loader information in NVRAM. Thus, when you mirror a working installation to a new computer, unless you explicitly add an NVRAM entry, the computer won't know how to boot. Several possible solutions spring to mind:

Create the right boot entry -- If you use the target computer to mirror the disk, you can explicitly create a boot entry with efibootmgr. Chances are efibootmgr -c -l \\EFI\\ubuntu\\shimx64.efi -L ubuntu will do the trick, although you might need to add -d and/or -p options, depending on how your disk is laid out. (See the man page for efibootmgr for details on its options.) This is likely the best solution if you're using the target system to do the mirroring; but if you pull the disk from the target system and use another computer to mirror the disk, this solution won't work unless you're willing to do some cleanup work on the target computing using an emergency disk. This solution also requires that the EFI System Partition (ESP) be mirrored along with everything else.
Use the fallback filename -- Instead of booting EFI/ubuntu/shimx64.efi, which in turn launches EFI/ubuntu/grubx64.efi on the ESP, you can copy those files so that the system uses the fallback filename of EFI/BOOT/bootx64.efi on the ESP. That is, you'd do something like sudo cp -a /boot/efi/EFI/ubuntu /boot/efi/EFI/BOOT, followed by sudo mv /boot/efi/EFI/BOOT/shimx64.efi /boot/efi/EFI/BOOT/bootx64.efi. (This would be from a working, booted installation; you'd have to adjust the path if you made these changes in some sort of emergency environment.) EFIs try to boot using the fallback filename if no explicit NVRAM entry (as created by efibootmgr) exists, so doing this should get your cloned systems to boot. The problem is that updates to GRUB won't be properly installed without extra steps.
Install in BIOS/CSM/legacy mode -- Instead of installing in the native EFI/UEFI mode, you could install in BIOS/CSM/legacy mode. When the target computers are reconfigured to support this boot mode, they should then boot without requiring NVRAM entries to point to the correct boot loader. This approach may require more fiddling with the firmware settings on the target computers, though, so it may not be worth the hassle.

You might also do a combination of the first two approaches -- that is, copy Shim/GRUB to the fallback filename for a first boot, but configure the computer to launch a script to add an NVRAM entry to the EFI/ubuntu/shimx64.efi boot loader the first time it boots.


VisualBoy Advance game colour problem - Ubuntu 12.04

Didn't find how to solve the problem, but tried a different emulator. To be specific VBA-M/VBAM and it working great with the ROM.


How to Blacklist-bcm43.conf file from being automatically edited?

Accessing a web page doesn't change any system files. According to http://pastebin.com/P6MfyjdU that file is automatically regenerated by a wireless adapter configuration tool.

I also found an article about conflicting drivers for your adapter. The lower section suggests

sudo apt-get remove --purge bcmwl-kernel-source
sudo rm /etc/modprobe.d/blacklist-bcm43.conf

Afterwards you will need to

sudo update-initramfs -u

and reboot.


My install (UBUNTU Precise) has No print drivers

With a working internet connection, please open a terminal and do:

sudo apt-get update
sudo apt-get install brother-lpr-drivers-common

The driver for the HL-1470N should now be available.


Is it possible to prevent the installation of a required package?

I have not tried this on logwatch itself, but generally ignoring dependencies is done like this:

sudo dpkg -i --ignore-depends=postfix the_package.deb

There is no way of doing this via apt that I know of.

EDIT: enzotib is right, apt will complain at a later stage of a missing dependency. Apt-pinning or changing the dependencies in the deb package might be a better way.


You may use memdisk from syslinux-common package to boot using ISO image directly though TFTP. Somehow slow (2MB/s is the best I could get using TFTP, around 5min to load)

memdisk loads iso image to RAM and mount it like virtual/fake CD drive then boot from it. So the machine should have enough RAM to hold CD and run its contained OS.

