GNU Screen is a tool that lets you reattach to a previous session. Just install it on your remote server.

apt-get install screen

Now when you connect to the machine via SSH, just type screen and press Space. You will be back to your normal terminal. Run whatever you want (minecraft) here.

Now assume your connection dropped. Buy don't worry, because it is still running in the screen session you created before. All you have to do is to re-SSH and the attach to the already running screen session. You can get a list of running sessions by:

screen -ls

From the list, choose the session you want to connect to and type:

screen -r <session-name>

And you are back!

This is one of the many awesome things you can do with screen. I have written only the minimal usage information required to achieve what the OP wanted. Here is a good tutorial if you are interested.

To exit the screen session, just type exit.


Radeon HD 7990 in Ubuntu 12.04 and above

yes it will be quad crossfire.Recommend,first to install driver,and activate driver with just one dual card(inside desktop).
when is just one dual card inside then last step of installation driver is:
sudo amdconfig --initial -f --adapter=all, but dont use that command if you have two dual cards already installed!

Then add 2nd card into motherboard,boot,and add crossfire chain ,and activate crossfire,and then reboot.Also check what crossfire speed yours motherboard support,regardless OS.

Be sure that IOMMU option if u have it in BIOS is disabled!
As with IOMMU =on ,both single and dual cards will not work in crossfire,regardless dual,triple,or quad crossfire ,its like that,for now.


How should I troubleshoot this weird SSD issue?

I have the same problem with my Dell Latutide E6530 and  ADATA SSD SX900 512GB.
It looks like a problem with disk controller and the cache.

I found some workaround.
Even if cache is on I enable it again by:

sudo hdparm -W1 /dev/sda

Very seldom (do not ask me why) it do not work so in this case I disable cache:

sudo hdparm -W0 /dev/sda

Did you check it out with any Windows? It should answer if it is hardware of software problem.


How can I make Ubuntu to run only one application on startup

I'd follow these instructions
How to run scripts on start up?

I think the easiest way is to figure out a terminal command that can run your program. Then from your dash search for startup applications. Click the add button. Copy the command where it says command and then save that.


Is Firefox going to support h264 tag on ubuntu?

When compiled with multimedia support, Firefox already does support H.264 (as I have seen on both Gentoo and FreeBSD) For this kind of support to arrive on Ubuntu would mean that one has to make it so that Firefox would install this support when installing the .deb file (by default, it is turned off)

So to answer your question: support may come sooner than you think! (There just has to be high enough demand for a .deb file with support already enabled in it)


How can I check the available version of a package in the repositories?

Use the command:

apt-cache policy <packageName>

This gives you information of all available package versions.

Example:

alaa@aa-lu:~$ apt-cache policy vlc
vlc:
  Installed: 2.0.8-0ubuntu0.13.04.1
  Candidate: 2.0.8-0ubuntu0.13.04.1
  Version table:
 *** 2.0.8-0ubuntu0.13.04.1 0
        500 http://ae.archive.ubuntu.com/ubuntu/ raring-updates/universe i386 Packages
        500 http://security.ubuntu.com/ubuntu/ raring-security/universe i386 Packages
        100 /var/lib/dpkg/status
     2.0.6-1 0
        500 http://ae.archive.ubuntu.com/ubuntu/ raring/universe i386 Packages

From the output, you can see that there are two versions available: 2.0.8-0ubuntu0.13.04.1 and 2.0.6-1. It also tells you which repositories they are coming from.
Installed: tells you the version you have installed. If you don't have the package installed, you'll see (none).
Candidate: is the version that will be installed if you use apt-get install vlc. If you want to install the other version, you would do apt-get install vlc=2.0.6-1.


What tools do you use to monitor a web server?

Nagios is my favorite tool for monitoring. It can monitor web servers,services,hosts and so on. It is highly customizable and there are lot plugins available for various purpose.

Some features of nagios:

Monitor network services (SMTP, POP3, HTTP, NNTP, PING, etc.)
Monitor host resources (processor load, disk usage, etc.)
Allow for simple plugin design
Do parallelized service checks
Define a network host hierarchy using
Contact administrators when service or host problems occur
Define event handlers to be run during service or host events for proactive problem resolution
 Automated log file rotation
Support the implementation of redundant monitoring hosts
Offer an optional web interface for viewing current network status, notification and problem history, log file, etc

Here is an online demo: http://nagioscore.demos.nagios.com/


boot-repair fails (UEFI and pre-installed Windows 8)

I did a quick look in the manual for the laptop and F12 (confirmed to be working) should have been the right key according to instructions for booting from external media. You should probably check the manual yourself.

UEFI firmware update

There is the possibility that the UEFI firmware of the laptop does something else than what is expected according to the output from efibootmgr -v.

BootOrder: 0006,0000,2003,2001
[...]
Boot0006* ubuntu HD(2,200800,82000,2f11f25e-4303-11e3-be2a-0c54a5038f2e)File(EFIubuntushimx64.efi

You should check if there is a firmware update available to update and check again after the update if it fixed your issue.

Per HDD-default UEFI bootloader

Another possbibility is that the default bootloader (\EFI\BOOT\BOOTx64.EFI on each HDDs ESP) is always booted (seems to be the case). Check if you can change this behaviour. A fully functional firmware should be able boot the ubuntu or  Windows Boot Manager entries (as seen in the efibootmgr -v output) instead of the default one. I found a related post in a blog.

My general advice is too back up \EFI\BOOT\BOOTx64.EFI and replace it. I prefer gummiboot (tested, works), rEFInd is also possbile. I don't know what boot-repair does or suggest for this.

This really seems to be a firmware issue and installing another distribution does not seem to improve on this (I also found a forum post for Fedora with a similar issue).

Suggested solution

You con only boot the \EFI\BOOT\BOOTx64.EFI file on a harddrive with this laptop, so you need to replace it with something, that can boot more than just Windows. Running boot-repair will not help or make confusion worse.

Get gummiboot

Download gummiboot from the Arch Linux repositories. (Everything is fine, we are just doing Linus Torvalds style package management. You can find the download link on that page far on the right under Package Actions > Download From Mirror)

Mount the EFI System Partition (ESP) and backup all existing files on the ESP (e.g. use zip or tar). You can put the backup file at the root of the partition, there should be enough space.

Extract gummibootx64.efi from the package (it's under /usr/lib/gummiboot/) and copy it as \EFI\BOOT\BOOTx64.EFI to your ESP.
Configure gummiboot to boot GRUB

Create folders along the path loader/entries/ at the root of your ESP and create a file named ubuntu-grub.conf with the following content:

title          Ubuntu GRUB
efi            \EFI\ubuntu\grubx64.efi

You also need to add the file loader.conf in loader/ to make gummiboot work.

default        Ubuntu GRUB
timeout        4

default is the title of the default entry to boot. Edit appropriately if you have chosen another title.
Reboot

That's it. Gummiboot will automatically find and create menu entries to boot Windows.


On my laptop, in the displays settings dialog, I have the ability to select either display, then turn it on or off with the switch under the graphic (ipod-style on-off switch).  If I turn off the one for the laptop, next time I boot, it will not display, even if the other monitor is not connected - I found this out the hard way, of course. :)

This is using the standard settings dialog with a default driver on an old Thinkpad.


Could not unmount /dev/sda1 with root filesystem

You can't unmount it, because it's being used. From the error message, /dev/sda1 is the location of your root directory /. Instead, create a gparted live CD, then boot from that. Then, you should be able to resize the (now-unused) root partition.

Make sure you back everything up before resizing!


NVIDIA drivers not working (Bumblebee and NVIDIA X Server Settings)

As you did not mention the Ubuntu edition you are using ... this is valid for all currently supported editions (12.04 | 14.04 | 16.04 | 16.10). Use this method to install the latest stable NVIDIA drivers !

First uninstall the currently installed NVIDIA drivers and bumblebee.
The solution to switch between the graphics adapters is nvidia-prime.

Boot the computer, mark the Ubuntu entry in the GRUB boot menu and  press the E key.
Add nouveau.modeset=0 at the end of the linux line. Press the F10 key to boot Ubuntu.

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

sudo apt purge nvidia* bumblebee
sudo apt install ppa-purge
sudo ppa-purge bumblebee/stable
sudo ppa-purge xorg-edgers/ppa
sudo reboot

Note : As I do not know which of the linked answers you tried, I just removed both PPAs ...
Now install the official NVIDIA drivers 375.26, which support NVIDIA GEFORCE GTX 840M.

Boot the computer, mark the Ubuntu entry in the GRUB boot menu and  press the E key.
Add nouveau.modeset=0 at the end of the linux line. Press the F10 key to boot Ubuntu.

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

sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt update
sudo apt install nvidia-375 nvidia-prime
sudo reboot

Important : Set a space between the last letter in the linux line and nouveau.modeset=0.
Switch between intel and NVIDIA graphics with NVIDIA X Server Settings -> PRIME Profiles.


The mysqld.conf file had collation-set-server = utf8 when it should have been character-set-server = utf8


How do I remove extra Skype icon or ghost icons for removed apps from GNOME shell?

It seems you have snap installed as per your reply to @Carl's question.

Installing Skype from two sources (snap and .deb) lead to some junk .desktop files after removing the snap package. You can solve this by cleaning up after removing the snap.

Check the /var/lib/snapd/desktop/applications/ directory for a skype_forlinux.desktop file or something with skype* in the name (or any .desktop file which may be associated to the application). If you find it, move it somewhere else (e.g. /tmp) and check again by searching though 'Activities'.

It should be fine now.


juju: can't add machines again after the destroy-machine command

The comma-delimited list of tags shouldn't have a space between them. Instead, try this:

$ juju add-machine --constraints tags=virtual,controller


Well, I will answer my own question with a dirty workaround. But at least it worked. I

Acquired a dead HDTV motherboard to connect a fake display via HDMI (one to the first VGA card, not all of them)
Installed TeamViewer (I really hate this, especially on Linux, but...) and made a remote connection
Opened a terminal with CTRL+ALT+T and issued these commands:

export DISPLAY=:0
./amd_fglrx_installer.run

went through the direct install method via the graphical installer (instead of building *.deb packages -> this is why SSH won't cut it and why I needed a graphical remote desktop)
Issued in the same terminal (where DISPLAY=:0 remained active, repeat the export command otherwise):

amdconfig --adapter=all --initial
reboot

After Ubuntu booted, cgminer sees every OpenCL device and can monitor/control them via ADL. It runs slightly better on the Ubuntu 14.04 nightly than it did on Windows 8.1 (higher GPU/RAM clock rates are more stable and I can use higher concurrency parameters without running out of the system RAM).

Note that I need to start cgminer in a terminal windows inside the TeamViewer graphical remote desktop and also issue the DISPLAY:=0 export in advance. It still doesn't work through SSH.

I am not sure if at least one of these steps are redundant but this is how I finally got it working. And to be honest, it's not exactly a headless machine now. I am not sure if I am free to remove the HDMI cable from the first VGA card now, or I need to keep that plugged in. I don't have the courage to mess everything up by trying. :)

I am still searching for a way to get rid of TeamViewer because it causes ~50% load on both CPU cores even when I do not connect any clients to the server. But xrdp doesn't seem to work at all with fglrx (I don't see the desktop, just a black background with an X as a cursor).

Also note that I used a nightly build. I think older stable versions will do just fine. I was just on a row of "try everything" and I ended up using this Ubuntu build when I accidentally got it working. You should consider that the latest stable driver from AMD I limited to kernel 3.11, and won't install with kernel 3.12, so I need to keep the earlier beta.


Mentioned problem is now fixed in the same nautilus package version 1:3.10.1-0ubuntu8. If you  still face this problem in Ubuntu 14.04 then update your nautilus package version from 1:3.10.1-0ubuntu8 to 1:3.10.1-0ubuntu9.

1:3.10.1-0ubuntu9 version of nautilus package is available at trusty-proposed repository. Follow this answer to enable trusty-prosed repository. After that update all the repositories by running sudo apt-get update command and install nautilus 1:3.10.1-0ubuntu9 package by running sudo apt-get install nautilus command on terminal.


server script that sends an email every time the global ip changes

Have you considered using dynamic DNS update script/tool?

e.g. ddclient available as Debian/Ubuntu package.

It can update your DNS zone OR update your dynamic DNS record (so you can ssh in) and execute custom script to send you email.


Cannot boot Windows 7 or boot from any bootable media

Likely what has happened is that GRUB is trying to find the formatted partition, but cannot. When this happens (I have personally experienced this) GRUB goes into rescue mode.

If it is possible to boot from a "Live CD" then you should boot so (into Ubuntu) and follow the following tutorial: https://help.ubuntu.com/community/RecoveringUbuntuAfterInstallingWindows

Yes, it does say it is for after installing Windows, but it serves this purpose perfectly as well.


Try this:
1.sudo apt-add-repository ppa:suraia/ppa  then
2.sudo apt-get update then
3.sudo apt-get remove gedit && sudo apt-get install gedit then
4.sudo apt-add-repository -r ppa:suraia/ppathen REBOOT and
5.gedit -V you should see the version of gedit.
idk if it really helps but try


What is IOMMU and  will it improve my VM performance?

So long story short, the only way an IOMMU will help you is if you start assigning HW resources directly to the VM. Just having it doesn't make things faster.

It would help to know exactly what Motherboard/CPU is advertising this feature.
IOMMU is a system specific IO mapping mechanism and can be used with most devices.

IOMMU sounds like a generic name for Intel VT-d and AMD IOV. In which case I don't
think you can multiplex devices, it's a lot like PCI passthrough before all these fancy virtualization instructions existed :). SR-IOV is different, the peripheral itself must carry the support. The HW knows it's being virtualized and can delegate a HW slice of itself to the VM. Many VMs can talk to an SR-IOV device concurrently with very low overhead.

The only thing faster than SR-IOV is PCI passthrough though in that case only one VM can make use of that device, not even the host operating system can use it. PCI passthrough would be useful for say a VM that runs an intense database that would benefit from being attached to a FiberChannel SAN.

Getting closer to the HW does have limitations however, it makes your VMs less portable for deployments that require live migration for example. This applies to both SR-IOV and PCI passthrough.

Default virtualized Linux deployments usually use VirtIO which is pretty fast to begin with.


installing pidgin - Package libdrm-nouveau1 cannot be removed

go into your package manager. I use the muon package manager and sometimes have had to select packages & to purge couple times or more to work, should be an option instead of uninstall.

Also try apt-get autoremove


Why do Upstart jobs use `start on runlevel [2345]`?

Yes they are used for compatibility with other distributions and the LSB PDA specifications.  I have had multiple systems in which runlevels 3,4,5 were used, but don't ask me what they were, this was years back.

If it bothers you, it shouldn't be an issue to remove those runlevels in all the configurations, but I would recommend leaving it as is.  If it ain't broke, don't fix it.


Here's what I do to get python support in vim

apt-get install -y python-software-properties software-properties-common

add-apt-repository ppa:pi-rho/dev

# add this repo so that vim has python 4? compiled in to support plugins like gundo
add-apt-repository -y ppa:pi-rho/dev
apt-get update

install vim-gtk

this install a massive vim build that will give you everything

apt-get install -y vim-gtk

Running these commands on Ubuntu 16.04 worked for me about 2 weeks ago.

problems with versions

The way this can cause problems is that by default, apt-get will install the newest version of the package, usually the pi-rho repo version is far newer than say 14.04's vim-gtk package and apt will install the pi-rho version. However on 16.04 the ubuntu universe? repo for vim-gtk has been neck and neck for versions with pi-rho - but the ubuntu package doesn't seem to have python support. ( I may be wrong on this though ).
so ideally you would run

apt-cache policy vim-gtk

prior to install to check that apt will install pi-rho, if not you will have to run something like

sudo apt-get install vim-gtk=<version>


TL;DR:

Where is login shell defined? In /etc/passwd.
Are sudo su/sudo su -/sudo -i/sudo -s same ? No, they all spawn a shell but differently and in different contexts.
What does $SHELL do? Just tell your default shell, same as in /etc/passwd.

Actual Answer:

First of all, it's important to mention that shopt is bash-specific. For instance, I am mksh shell user, and it doesn't have shopt , just like ksh doesn't.

Next, what exactly login_shell is supposed to represent ?  From man bash:

  login_shell

  The shell sets this option  if  it  is
  started  as a login shell

That's the key point. sudo -i , as you already know from previous answer you read, is supposed to simulate initial login. That's why shopt reports login_shell on  for this option. Think of this as if sudo -i forces the shell to go through files that are supposed to appear only during a login process ( which don't get sourced by interactive shells).

In other cases, you already are running an instance of a shell, so it cannot be login shell in the first place, and the purpose of the options is different. sudo -s merely reads $SHELL (which is meant to represent your default shell as set in /etc/passwd) variable and runs it with  root privilege.  This is equivalent to doing sudo $SHELL or sudo mksh or sudo bash ( whichever you happen to use).

Remember I mentioned that I am mksh user ? Take a look at this:

$ bash --posix
bash-4.3$ sudo -s
[sudo] password for xieerqi:

DIR:/xieerqi|01:53|skolodya@ubuntu:
$ id
uid=0(root) gid=0(root) groups=0(root)

DIR:/xieerqi|01:53|skolodya@ubuntu:
$ echo $-
imsU

What you see is that sudo -s jumped from bash to my mksh shell, with the characteristic prompt I've set for it. And of course, since it is not a login action, for bash it would report that the shell is spawned as non - login shell instance. In my case, however, you see that $- doesn't have a letter l there, which would be there if that was a login shell instance.

Finally, the same idea applies to sudo su and sudo su -. Later one spawns login shell instance (i.e., specific files that are required for login will run) and former one spawns only interactive shells (i.e., login files don't run).

bash-4.3$ sudo su
[sudo] password for xieerqi:
root@eagle:/home/xieerqi# shopt login_shell
login_shell     off
root@eagle:/home/xieerqi# exit
bash-4.3$ sudo su -
[sudo] password for xieerqi:
$ shopt login_shell
login_shell     on

So technically, shopt login_shell has no relation to $SHELL whatsoever. Think of it this way: its purpose is to show how bash runs. $SHELL is supposed to reflect only what you have assigned in /etc/passwd.

As for the difference between login shell and non-login shell, it has been explained by highly-respected Gilles on unix.stackexchange.com in this answer.

Additional fun

Here's  something fun you can try. As you may already know, a login shell will run .profile (and .bashrc since Ubuntu's .profile is configured to do so) , but non-logins hell will run only .bashrc file. So we can test with echo which of these commands runs a login shell and which doesn't, and we expect two lines of echo for login shell and only one for non-login.

$ echo "echo 'hi,i am .profile'"  >> .profile
$ echo "echo 'hi, i am .bashrc'" >> .bashrc
$ sudo -i
hi, i am .bashrc
hi,i am .profile
$ sudo su
hi, i am .bashrc
root@eagle:~# sudo su -
hi, i am .bashrc
hi,i am .profile
$ sudo -s
hi, i am .bashrc
root@eagle:~#

Appropriately enough, those with two lines of output will have login_shell set to on.