Copy memdisk & ISO images to TFTP root
Add menu entries to PXE configuration file, Example:

LABEL slitaz
    MENU LABEL ^Slitaz.iso
    TEXT HELP
Testing boot from iso.
    ENDTEXT
    KERNEL memdisk
    APPEND initrd=slitaz-cooking.iso

LABEL mini_ubutnu
    MENU LABEL Mini-Ubuntu
    KERNEL memdisk
    APPEND initrd=ubuntu_mini.iso

Reference: syslinux - memdisk


How can I watch the NBC Olympics 2012 (USA)?

As per this post on the Adobe website:

Step One: Install HAL

sudo apt-get install hal

Step Two: Quit your web browser

Step Three: Clean out the Adobe Flash folder:

cd ~/.adobe/Flash_Player
rm -rf NativeCache AssetCache APSPrivateData2

This process worked for me.  In my case, I'd been able to go to nbcolympics.com and click the log to begin the verification process, but never given the chance to enter my Comcast credentials.  Doing the steps above fixed everything.


What's the difference between <<, <<< and < < in bash?

Here document
<< is known as here-document structure. You let the program know what will be the ending text, and whenever that delimiter is seen, the program will read all the stuff you've given to the program as input and perform a task upon it.
Here's what I mean:
$ wc << EOF
> one two three
> four five
> EOF
 2  5 24

In this example we tell wc program to wait for EOF string, then type in five words, and then type in EOF to signal that we're done giving input. In effect, it's similar to running wc by itself, typing in words, then pressing CtrlD
In bash these are implemented via temp files, usually in the form /tmp/sh-thd.<random string>, while in dash they are implemented as anonymous pipes. This can be observed via tracing system calls with strace command. Replace bash with sh to see how /bin/sh performs this redirection.
$ strace -e open,dup2,pipe,write -f bash -c 'cat <<EOF
> test
> EOF'

Here string
<<< is known as here-string . Instead of typing in text, you give a pre-made string of text to a program. For example, with such program as bc we can do bc <<< 5*4 to just get output for that specific case, no need to run bc interactively.
Here-strings in bash are implemented via temporary files, usually  in the format /tmp/sh-thd.<random string>, which are later unlinked, thus making them occupy some memory space temporarily but not show up in the list of /tmp directory entries, and effectively exist as anonymous files, which may still be referenced via file descriptor by the shell itself, and that file descriptor being inherited by the command and later duplicated onto file descriptor 0 (stdin) via dup2() function. This can be observed via
$ ls -l /proc/self/fd/ <<< "TEST"
total 0
lr-x------ 1 user1 user1 64 Aug 20 13:43 0 -> /tmp/sh-thd.761Lj9 (deleted)
lrwx------ 1 user1 user1 64 Aug 20 13:43 1 -> /dev/pts/4
lrwx------ 1 user1 user1 64 Aug 20 13:43 2 -> /dev/pts/4
lr-x------ 1 user1 user1 64 Aug 20 13:43 3 -> /proc/10068/fd

And via tracing syscalls (output shortened for readability; notice how temp file is opened as fd 3, data written to it, then it is re-opened with O_RDONLY flag as fd 4 and later unlinked, then dup2() onto fd 0, which is inherited by cat later ):
$ strace -f -e open,read,write,dup2,unlink,execve bash -c 'cat <<< "TEST"'
execve("/bin/bash", ["bash", "-c", "cat <<< \"TEST\""], [/* 47 vars */]) = 0
...
strace: Process 10229 attached
[pid 10229] open("/tmp/sh-thd.uhpSrD", O_RDWR|O_CREAT|O_EXCL, 0600) = 3
[pid 10229] write(3, "TEST", 4)         = 4
[pid 10229] write(3, "\n", 1)           = 1
[pid 10229] open("/tmp/sh-thd.uhpSrD", O_RDONLY) = 4
[pid 10229] unlink("/tmp/sh-thd.uhpSrD") = 0
[pid 10229] dup2(4, 0)                  = 0
[pid 10229] execve("/bin/cat", ["cat"], [/* 47 vars */]) = 0
...
[pid 10229] read(0, "TEST\n", 131072)   = 5
[pid 10229] write(1, "TEST\n", 5TEST
)       = 5
[pid 10229] read(0, "", 131072)         = 0
[pid 10229] +++ exited with 0 +++
--- SIGCHLD {si_signo=SIGCHLD, si_code=CLD_EXITED, si_pid=10229, si_uid=1000, si_status=0, si_utime=0, si_stime=0} ---
+++ exited with 0 +++