How to set the minimum time between double clicks?

In Ubuntu go to Settings → Universal Access → Pointing and Clicking

and adjust the delay to what you require.


The Package System is Broken after Upgraded to Ubuntu 17.04

I think I found a solution, but a big caveat though: it works, but I can’t explain why.

First, I went to /var/lib/dpkg/info/:

cd /var/lib/dpkg/info/

Then, I removed the lines pertaining to the packages which caused the problems. In my case, I had to do:

sudo rm -r python3-apparmor-click.*
sudo rm -r click-apparmor.*
sudo rm -r click.*
sudo rm -r ubuntu-app-launch.*
sudo rm -r url-dispatcher-tools.*
sudo rm -r url-dispatcher:amd64.*
sudo rm -r libunity-scopes1.0:amd64

After that, I typed:

sudo apt purge python3-apparmor-click
sudo apt purge click-apparmor
sudo apt purge click
sudo apt purge ubuntu-app-launch
sudo apt purge url-dispatcher-tools
sudo apt purge url-dispatcher:amd64
sudo apt purge libunity-scopes1.0

After that,

sudo apt update

And finally,

sudo apt dist-upgrade

which worked and updated my packages. All the packages problems seem to have disappeared.


Removed Python 3 and now Ubuntu Software Center, terminal and other applications don't work

Open a text-only virtual console by pressing the keyboard shortcut Ctrl + Alt + F3.
At the login: prompt type your username and press Enter.
At the Password: prompt type your user password and press Enter.
Reinstall the default Python 3 version by running the following command:

sudo apt-get install python3-all

Switch out of the virtual console and return to your desktop environment by pressing the keyboard shortcut Ctrl+Alt+F7. In Ubuntu 17.10 and later press the keyboard shortcut Ctrl+Alt+F2 to exit from the virtual console.

After you have installed the default Python 3 version, you need to get back your default Ubuntu desktop system. In order to avoid messing something up, do it in the following order:

First install the terminal from the console using the command: sudo apt-get install gnome-terminal. If you can't install gnome-terminal at all, skip this step and go to step 2.
Return to your desktop and open the terminal using the keyboard shortcut Ctrl + Alt + T. From the terminal install the Ubuntu Software Center using the command:

sudo apt-get install software-center

In Ubuntu 16.04 and later run this command instead to reinstall the  default Software application:

sudo apt-get install gnome-software

If you still can't open the terminal, run the same command from the console instead. If you can't install the default software application at all, skip this step and go to step 3.
Open the terminal and try to open the Ubuntu Software Center from the terminal by running the appropriate command, either software-center or gnome-software. From the Ubuntu Software Center install the Ubuntu desktop system or else open the terminal (or the console) and install the Ubuntu desktop system by running the command: sudo apt-get install ubuntu-desktop.


Please install the latest driver (both kernel and xorg parts) shown in this help file:

https://help.ubuntu.com/community/Wacom/LatestDriver

For example:

sudo add-apt-repository ppa:doctormo/wacom-plus
sudo apt-get update
sudo apt-get install wacom-dkms xserver-xorg-input-wacom

This should install the latest driver for both maverick and lucid. If this doesn't work then let me know and I will look into upstream and if needed, update this driver for you.


mount.cifs hangs and becomes unresponsive

This problem has been around for at least 10 years, and there still seems to be no way to fix it. I've tried umount -l xxx, which doesn't hang, but then we do hang when trying to mount the share. One problem seems to be that you need to remount the share before any process tries to open a file on it. This can be very tricky if you have soft-links pointing into the shared file system.

Even crazier: If the system is stuck, smbmount still works without a hitch, even as the mount on the same volume is hung for more than 10 minutes.


Dynamic resizing of screen doesn't work in Parallels

The version of Parallels Tools that comes with Parallels 7 doesn't support Ubuntu 12.10, but it's possible to install the version that comes with Parallels 8.

If you download the trial version of Parallels Desktop 8 and mount the disk image, you'll find the Parallels Tools ISO at /Volumes/Parallels Desktop 8/Parallels Desktop.app/Contents/Resources/Tools/prl-tools-lin.iso. Mount this ISO in your Ubuntu VM and follow the usual instructions to install/upgrade the tools.

("Parallels Desktop.app" is flagged as hidden and doesn't appear in Finder, but you can still copy the ISO out of the disk image using terminal.)

I did this with my Ubuntu 12.10 VM on Parallels 7 and dynamic screen resizing works fine.


You can also use folder-colors, a Nautilus extension which enables you to add a color shade to a specific folder. The same folder icon but just in different colors.

Here’s the PPA which you should add to your system repositories through a terminal:

sudo add-apt-repository ppa:costales/folder-color

sudo apt-get update && sudo apt-get install folder-color

More information on OMG! Ubuntu!


pCloud Desktop does not save credentials

I logged into pCloud website from my browser and that seems to have fixed the issue. The desktop app now is logging in automatically.


small GTK user interfaces on HiPDI display

I have the same machine.

I think you're likely out of luck. HiDPI support is far from perfect in any distro. I've found that applications that use the GTK3 UI framework look good on HiDPI screens but applications using the older (but more prevalent) GTK2 framework look poor. I don't think there's an easy fix for it other than getting the developers to update their apps to a more modern framework.


Adobe Kuler to GIMP importer or Converter

You can find a GIMP plugin here:
http://registry.gimp.org/node/10325


Edit: I skipped right to the end of the question and hadn't noticed you were trying to log in with a normal user account to begin with. The following explains why remote root login doesn't work by default in Ubuntu. Either way, it seems to have helped.

For the normal user stuff, just look in /var/log/auth.log. It'll tell you exactly what the problem is and that should give you a fairly decent idea of what you need to do.

But for root issues, there's a little block in /etc/ssh/sshd_config.

# Authentication:
LoginGraceTime 120
PermitRootLogin without-password
StrictModes yes

That's the default and it means it'll only allow SSH key based authentication for root.
It won't allow you to log in with a password.

Obviously you could change the setting to yes but you're starting to unravel the security of Ubuntu. Having a working root login (especially with a super-crackable password) is usually a pretty awful (and unnecessary) idea. It would be easier to just use a SSH key.


How to recover windows partitions lost during Ubuntu installation

That is correct, you need another disk to store the recovered files that the software is able to find on the disk, because writing to the same disk would cause more technical difficulties in the recovery process by overwriting other data also should have been recovered.

With modern spinning disk hard drives the consensus is that what has been overwritten is lost. So the sectors which contained data that have been actually overwritten by the installation of a new operating system should be considered definitively lost, the other data might be recoverable.

You should always have more than one hard drive when handling different operating systems or performing non-reversible commands and also heed the warning messages and notices (there was at least one when you did that). You should also have verified backups, that is at least 3 copies of a file and you know that it has the content and consistency you need.


The solution is to read the error message: are you root?. Use sudo to run a command with root privileges, like so: sudo apt-get update


BIG desktop glitches with Ubuntu 16.04 and AMD

I've seen incredibly similar issues caused by not having the right drivers installed - highly recommend finding an AMD driver for your card. The drivers are available from:

http://support.amd.com/en-us/download/desktop/previous/detail?os=Ubuntu%20x86%2064&rev=15.9

The driver comes with full installation instructions if memory serves, and you should be up and running in no more than 30 minutes with your desktop looking normal again.


cannot install my hp printer with hp-setup

Test this:

Connect printer with the computer and turn it on.

Open a terminal,Press Ctrl+Alt+T

Run it:

sudo -i
apt-get update
apt-get install --reinstall hplip printer-driver-hpijs printer-driver-hpcups openprinting-ppds printer-driver-postscript-hp cups cups-filter printer-driver-gutenprint
hp-setup -i

Once you press enter, the automatic installation will download the needed packages for the hardware. Let the installation finished. Make sure that the printer is connected along installation process.

Once you finished the installation, you can try to print and scan using the device. The installation will download the proprietary package from HP repository. You can try to check the printer configuration once after installation finished. Using HP LIP, you can also try to run the basic HP printer and scanner utilities to make sure that all devices are running correctly.

Source: http://www.openprinting.org/printer/HP/HP-HP_LaserJet_Professional_M1132_MFP


unable to mount filesystem: not authorized

try mounting using gparted parttion manager

to install gparted

sudo apt-get install gparted

try posting output of

sudo fdisk -l


What would I have to do to get WNA3100v1 drivers on Xubuntu 14.03?

I suggest you download these files on to the USB drive: http://mirrors.kernel.org/ubuntu/pool/universe/n/ndiswrapper/ndiswrapper-common_1.59-2_all.deb and also, if yours is a 32-bit system: http://mirrors.kernel.org/ubuntu/pool/universe/n/ndiswrapper/ndiswrapper-utils-1.9_1.59-2_i386.deb Or 64-bit: http://mirrors.kernel.org/ubuntu/pool/universe/n/ndiswrapper/ndiswrapper-utils-1.9_1.59-2_amd64.deb

Confirm:

arch

A 32-bit system will report i686; 64-bit will report x86_64.

Also download the driver files at post #89 here: http://ubuntuforums.org/showthread.php?t=1695036&page=9

Transfer all from the USB to the desktop of the Ubuntu machine. Install the .deb files first:

cd ~/Desktop
sudo dpkg -i ndis*.deb

Note and post any errors.

Right-click the Broadcom file and select 'Extract Here.' Now back to the terminal:

cd ~/Desktop/Broadcom_bcm43xx_USB_32_64bit_v2_amended

If yours is a 32-bit system:

sudo ndiswrapper -i bcmn43xx32.inf

If yours is a 64-bit system:

sudo ndiswrapper -i bcmn43xx64.inf

In both cases:

sudo ndiswrapper -ma
sudo modprobe ndiswrapper

Your device should now be working.


When asked for the password the second time, the D-Link modem-router is asking you for its password.  You'll have to find that password in order to continue and connect.


First you need to delete expired GPG key.
sudo apt-key del 4FE13824E3FFC656

Install latest GPG Key for Brave Browser repo, after you will be able to update it.
curl -s https://brave-browser-apt-release.s3.brave.com/brave-core.asc | sudo apt-key --keyring /etc/apt/trusted.gpg.d/brave-browser-release.gpg add -


Why do Windows files moved to Ubuntu NAS disappear?

This is probably a permissions issue. To check, run the command sudo ls -la in a folder that has Windows files. You should see your missing files. (The sudo command uses the "super user" account, which has authority to almost everything.)

If so, the problem is that samba is not assigning the correct default permissions to new files. There is a setting in smb.conf that defines the default permissions for new files.


How do I merge 2 VMware disks in to a single one?

It should be possible to resize you VMware disks, instead of adding an extra one, with the installed tools from VMware.

To expand a existing disk use the command:

vmware-vdiskmanager -x 1000GB myDisk.vmdk

where 100GB is the new disk size and myDisk.vmdk is the disk file for your Ubuntu server installation.

Next time you boot your vm the partition size will still be the same, you need to expand it to the new available space.

To check where your  / is mounted use the command mount, it will return a line similar to:

  dev/sda7 on / type ext3 (rw,noatime,nodiratime)

once you know where your / is mount you can use the command resize2fs as such:

resize2fs /dev/sda7

After the resize is finished you should to a file system check (not recommended while the device is mounted). Of course with any disk operations a disk backup is recommended.

By the way, you should be able to download the Ubuntu LiveCD for desktops and use it in your VM by booting the iso, that does not destroy your current setup and might make you life easier while repartitioning.


How do I install RTL8821AE driver for Ubuntu 20 LTS

If you are looking for an equivalent repository you should look into rtlwifi-linux/rtlwifi_new
It throws some warning-errors and I couldn't compile it.
NOTE: rtl8821ae driver is supported in linux kernel version 3 and newer, but not working properly in my case.


I changed my account from Administrator to Standard. How can I reverse this?

I tried to follow reverendj1's instructions (See above?  Below?  Every time I refresh this page, the articles swap positions), and they didn't work for me on Ubuntu 12.04.1.  I had two issues:

1) Simply booting into recovery mode apparently mounts your root partition as read-only, so you can't modify any system files.  Another page addresses this, you need to execute this command from the root prompt in order to obtain write privileges:

mount -o remount /dev/[your root partition]

2) But even after I had write privileges, the useradd -G command wasn't working for me.  When I tried to execute it, the system would just return the help screen for the useradd command.  I don't know why.  But I decided to use usermod -aG instead, and that worked.  I added my user name to each of the 16 groups in reverendj1's instructions, one at a time.  I was being conservative, I saw some error messages I didn't understand when I was experimenting with useradd.  Afterwards, I looked at the man page for usermod, and it looks like you could just list the 16 groups all at once, tacking on the user name at the end.

Here's how you can double-check that you did everything correctly.  Compare the output of the following command, before and after you make changes:

more /etc/group

You should see that your user name has been added to the groups you specified.


Compiz already has this in the form of the bicubic filter plugin.


I had lots of problems trying to share a Canon printer attached to my Ubuntu desktop, similar to what you stated.  Jobs look like they print, but never did.  The easiest solution was to install Google Chrome and use its cloud printer feature.  Then on the Windows side there was a Google Cloud printer app.  Also worked well for printing from my Android devices.  In my smb.conf file, I commented out all references to printers so they would not show up on the Windows PCs.


System won't shut down properly, stays in the plymouth screen

I am running Ubuntu 13.10 on my Surface Pro (with touch cover) and I am facing the same problem (which I fixed!)

the shutdown -h now command works after a while, it gets stuck there for 2 or more minutes, my guess is that it forces the shutdown/reboot, which is not good.

The problem is that network-manager does not quit when the signal for KILL is passed to it. You have to stop it before rebooting/shutting down:

I have created a bash script called K99_stopnm on /etc/init.d sym linked under /etc/rc0.d/ and /etc/rc6.d/ as K99_stopnm_sm and it works great, if you press the down arrow when you get the ubuntu splash screen on either reboot or shutdown, you will see this:

shutting down network manager

network-manager stop/waiting
network manager is down

my script looks like this:

#!/bin/bash

echo "shutting down network manager";

stop network-manager;

echo "network manager is down";

sleep 2;

hope this helps and I hope the Ubuntu team can fix this anytime soon

thanks


No sound icon on the top Unity panel in Ubuntu 12.04

1

If you are on a laptop, the sound icon will disappear when you reboot with the volume on mute and it will usually return if you use the fn buttons to adjust the volume.

Another way to remedy this type of situation is to bring up your system settings to change the volume from there.

2

Next, check to see you have a file under "/etc/pulse/default.pa". if you do not have this file, you need to download a copy of default.pa see the answer to this post: How to make pulseaudio work again? Reboot after you replace the file.

3 (Accepted Answer)

Finally, check to see if or reinstall "indicator-sound" and "pavucontrol" and maybe the indicator applet packages as well.

Also, if I remember correctly, there should be a panel volume control in "software center" but I've never had that prob in 12.04 yet


E: py3compile:243: Requested versions are not installed

py3compile file is provided by python3-minimal whose default version on Xenial Xerus is 3.5.1-3 and according to Ubuntu Package search, it depends on python3.5-minimal but you have python3.7-minimal installed and default python3 set to python3.7 which is a very bad idea. Python is an integral part of Linux system and default Python shouldn't be touched unless you're experimenting things and in mood of corrupting system.
You need to restore default Python 3, which 3.5 for you, by installing python3.5 minimal package and changing symbolic links. To do that, run:
sudo apt install python3.5-minimal
sudo ln -sf /usr/bin/python3.5 /usr/bin/python3

Also, the order in which paths are given in PATH variable also defines priority. You may consider moving custom path to the end by modifying ~/.profile and changing
export PATH='/home/linuxbrew/.linuxbrew/bin:/home/linuxbrew/.linuxbrew/sbin':"$PATH"

to
export PATH="$PATH":'/home/linuxbrew/.linuxbrew/bin:/home/linuxbrew/.linuxbrew/sbin'

Logout and relogin to make changes take place. Run
sudo dpkg --configure -a

and retry the installation of packages mentioned in the question.


How do I fix "no setup signature found" error on install

Are you using a UEFI system? If yes, then you will need to disable the Secure Boot Option from the BIOS.
A link similar to yours -

no setup signature found

Another link-

from linuxmint forums

Couldnt find much on the net about it.
Try upgrading to Grub 0.97 , it solved the problem for the person who posted earlier.(in the linux mint forums); or you could upgrade to Grub 2 also.


Gnome Freezes often - how to find logs of the crash?

I found the culprit is gconnect (Gnome extension to use KDE connect with my android phone). Seems like notifications from my phone that are relayed to my computer, cause it to hiccup and is what is causing the crashing. Shame.


I'll see that this Question is already kind a old.
But if you still facing this Problem, then this might fixes it.
If you installed Wine correctly from the offical WineHQ Website like followed the Instructions right, then you normally already can download an executable file and you can right click it or Open File with and select then "Open With Wine Windows Program Loader" and normally it should work then. That was actually for me so. So i am not pretty sure, if this will works also for you. But i hope so. I am currently on Linux Minut, but Linux Mint is the same as Ubuntu, so it doesn't matter.


most of apt not working. (caused by wine packages)

I managed to fix this

But I spended a few good hours (about 4 with other methods)

get synpatic from here: https://ubuntu.pkgs.org/17.10/ubuntu-universe-amd64/synaptic_0.84.2_amd64.deb.html

download it with the dependencies.

cd ~/Downloads

sudo dpkg -i synaptic(version).deb
and same goes for the dependencies.

Use the broken filter within synaptic. And just remove all of it in my case.


Ubuntu 16.04 Microfreezes ca. every second

So edit after some time:
I have now upgraded to Ubuntu 18.04 and the freezes are gone. I never got rid of them completely in 16.04, but I found that part of the problem was RealPlayer (a browser add-on to download videos). I deinstalled it and the freezes got less pronounced, but they didn't completely dissapear.

Anyways... Ubuntu 18.04 seems to be more compatible with HP Omen, than 16.04.


Unable to create file in specific folder

Most directories under /etc will require root privileges to create files in.  Unfortunately, the default file browser doesn't provide a quick-n-easy method to escalate privileges for a single operation.  The command line is your answer.

sudo nautilus will launch a copy of nautilus w/ root privileges, allowing you to do whatever you want.  I'm not sure that's a good idea (easy to leave it open and forget that it has super powers), but it's convenient in some cases.

sudo touch /etc/apt/preferences.d/cloudera.pref will create an empty file. Once you've done that, you could do something like
sudo chown some_user /etc/apt/preferences.d/cloudera.pref to change ownership or
sudo chmod a+rw /etc/apt/preferences.d/cloudera.pref to open read/write privs to everyone (generally a bad idea)
You can also set user & group on a file at the same time:

sudo chown some_user:some_group /etc/apt/preferences.d/cloudera.pref

or just set the group ownership:

sudo chgrp some_group /etc/apt/preferences.d/cloudera.pref

an ls -l (or using your graphical browser w/ the right settings) will display the ownership/permission details for verification.