Opinion: potentially because here strings make use of temporary text files, it is the possible reason why here-strings always insert a trailing newline, since text file by POSIX definition has to have lines that end in newline character.
Process Substitution
As tldp.org explains,

Process substitution feeds the output of a process (or processes) into
the stdin of another process.

So in effect this is similar to piping stdout of one command to the other , e.g. echo foobar barfoo | wc . But notice: in the bash manpage you will see that it is denoted as <(list). So basically you can redirect output of multiple (!) commands.
Note: technically when you say < < you aren't referring to one thing, but two redirection with single  < and process redirection of output from <( . . .).
Now what happens if we do just process substitution?
$ echo <(echo bar)
/dev/fd/63

As you can see, the shell creates temporary file descriptor /dev/fd/63 where the output goes (which according to Gilles's answer, is an anonymous pipe). That means  < redirects that file descriptor as input into a command.
So very simple example would be to make process substitution of output from two echo commands into wc:
$ wc < <(echo bar;echo foo)
      2       2       8

So here we make shell create a file descriptor for all the output that happens in the parenthesis and redirect that as input to wc .As expected, wc receives that stream from two echo commands, which by itself would output two lines, each having a word, and appropriately we have 2 words, 2 lines, and 6 characters plus two newlines counted.
How is process substitution implemented ? We can find out using the trace below (output shortened for brevity)
$ strace -e clone,execve,pipe,dup2 -f bash -c 'cat <(/bin/true) <(/bin/false) <(/bin/echo)'
execve("/bin/bash", ["bash", "-c", "cat <(/bin/true) <(/bin/false) <"...], 0x7ffcb96004f8 /* 50 vars */) = 0
pipe([3, 4])                            = 0
dup2(3, 63)                             = 63
clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f6c12569a10) = 8954
strace: Process 8954 attached
[pid  8953] pipe([3, 4])                = 0
[pid  8953] dup2(3, 62)                 = 62
[pid  8953] clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f6c12569a10) = 8955
strace: Process 8955 attached
[pid  8953] pipe([3, 4])                = 0
[pid  8953] dup2(3, 61)                 = 61
[pid  8953] clone(child_stack=NULL, flags=CLONE_CHILD_CLEARTID|CLONE_CHILD_SETTID|SIGCHLD, child_tidptr=0x7f6c12569a10) = 8956
[pid  8953] execve("/bin/cat", ["cat", "/dev/fd/63", "/dev/fd/62", "/dev/fd/61"], 0x55ab7566e8f0 /* 50 vars */) = 0

The above trace on Ubuntu (which also implies on Linux in general) suggests that process substitution is implemented by repeatedly forking multiple subprocesses (so process 8953 forks multiple child processes 8954,8955,8956,etc). Then all these subprocesses communicate back via their stdout , but that is duplicated (that is copied) onto the stack of next available file descriptors starting at 63 downwards. Why start at 63 ? That may be a good question for the developers. It is known for a fact that bash can use fd 255 for saving file descriptors for the "main" command/pipeline  when its streams are redirected.
Side Note: Process substitution may be referred to as a bashism (a command or structure usable in advanced shells like bash, but not specified by POSIX), but it was implemented in ksh before bash's existence as ksh man page and this answer suggest.
Shells like tcsh and mksh however do not have process substitution. So how could we go around redirecting output of multiple commands into another command without process substitution? Grouping plus piping!
$ (echo foo;echo bar) | wc
      2       2       8