You could create the file and set it to be owned by your user for temporary convenience, edit it using your convenient GUI editor if you want, then set ownership back to root or whatever you want it to be for proper security.

Typically, /etc contains static configuration files, so you make them readable by certain groups of users (even all users, if not sensitive) but reserve write privs for root.  I don't know anything about Cloudera, but it's common to have software running under a particular user (and a user can be a member of multiple groups) so you can set the group of the file to be the group that you want to have privs on it.


Move only the last 8 files in a directory to another directory

You can use for, which loops over the files in an ordered way, and allows us to avoid parsing the output of find or ls, to avoid issues with spaces and other special characters in filenames. Many thanks to @muru for improving this :)
i=0; j=$(stat ~/Documents/* --printf "%i\n" | wc -l); for k in ~/Documents/*; do if (( (j - ++i) < 8 )); then echo mv -v "$k" ~/AnotherDirectory; fi; done

Test it first with echo, then remove echo to actually move the files.
As a script:
#!/bin/bash
i=0
j=$(stat ~/Documents/* --printf "%i\n" | wc -l )
for k in ~/Documents/*; do
  if (( (j - ++i) < 8 )); then
    echo mv -v -- "$k" ~/AnotherDirectory
  fi
done

again, remove echo after testing to move the files for real
Explanation

i=0 telling the shell to start iterating at 0
j=$(stat ~/Documents/* --printf "%i\n" | wc -l ) this is setting the variable j to an integer equal to the total number of files in the directory. Thanks to Serg's answer to my own question on how to count files reliably no matter what characters their names contain
do if (( (j - ++i) < 8 )) for each iteration of the loop, test whether the outcome of j minus the number of times the loop has been run is less than 8 and if it is then
mv -v -- "$k" ~/AnotherDirectory move the file to the new directory


How do I make MIDI playback work on a Inspiron 531s?

Normally you won't be able to play back midi by default. Install ubuntu-restricted-extras (should pull in everything), and then try again.

You may also need to search for sound fonts in synaptic and install a package (you will need fluidsynth - but I think this gets pulled in by the package I mentioned earlier).


How do I change which firmware is used for my wireless card

The firmware version that is requested is written into the driver code. As you can see, the particular version if iwlwifi that you are using requests -16 firmware. You can load several different ucode files into /lib/firmware and the driver will call the version it was written to require.

NOTE: In some cases, there is a mismatch between what the driver code seems to require and what actually loads.

You could install a later version of iwlwifi; generally, this is done by installing a newer Ubuntu version. In Ubuntu 17.04, modinfo iwlwifi says:

filename:       /lib/modules/4.10.0-22-generic/kernel/drivers/net/wireless/intel/iwlwifi/iwlwifi.ko
license:        GPL
author:         Copyright(c) 2003- 2015 Intel Corporation <linuxwifi@intel.com>
description:    Intel(R) Wireless WiFi driver for Linux
<snip>
firmware:       iwlwifi-8000C-26.ucode
<snip>

The corresponding linux-firmware package contains -13, -16 and -21; but not -26!

You certainly can upgrade your firmware. In any case, the driver will load the firmware file it is written to require. In many cases, the driver will be written to use any of several versions; for example, -6, -7, -8 or -9. The driver looks for the newest it can find in /lib/firmware and, if it fails to find it, loads the next newest and so on. In the 'for instance' I give above, if the newest firmware package contains -6, -7, -8, -9 and -10, no harm will be done. The driver simply loads the newest and latest it is written for and ignores the rest. -10 will not load.

To upgrade yours:

wget http://mirrors.kernel.org/ubuntu/pool/main/l/linux-firmware/linux-firmware_1.164_all.deb
sudo dpkg -i linux*.deb

If your desire to load newer firmware is motivated by a wireless issue, we'd love to hear it and try to help.


How do you compare Ubuntu Server to Snappy Ubuntu Core?

No. Even though, Snappy is Ubuntu and completely compatible with other Ubuntu installs you will not be able to install and run pre-packaged applications.

Snappy introduces transactional updates and moves away from the repository paradigm. Meaning there are very few packages out there for Snappy currently, given its short existence. It also sports a read-only file-system in two partitions in order to be able to do quick roll-backs.

That is also the only difference between Ubuntu Server and Snappy. Snappy is really only a way to update and/or extend your system, it fills the function of apt-get. Here's Mark's explanation as to what Snappy really is. However, Snappy is mostly released and marketed in connection with Ubuntu Core as a base OS. When you download images referring to Snappy, it will be with Ubuntu Core as a base.

  Ubuntu Core is a minimalist Ubuntu installation. It existed before and without Snappy, but it seems that Ubuntu Core and Snappy are
  becoming the same thing. The Ubuntu Core website is now a link to
  Snappy. Anyways, here's some basic info

In addition, the arm architecture has even fewer alternatives as of right now (I'm assuming this is relevant to you, if you're going to run it on SBC). On my armhf based install (on a beaglebone) there are currently around 20 different applications available for install. However that is a 15.04 beta install. I am unsure if you are able to install Snappy on older stable Ubuntu Core installs, and whether that will give you more options.

Canonical's Dustin Kirkland has a great write-up about what use-cases Snappy Ubuntu covers here.


How to install Dual OS, Ubuntu 16.04 with Window 10

If the Ubuntu install process doesn't detect your Windows installation you can't use the Install Along Side Windows option.  You would have to use the do something else option.

On the Do Something Else option you can choose the drive or partition where you want to install Ubuntu.  For this you would have to manually create or provide the partition where you will be installing Ubuntu.  I would recommend the partition be at least 50 Gigs.  I would also suggest that you have a swap partition 10-15 gigs.

Now choose the Do Something Else and specify the partition you created for your Ubuntu installation.  This should be an ext4 type partition.

On the set the partition to /.  Formatting it is optional if you already have it formatted in the ext4 type.

Pick the drive you want to specify as the boot drive.  Unless you change something in your bios the computer will boot to the first drive which is /dev/sda.

The install will only touch the partition that you specify for the install.  After the installation is completed it will reboot and give you a menu option to choose which OS to boot to, with the default being your new Ubuntu installation.

Manually Creating Partitions on your Drive

You can use gparted on from your Live Ubuntu install USB drive to partition your disk.  You can get to this by choosing the Try Ubuntu when you boot to the install USB.  Click on the Launch button and type gparted to get to it.


Are there any packages in Ubuntu that allow routing on application layer level?

You mention URLs so forgive me if I make an assumption that this is web traffic. Could you put an apache + mod_proxy on the domU / VM host and direct the traffic based on URL that way?


Screen brightness (neither fn button or system settings/ brightness and lock do not work)

I'm Linux Mint XFCE User, and I use xfpm-power-backlight-helper to setting the brightness. Maybe this is help you, at least for reference, because it depend on Desktop variant. Different desktop, different tool.

To use this tool via command-line :

$ pkexec --user root xfpm-power-backlight-helper --set-brightness 20

or you can install xbacklight and here is how to use it

$ xbacklight -set 20

Here the link for further info about xbacklight


How to open programs found in Software Center?

Two things you can do:

Open Dash by either accessing it with a mouse click at the top left of your screen or by simply pressing the 'Windows' key on your keyboard. Then type in 'Software & Updates', this will open it up for you...
Now right click on the icon at the left of your screen that represents 'Software & Updates' and select 'Lock to Launcher', this will keep the icon on the Launcher for easy, future access

Screenshot here to demonstrate the 'lock' process:


installation 14.04 - Machine does not restart - stopping early crypto disks ok

See this answer:

What is ubuntu 14.04 doing while showing "stopping early crypto disks"?

I killed the VM, went into (for that VM) Settings | System, and removed the Floppy (!) and CD/DVD from the boot order (leaving just Hard Disk). After that I haven't had this problem again.


How to fix bangla fonts problem in firefox?

Do the following steps (for Ubuntu 16.04):

Click on  icon at top-right corner of the screen.
From this, choose System Settings...
Click on Language Support under Personal section.
A window would pop up. Click on the Install / Remove Languages ... tab. A list of languages will be displayed. Pick Bangla and check the box against it -- click Apply. It may ask for the administrative privileges again -- type in your password.
Wait until it finishes install.
When finished, Click Close
Restart your PC.

In my case, it fixed the issue. Tell me whether it fixes yours too or not.


Problem : Computer shutdown automatically without asking after ~15 minutes on

From the comments...

After reviewing the syslog with:

grep -i -e temp -e therm /var/log/syslog*

It's confirmed that your computer is severely overheating. The goal would be in the 50-60 Celsius.

I never received an answer if this was a laptop, or desktop, and its age, so I'll have to make some assumptions. Each of the following steps should be performed in < 10 minute steps, followed by a controlled system shutdown so as to keep the machine from burning up.

open the machine and clean out any dust, especially from the fan and CPU areas
install thermald

In terminal...

sudo apt-get update
sudo apt-get install thermald

if you've got Intel processors, check for, or install intel-microcode

In terminal...

sudo apt-get update
sudo apt-get install intel-microcode

enter the BIOS and note its version number, and then using the make/model #, check the manufacturers web site for a BIOS update. Apply it if it's newer.
If you have the technical experience, clean and re-apply thermal paste between the CPU and its heat pipe or fan assembly. This requires previous experience, so if you don't have this experience, please get technical assistance.


This might be a permission issue on the current directory you were working on.
And the file you created is not your ownership since you send a sudo command on it.

Try to check your current directory's permission.

If you don't have permission to it you can have

$ sudo chmod -R 755 Your_Directory/

or

change the ownership of that directory.