Effectively this is the same as above example, However, this is different under the hood from  process substitution, since we make stdout of the whole subshell and stdin of wc linked with the pipe. On the other hand, process substitution makes a command read a temporary file descriptor.
So if we can do grouping with piping, why do we need process substitution? Because sometimes we cannot use piping. Consider the example below - comparing outputs of two commands with diff (which needs two files, and in this case we are giving it two file descriptors)
diff <(ls /bin) <(ls /usr/bin)


I had the same problem with QtCreator on the same machine model. At first, I also looked for the graphics drivers, but I noticed that Qt worked perfectly when run with sudo.

So I searched in environment variables, and I noticed that QtCreator works when QT_LINUX_ACCESSIBILITY_ALWAYS_ON is not set. I think this setting forces the screen reader to read the code, which Qt does not like.

After searching, I found a script /etc/X11/Xsession.d/90qt-a11y that export this variable on session opening. Simply commenting on this line and restarting the session solved the problem.


What is the difference between Ubuntu, Kubuntu, Xubuntu and Lubuntu restricted extras/addons?

-addons vs -extras

Looking at the packages it's easy to tell these are metapackages - they're just depending on other packages and are empty by themselves. The only reason for their existence is to ease the user in installing a set of packages by just setting dependencies.

By looking at the dependencies of these you can see that -extras is depending on -addons, thus making the former an extension on the latter.

The description of both packages (apt-cache show ubuntu-restricted-addons):

  Commonly used restricted packages for Ubuntu

  This package depends on some commonly used packages in the Ubuntu
  universe and multiverse repositories.

  You should not install this package directly, but instead install the
  ubuntu-restricted-extras package.

apt-cache show ubuntu-restricted-extras:

  Commonly used restricted packages for Ubuntu

  This package depends on some commonly used packages in the Ubuntu
  multiverse repository.

  Installing this package will pull in support for MP3 playback and
  decoding, support for various other audio formats (GStreamer plugins),
  Microsoft fonts, Flash plugin, LAME (to create compressed audio
  files), and DVD playback.

  Please note that this does not install libdvdcss2, and will not let
  you play encrypted DVDs. For more information, see
  https://help.ubuntu.com/community/RestrictedFormats/PlayingDVDs

  Please also note that packages from multiverse are restricted by
  copyright or legal issues in some countries. See
  http://www.ubuntu.com/ubuntu/licensing for more information.

Now that mystery is solved, let's see what the differences are on the Ubuntu derivative part.

ubuntu- vs kubuntu- vs lubuntu- vs xubuntu-

This just depends on what the derivatives have decided on to ship and recommend. Sometimes this includes Desktop Environment specific packages. Some examples:

The dependency on libk3b6-extracodecs in kubuntu-restricted-addons is only valid for KDE as this package is for K3b (KDE disc burning application) only.
The lubuntu set appears to contain a lot less dependencies and especially excluding the gstreamer codecs. This may indicate that LXDE's default player is not GStreamer based, and it's sane not to install all kinds of GStreamer libraries probably not being used in a Lubuntu installation.


How do I fix my black screen after booting with nvidia drivers?

This one can be done from recovery mode.
Restart your computer and press the SHIFT button while booting. This should offer you a text screen where you can pick recovery mode.
From there, drop to a prompt and simply remove the Nvidia drivers you added. It's possibly a good idea to reboot at this point rather than installing new drivers, just to be sure.
When you reboot, open the terminal and enter:
sudo ubuntu-drivers autoinstall

Press ENTER and let apt do its thing, rebooting when it has finished. When you reboot, you should have the proper drivers installed and running properly.


How do I change xsetwacom and make the settings stay on startup?

Write xsetwacom commands into ~/.xinitrc.

xsetwacom deliberately doesn't keep settings between X server restarts. The easiest (and safest) way to get stable settings is to just stick your list of xsetwacom commands into a shell script and add it to your startup applications.