$ sudo chown -R user Your_Directory/

Next time you create a file just type

$ emacs "Your File in Here"


I'm not at a Ubuntu pc right now, but I'm trying to help out.

If I'm not mistaken boot logging is disabled by default.

In  /etc/default/bootlogd set

BOOTLOGD_ENABLE=Yes

Now, each boot entries in /var/log/boot will be created in a file that's readable by root (so sudo is needed). If I'm not mistaken this log is rotated so you'll have older versions.

If that won't work or you're not in /etc/sudoers, you can also try to boot with a bootable usbdrive and check the bootlog after a failed boot or boot into safe mode and redirect dmesg into a file using the output redirection operator:

dmesg > bootmessages$(date +%Y%m%d).bak


You need to change the theme, not the settings. So in /usr/share/plank/theme/<themename>/dock.theme you' ll find two entries:
#The padding on the bottom dock edge, in tenths of a percent of IconSize.
BottomPadding=2.5
#The padding between items on the dock, in tenths of a percent of IconSize.
ItemPadding=2

Change the padding until it fits your needs


Try on a terminal:

sudo update-manager -d


How to delete files and subdirectories by size and age?

Your original question is "How to delete files and subdirectories by size and age". Use find:

This will delete all files under the current directory larger than 2 MB:

find ./ -size +2M -delete

This will delete all files created more than 7 days ago:

find ./ -ctime +7 -delete


Gnome-panels take a long time to load on startup

I have the same issue. .xsession-errors isn't especially interesting. Watching top -- use ctrl-alt-F3 (or anything but F7, actually) to access a shell -- shows a lot of stuff booting up. In my case, Munin uses a lot of resources (so I'm looking into disabling it). Liferea takes its sweet time (so I'm wondering if there's a way to throttle that) and Ubuntu-One is busy busy.

I see other programs as well, including Conky, but I do want them on startup so i don't see a way around that.


Appmenu indicator places drop down duplicates nautilus bookmarks

It is something that bug me too.
I resolved by manually removing ( i.e. delete ) the duplicates from nautilus.

Open Nautilus, select the place from the sidebar, hit [Delete]


GVim no longer launches from Unity after customizing .desktop file

I finally settled on using gvim --remote-silent "" %F as the command in the .desktop file.

Opening files from Nautilus works as expected, all files open in the same instance of GVim.

Adding the "" before the parameter allows GVim to open from the Unity launchbar with the following error message.

This obviously is not perfect but it works for my purposes.


Ubuntu 18 What is my Desktop and how to get Xorg

1. To get available session managers, go with:

sudo update-alternatives  --display x-session-manager

2.To get available window managers, go with :

sudo update-alternatives  --display x-window-manager


How to hide Kubuntu apps from the Ubuntu desktop environment and the opposite?

You can edit the .desktop launcher associated to each application and add OnlyShowIn or NotShowIn keys accordingly. The .desktop files can be found in /usr/share/applications/ (and some in ~/.local/share/applications/).

But it's not recommended to edit the files in /usr/share/applications/ (they'll most likely be overwritten once an associated package gets updated). Instead copy the .desktop file from /usr/share/applications/ to ~/.local/share/applications/ and edit the copied file.

To make an application visible only in GNOME add the following line

OnlyShowIn=GNOME;

and to make an application invisible in GNOME add the following line

NotShowIn=GNOME;


Moving a single MySql database to a separate physical disk

Fixed it!

The issue was the apparmor entry:

/path/to/new/location/ r,
/path/to/new/location/** rwk,

actually needed to be one directory up from what it was:

/path/to/new/ r,
/path/to/new/** rwk,

EDIT
Ubuntu 18.04 required me to change the owner of the symlink to mysql:

(in /var/lib/mysql:)

chown -h mysql:mysql zm


new installation appears to have got stuck

Maybe start the installation from scratch and skip the ubuntu one part for now...


Give ftp users access to directories outside their root using symlinks

Symlinks are locked into the jail the same way the user is; otherwise it would be possible for the user to break out of the jail with cd documents.  (No, root-created symlinks can't be treated specially, for the same reason that cd -P symlink-to-dir; cd .. leaves you in the wrong place; the appearance of it working as you'd expect is an illusion created by the shell.)  Use a bind mount instead (mount --bind /var/ftp/files/documents /var/ftp/users/test/documents).


Installing Huawei dongle in Ubuntu 12.04

If you are using the cd, it doesn't need it. You can just plug it in and go to your network connections and enable it.


Cannot resize Ubuntu partition with GParted (not extended partition)

Thanks go to crisp659 who commented with the solution.

Ubuntu partitions must be unmounted to be worked on. Usually done with a live USB. Can also do from another Linux OS. Do not know how Fedora and Elementary works. If Ubuntu is unmounted, edit info in your question.

– crip659 2 days ago

Might also need to move partitions around before resizing, to make room.

– crip659 2 days ago
I unmounted Ubuntu's partition, and after that I was able to resize/move it.


Bluetooth Support for Yoga 11s in ubuntu 14.04

I had the same problem with a Lenovo Ideapad 710.

A lsusb return

Bus 002 Device 002: ID 8087:8000 Intel Corp.
Bus 002 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 001 Device 002: ID 8087:8008 Intel Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 004 Device 001: ID 1d6b:0003 Linux Foundation 3.0 root hub
Bus 003 Device 007: ID 0cf3:3004 Atheros Communications, Inc.
Bus 003 Device 006: ID 03f0:1024 Hewlett-Packard Smart Card Keyboard
Bus 003 Device 005: ID 5986:0295 Acer, Inc
Bus 003 Device 004: ID 058f:6366 Alcor Micro Corp. Multi Flash Reader
Bus 003 Device 003: ID 0461:4d51 Primax Electronics, Ltd 0Y357C PMX-MMOCZUL (B) [Dell Laser Mouse]
Bus 003 Device 002: ID 046d:c52b Logitech, Inc. Unifying Receiver
Bus 003 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub

Goggling the USB ID's you can find which one is the Bluetooth device in my case 0cf3:3004 Atheros is in fact the Atheros AR3012 Bluetooth device.

Then if you perform a dmesg output I could find two lines saying

[   13.946058] Bluetooth: Patch file not found ar3k/AthrBT_0x01020200.dfu
[   13.946058] Bluetooth: Loading patch file failed

Goggling again AthrBT_0x01020200.dfu the problem is solved installing the firmwares package linux-firmware

sudo apt-get install linux-firmware

which install the firmware file /lib/firmware/ar3k/AthrBT_0x01020200.dfu.

That solve the problem.


In linux, the drivers for the integrated graphics is included in the kernel. However, it seems linux drivers tend to cause more issues than in Windows.

I see two possible solutions:

In Google Chrome(I'm assuming) settings, disable hardware acceleration.
try downgrading/upgrading the linux kernel


OverGrive not work after restart computer

From the installation instructions online :

NOTE : It is important to allow overGrive to finish the first sync completely. If the first sync does not complete it will open the overGrive setup screen again on restart. You can simply select Start Sync again to complete the synchronization process.


While this may not correct the issue with Firefox, it may help you better deal with it.  Tell me, when Firefox is minimized as you have described, what does Alt+Tab buy you?  Are you able to select Firefox and begin working with it again?

Please let me know if I have missed the gist of your question, as I am having a little difficulty understanding exactly what you are asking.


I did a presentation on the differences between the Red Hat Way and the Debian Way at Ohio LinuxFest last year.  It includes things like package management and location of configuration files.  Slides are here:  http://www.slideshare.net/macoafi/sysadmins-rosetta-stone


Will Deja Dup backup from multiple accounts?

Yes. I have three users including the admin. All gets backed up in an internal hard drive in separate folders.

Each user has to setup Deja Dup from their own account. Backup will only happen if and when the user is logged on.

I don't have any experience using Deja Dup with an external hard drive. You may have to make sure your other user has the read/write access to the backup folder of the external hard drive.

Hope this helps


Restarting after installation takes me to a black screen with cursor blinking or installation prompt

Problem solved:

I had to manually format the partitions because the default installation wasn't putting it in the right spots that would connect during the booting phase. Since I planned on solely using Linux, I removed all other partitions and followed the instructions from this link: https://forums.linuxmint.com/viewtopic.php?t=122276.

Hope this helps someone!


How to make journald increase logs storage capacity?

I think you have to increase SystemMaxUse=

From https://www.freedesktop.org/software/systemd/man/journald.conf.html

SystemMaxUse=, SystemKeepFree=, SystemMaxFileSize=, SystemMaxFiles=,
 RuntimeMaxUse=, RuntimeKeepFree=, RuntimeMaxFileSize=, RuntimeMaxFiles=

The first pair defaults to 10% and the second to 15% of the size of the respective file system, but each value is capped to 4G.


Remove those panel first.

sudo apt-get --purge autoremove gnome-panel gnome-panel-data gnome-session-flashback

Then, Try resetting gnome settings using this command

dconf reset -f /org/gnome/

This should reset the session and settings.


I personally use the English (International AltGr dead keys) layout on an english keyboard. I type mostly stuff in english but also need accents and special characters for spanish, and occasionally some french. I've found this layout the best, really versatile for most accented character needs and saves me from constantly switching layouts which I consider very distracting :

All keys work as marked on the keyboard
When you need a special character, press AltGr (right Alt key) in combination with a letter or symbol. For instance, AltGr+vowel =
accented vowel (áéíóú). AltGr+n = ñ.
You can "compose" by pressing, for instance, AltGr+6 and a vowel (circumflex, like ê), or AltGr+` and a vowel (grave accent, è), or AltGr+" and a vowel for diaeresis (ü).
AltGr+! = ¡ and AltGr+? = ¿
Many more useful mappings, here's a full keyboard map:

You can get this keyboard map on your computer, go to Keyboard Layouts, select a layout, and click on the little keyboard icon (last icon on the right, below the layouts list). This will help you get acquainted with the layout.

Getting used to pressing two keys for accented letters is a bit strange, but it's doable (took me about a week to get up to speed).


Can Ubuntu ignore the Wireless Hardware Switch?

Check your BIOS. HP has some HP-only features in the BIOS.  In the Built-In Device Configuration menu there should be an option LAN/WLAN-Switching.  You should be able to disable it there.  (it has been a while since I had a HP so if this is not correct please comment ;) )


I try to fill or complement what @SeanBright leaved out:

Feature                              rpm                                   deb
----------------------------------------------------------------------------------
View all installed packages          rpm -qa                               dpkg -l, dpkg-query -Wf '${Package}\n'
View package info, installed package rpm -qi packagename (1)               apt-cache show packagename
View pre/post install shell scripts  rpm -q --scripts packagename          cat /var/lib/dpkg/info/packagename.{pre,post}{inst,rm}
View changelog for a package file    rpm -qp --changelog ./packagename.rpm dpkg-deb --fsys-tarfile packagename.deb | tar -O -xvf - ./usr/share/doc/packagename/changelog.gz | gunzip
Uninstall a package                  rpm -e packagename                    apt-get remove/purge packagename
Upgrade a package from a file        rpm -Uvh ./packagename.rpm            dpkg -i packagename.deb
Find which package owns a file       rpm -qif /some/file.foo               dpkg -S /dome/file.foo
List dependencies of a package       rpm -q --requires packagename         apt-cache depends package
List dependencies of a package file  rpm -qp --requires ./packagename.rpm  (shown in package's info)


Nvidia Drivers and Kernel Update Problems (nomodeset)

Nouveau is a attempt to replace the NVIDIA obfuscated driver and put it in the kernel. No modeset tells the kernel, not to attempt to set the screenmode. Nouveau would have to do that. However, my experience with an NVIDIA 690 is that nouveau starts to panic at my card and the boot system hangs. A sign to me, that nouveau is still not mature, because the 690 has been around for a while now.

About the driver: nouveau is a kernel component that you can not deactivate through ' additional drivers / restricted drivers' because these drivers are the ones you use for X windows.

what I did, is I added NOMODESET in the list of kernel parameters in grub, permanently.
When the system boots the kernel checks this setting and reacts accordingly.

For Ubuntu 12.04 the setting is stored in /etc/default/grub . You add it to the line titled GRUB_CMDLINE_LINUX_DEFAULT. If the line says:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

you would change it to:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash nomodeset"

After adding NOMODESET to this line you should run sudo update-grub to allow grub2 to see it the next time you boot.


One solution is to use pip instead of easy_install to install pybloomfiltermmap:

sudo pip install pybloomfiltermmap

But the real solution is to use the package avaliable in the Ubuntu repositories:

sudo apt-get install python-pybloomfiltermmap

Related bug on launchpad: https://bugs.launchpad.net/ubuntu/+source/w3af/+bug/1096580


Chrome Popup Malware "openadserving.com"?

You haven't provided sufficient information to identify the problem accurately, but the following suggestions may help to identify or even hopefully solve it:

You can open your hosts file (enter this command in terminal: gksu gedit /etc/hosts) and enter this line at the bottom: 127.0.0.1    www.openadserving.com As this will prevent all connection between this site and your computer after restart, this might solve your problem or if it doesn't, then;
You can try a program like Net Activity Viewer to see a list of sites your browser is being connected, and add all undesirable addresses there as in the step 1.
You can try using a utility like hostsblock to prevent connection to such sites in general. (This utility can be downloaded and manually installed from ArchLinux repositories with just one minor modification, replacing pathname /etc/rc.d with /etc/init.d in these files: hostsblock.sh, hostsblock-urlcheck.sh and rc.conf)


Ubuntu 18.04.2 LTS freezes randomly - the cursor will not move either. Any solution to prevent this from happening?

I had similar problems and it turned out to be due to a problem with the "nouveau" graphics driver that was used by default. In my case it was solved by installing another graphics driver, like this:

sudo apt install nvidia-driver-390

Then that newly installed driver was used instead of the nouveau driver, and then everything worked fine.

In case it freezes already before you can get a terminal and enter that apt command, you can try booting to Linux in runlevel 3 (no graphics) first; that worked for me.


If you don't know your Ubuntu boot partition, check them one by one:

ls (hd0,msdos5)/
ls (hd0,msdos1)/

When you hit the right one, you'll get a line mentioning "lost+found" and so on.

Assuming (hd0,msdos5) is the right partition:

set root=(hd0,msdos5)
set prefix=(hd0,msdos5)/boot/grub
insmod normal
normal

Now you'll be able to boot into Ubuntu. Once you do, reinstall GRUB:

sudo update-grub
sudo grub-install /dev/sda


I have exactly the same problem. I have searched the internet for answers but all answers are pretty much the same and not solving my issue. I can read from HFS drives and have disabled the Journaling via Mac OS, but still can't write.
Forcing the rw on mount command does nothing.


Problem in downloading videos using youtube-dl from unsupported sites

You can't, there's no support for that site yet.

The best thing you could do, probably ask youtube-dl developer to add support to your desired site, login to GitHub and propose new issue https://github.com/ytdl-org/youtube-dl/issues/new/choose, label them site-support-request

There's plenty people already done the same as you are → https://github.com/ytdl-org/youtube-dl/labels/site-support-request


This is an old issue that dates back to Ubuntu 11.10 at least. It happens regularly, although less frequently now, but you'll always have to repair the headers manually. The quickest way of doing it is by running:

sudo apt-get remove virtualbox-dkms
sudo apt-get install virtualbox-dkms

You can also create an alias for these commands as shown here.


Do I need to install a firewall, or is there already one active pre-installed?

No, there's no firewall pre-installed. It's only needed when you are opening up some ports to the outside internet, such as for hosting a server (especially for hosting webservers), using remote desktop, or things like that. Stuff like skype uses ports but it won't really create the need for a firewall.

If you need one: Ufw is a simple good firewall. You can install it with this command:

sudo apt-get install ufw

To start it, run this one (make sure you ran the above command as well):

sudo ufw enable

If you're not such a geek, but still want to have a firewall running, use this one instead,

sudo apt-get install gufw

This will install ufw, and the graphical user interface (GUI) that you can control ufw with. You do not need to install ufw first if you install this.

After that, you can start configuring ufw by running this command in a terminal:

gufw

To start right away, just click the enable switch. You may want to add some firewall rules for programs that you use. Refer to the FAQ of any program that you think is waiting for incoming connections, at any time, even briefly. These are especially instant message (IM) programs, such as Skype, Steam, remote desktop servers, or things like that.


Is there a difference between SWAP and Cache memory?

Yes. They are a complete different thing, even the opposite in a lot of ways. I will try to explain both simply and short. Note that this answer are just a simplification and the real thing is quite more complex. Click on the wikipedia links for a better explanation.

Disk Cache memory: This are chunks of the physical memory, the RAM, used to store files. That way when a program needs to read the file, it's fetched from memory instead of the hard disk. This is done because memory is way faster.
Swap: This is a place on the hard disk (usually a dedicated partition) that is used to store programs or data that can't fit in memory, like when a program grows more than the available memory. SWAP is way slower than RAM, so when you hit swap the computer gets slower, but at least the program can work. In linux swap is also used to hibernate, or to move low used program out of memory to allow more space to the disk cache.


I think you can fix it with Mount-Manager.
But first backup your fstab (sudo cp /etc/fstab /etc/fstab.bak).

You have not lost 3GB, this is how each software interpret the space of the disk. Look at your others partitions, all are "smaller" at GParted.


Installing software center in Lubuntu running via Virtual Box?

To install the Ubuntu Software Center in Lubuntu open Synaptic Package Manager from System Tools and install the software-center package.

This will install the Software Center to System Tools menu.


Stop building rsvg-view-3. It has been removed upstream and will not
be included in librsvg 2.45.x. The upstream developer of librsvg
suggests eog as a better interactive GUI SVG viewer; display(1) from
ImageMagick is another possibility.*
https://ubuntu.pkgs.org/20.04/ubuntu-universe-arm64/librsvg2-bin_2.48.2-1_arm64.deb.html


grub2 loopback booting ubuntu server iso

the solution to the problem is an easy one ,
today i wanted to install ubuntu-12.04 server on my atom server , which obviously doesn't have a cdrom , and i succeeded this way .
with this grub configuration :

menuentry "ubuntu-12.04-server-amd64.iso" {

set isofile="/path/to/ubuntu-12.04-server-amd64.iso"
loopback loop (hdX,Y)$isofile
linux (loop)/install/vmlinuz file=$isofile/preseed/ubuntu-server.seed iso-scan/filename=$isofile quiet noeject noprompt splash --
initrd (loop)/install/initrd.gz
}

, the computer will reach the setup screen , when you are there , press Alt+F2 , and do the following:

mkdir /media/bla
mount /dev/sdXY /media/bla
mkdir /cdrom
mount -o loop,ro -t iso9660 /media/bla/path/to/ubuntu-12.04-server-amd64.iso /cdrom

then press Alt+F1 again , and continue the normal install process , note that , you must not format /dev/sdXY .
the installation will work flawlessly , till you reach the configuring apt step , it returned no error , and just didn't work , i simply skipped everything up until installing boot loader on the disk .
reboot the system ,
and voila !!!
everything works , the only thing that i've noticed is that , the /etc/apt/sources.conf is empty , you must populate it the way you need it .

hope it helps .