Alternatively, you can bypass xsetwacom comletely and put your tablet settings in /usr/share/X11/xorg.conf.d/50-wacom.conf -- the "wacom" manpage lists the option lines. As always, be careful and remember that a poorly formed conf can render your device unusable.


How to remove GRUB Rescue prompt after deleting Ubuntu partition?

if you again install ubuntu (or any distro) alongside your windows then you can get both OSes again.Or if you dont want to use dual boot then install your windows again.You should format drive c while installing new windows in it.Your problem will be solved.


Can't mount NTFS drive - "NTFS signature is missing."

You are trying to mount whole Hard Disk drive instead of Partition on it. Try mounting /dev/sdc1 instead of /dev/sdc.


What are those 'x xx' in 'ls -l' command

Try:

LANG=C ls -l

There should be a month name, for example (Dec):

drwxrwxr-x. 15 user user    4096 Dec  4 16:22 NetBeansProjects

May be locale setting are incorrect


How do I get Wingpanel to replace the default Gnome Panel?

To completly disable Gnome Panel run gconf-editor and navigate through Desktop → Gnome → Session → Required Components and double click on panel and remove value gnome-panel (make the field blank).

How do I use the gconf editor?


Upgraded to 16.04.5 without dist-upgrade and can I go back?

dist-upgrade is irrelevant to a point release, your system gets this just through regular updates.  The ".x" will update when a certain small package called base-files is released through the regular update system.

If you look in your /var/log/apt logfiles for the day that your system changed to .5, you will find that this package got installed.

Here are comments on a point release from the official Ubuntu blog (emphasis mine)

  If you’re already running 18.04 LTS, and you have been updating
  regularly, then you will already have all of these applied and so
  essentially you’re already running 18.04.1 LTS. The point release is
  an opportunity for us to make a new ISO image, and so people
  downloading and installing from the release of the new images will
  benefit from having those updates available immediately.

For more information about what dist-upgrade is, read the accepted answer to this question.  TL;dr, dist-upgrade does not upgrade your system to a new release, it is merely a version of upgrade that is allowed to remove packages to resolve conflicts.


As you're "new to Linux", I won't suggest compiling from source. Instead, there is a PPA that you'll need to add to apt so that you can use 3.9. Here are the steps:

Open Terminal (if it's not already open)
Update apt and confirm that you have the prerequisites installed:
sudo apt update
sudo apt install software-properties-common

The PPA you'll need to add is maintained by "deadsnakes", so let's add that:
sudo add-apt-repository ppa:deadsnakes/ppa

You'll be asked if you want to continue. Press Enter to do so.
Update apt again:
sudo apt update

Install Python 3.9:
sudo apt install python3.9

Confirm that the installation was successful:
python3.9 --version

You should see:
Python 3.9.1+

That's all there is to it. When you use anything that specifically requires Python 3.9, be sure to use python3.9 as the command, not python or python3.
Warning: Do not remove the default version of Python(3.x) which was preinstalled in Ubuntu, even if you install Python 3.9. Removing the default python version may break your system.


Not able to find the pages after running Node server on Ubuntu

I guess you did not have the make tools available when you installed your mongodb library. I suggest you do

sudo apt-get install gcc make build-essential

and run

rm -rf node_modules
npm cache clean
npm install

OR just npm update

npm update

Edit 1

In the file node_modules/mongoose/node_modules/mongodb/node_modules/bson/ext/index.js, change the line

bson = require('../build/Release/bson');

to

bson = require('bson');


gnome-terminal keeps the menubar even when the profile is configured to hide it

In my case it was related to Eliminate the top "mac-ish" file/edit/view/... menu after installing gnome?

When I moved my top bar away with Alt + Right click (for example to the right side of the screen) an extra menubar showed up on the top of the screen. It was probably hidden under the top bar I moved away.

After running sudo apt-get remove appmenu-gtk3 appmenu-gtk appmenu-qt and a reboot gnome-terminal --hide-menubar worked again :-)