Problem connecting to Pi through SSH with Ethernet cable in Ubuntu

This should work if you have both your RPi and your Ubuntu machine on the same subnet. Set the IP address and subnet mask on your Ubuntu machine manually such that it's on the same subnet as your RPI, but with a different IP. Do this:

pi@raspberrypi3b:~ $ ifconfig eth0
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST>  mtu 1500
        inet 192.168.0.14  netmask 255.255.255.0  broadcast 192.168.0.255
        inet6 fe80::53b3:8c82:c0d6:57d5  prefixlen 64  scopeid 0x20<link>
        ether b8:27:eb:cd:2f:ff  txqueuelen 1000  (Ethernet)
        RX packets 143870  bytes 30387506 (28.9 MiB)
        RX errors 0  dropped 65635  overruns 0  frame 0
        TX packets 32375  bytes 4042276 (3.8 MiB)
        TX errors 0  dropped 0 overruns 0  carrier 0  collisions 0

In this case you would manually set the IP address on your Ubuntu machine to 192.168.0.100 (for example), and set the subnet mask to 255.255.255.0. Or, to put this in CIDR notation: 192.168.1.100/24. And the Ubuntu docs already explain how to set your IP address manually, so I'll not repeat that here. (And here's the "GUI Approach" to manual network configuration)

I've not done this in a while, but I think it will work. Let us know how you get on.


Ubuntu 14.04 and Intel Graphics (Q33/GMA)

Intel still has no driver support for 14.04, use 13.10 instead and dowmload the intel drivers for Linux 1.0.4


Mounting network share with CIFS stopped working on 17.10

I had the same symptoms and solved it by specifying using SMB1, for you that would be modifying it to be:

//nas/shared/ /media/nas cifs username=(username),password=(pass),uid=1000,gid=1000,iocharset=utf8,sec=ntlm,vers=1.0  0  0

If you want to be sure check your logs for cifs related messages.


Why the secure boot blocked the wifi drivers

The problem with open source drivers is that not all of them are "signed" drivers.  "Signed" drivers are drivers which have been signed with a digital identity code signing certificate to indicate the legitimacy of the developers.

Many open source drivers don't have this digital signature (it's not the easiest thing in the world to get a code signing certificate, and it's not really that cheap - $170/year and it requires you to provide detailed documentation that you as a business entity are real and can be considered a business or organization under the law), and as a result SecureBoot can't properly permit them, because they're not 'signed' and 'secured' drivers.

In those cases, you have to disable SecureBoot.  In Windows, most drivers are signed, except for open source ones which you install separately, which aren't always signed.

Regardless of the OS, SecureBoot requires signed drivers.  It's just an extra layer of security, so unless you're installing suspicious drivers and such all the time, it's up to you whether you keep SecureBoot on or off, and if hardware you're using isn't signed and you need the hardware because it's critical, then you've got no choice but to disable SecureBoot, or sign the drivers yourself (which for various reasons might not be doable).

Having to disable SecureBoot for Linux installs and drivers is also not uncommon, either, as this is and was a common occurrence ever since SecureBoot was initially introduced.


What app to download Torrents or how to start mTorrent

Try transmission. It's installed in 12.10


It's just a keyboard configuration issue. Your computer assumes your keyboard is American but it's actually British (or something else with that crossover). It's fairly simlpe to fix from a terminal:

sudo dpkg-reconfigure keyboard-configuration

As stolen from this question.


I am not sure if this is possible fix for all the versions, but I was facing same issue. I had used deb file from skype website. That always kept crashing. So I uninstalled it and installed skype from Canonical Partner repo. Its been stable ever since.


Kubuntu 18.04 LTS (Kernel panic after unfinished update):- Missing Sectors

From the comments...

The user was trying to do a Software Update, and it failed.

We ran a number of tests, including fsck. No errors found there.

The original system that uses the [4.15.0-20] kernel will still boot. Software Updater won't run.

The failed system that uses the [4.15.0-36] kernel will not boot. It's missing initrd.img-4.15.0-36.

We did various tests, and Ubuntu may need to be reinstalled.


Posting this here is likely to get a thousand beardies running at you with "BASH IS BETTER THAN POWARSHELL!" If I could grow a beard, I would probably be one of them.

But if you have an assignment that involves Windows Powershell, there's little choice. There are some shells (and even modifiers existing shells like zsh)  that aim to pull in some of the PowerShell features but even if they're syntactially identical, the underlying data you're using just won't be the same.

In short: if you need to use Windows, use Windows. And you do.

That said, that doesn't mean you have to reinstall Windows properly. It could temporarily languish in a virtual machine (see VirtualBox). Easy to install, easier to remove, can't touch your existing setup. It'll be a bit slower than a native install but given you're just playing around with a command line, that doesn't seem like an issue at all.


Ubuntu 20.04 on Dell XPS 15 desktop lags

Problem fixed! I have extension indicator-multiload, to show CPU, RAM and disk usage in toolbar. After disable this extension freezes gone. So if any one have same issue chech system load indicators extensions, base on my fast google this problemcan can also be with system-monitor extension, but not sure.


Integration of manually locally installed libs into system?

No you can't.

The Debian/Ubuntu package management (APT) has no control over your user-specific installed libraries. This is intentional. Intentional why? This would break security in a certain aspect - local users would have the ability to 'own' the system libraries.

In case you need specific versions of Python libraries I would recommend using pip to manage them in your local (home) directories. Also consider building your own .deb packages in case you want to distribute them in case other stuff doesn't break on this being installed system-wide.


Looks like a permissions problem unless the drive is very old which have been know to cause intermittent permissions problems. Check out this document from Ubuntu to learn about this kind of errors.


MariaDB 10.1 server won't start after update

Here's how I solved my issue, I didn't have a backup of the server so I sort of "hard reset" MariaDB:

First, I backed up my /var/lib/mysql folder: I'm assuming I have a /home/ubuntu folder and copying the folder there.

cp -r /var/lib/mysql /home/ubuntu/

Secondly, I backed up my /etc/mysql folder: I'm assuming I have a /home/ubuntu folder and copy the folder there.

mkdir /home/ubuntu/etc_mysql
cp -r /etc/mysql /home/ubuntu/etc_mysql

Then I removed /var/lib/mysql and /etc/mysql folders

rm -rf /etc/mysql
rm -rf /var/lib/mysql

After that, I purged MariaDB:

apt-get purge mariadb-server mariadb-* mysql-*
apt-get autoremove

After purging, I re-installed mariadb-server and re-configured it:

apt-get install mariadb-server
mysql_secure_installation

Copy whatever config you need from /home/ubuntu/etc_mysql folder.

After that, I created my database and user from mysql cli (or however you want)

Lastly, I copied my /home/ubuntu/mysql/**databaseName** folder to /var/lib/mysql/**databaseName**

cp -r /home/ubuntu/mysql/databaseName /var/lib/mysql/

And then, I could access my data without loss, just as I'd left it.


Is the user connecting via ssh ? If so, there is a ChrootDirectory option to jail a user to a specified directory, meaning he can not navigate higher up the directory tree. Take a look here for a working example

https://www.debian-administration.org/article/590/OpenSSH_SFTP_chroot_with_ChrootDirectory


It turns out that my raid0 configuration was really a "fakeraid" configuration. It also turns out that there was a bug in grub-probe related to fakeraid. Once I ran sudo update grub-pc followed by grub-install /dev/mapper/isw_fbifcgeic_RaidVolume0 I could successfully boot my computer once more without manual intervention.


Better perform a sudo apt-get update and sudo apt-get upgrade


The only reliable solution I've been able to find is:
sudo apt install earlyoom

The "early out of memory"-killer will terminate any process that pushes your computer into disk thrashing and the resulting freezing. I think most Chrome developers have much more RAM than most users, so they hardly ever run into these sort of issues.
There is another more manual way of dealing with it: you can press AltSysRQF to manually invoke the OOM killer. But for that to work you need to enable it:
$ sudo sed -i s@#kernel.sysrq@kernel.sysrq@g /etc/sysctl.conf
$ sudo sysctl -w kernel.sysrq=1

SysRQ is labelled Print Screen  or PrtScron many keyboards, and on some others you have to press Fn to access it, making the full combination of keysAltFnPrtScrF. On some keyboards only the right hand Alt works.
These methods essentially force the browser or offending application to crash, and free up its memory. There used to be browser addons that suspend background processes, but at the time of writing they cause more problems than they solve, so I won't link them - and nowadays most Chrome and Firefox just keep crashed tabs suspended in the background until you click on them, so the impact of a crash is minimal - but do check your add-ons as besides memory hungry web-apps, they are the most likely culprits.


There is no Network Manager in the panel for the second user

This is a well known upstream bug that appears to be unfixable. It has been open for over two years. You can see the bug report here.

In the event that you are logged in second and you therefore do not have the nm-applet in your panel, you can run the following command to kill the currently running instance and then restart network manager for your login

sudo killall -9 nm-applet && nm-applet &


Is there any way to get ubuntu 13.10 to stop asking for my password

If you use auto-login and your keyring password is different than your login password you can remove the keyring password in „Passwords and Encryption Keys“:

There should be entries listing different passwords. Right click there and change the password. If not, check the settings:

For using sudo without being prompted for a password, you might use an USB Flash Drive USB Flash Drive for authentication:

 apt-get install libpam-usb pamusb-tools
 pamusb-conf --add-device YourUSB
 pamusb-conf --add-user Username


This sounds like buggy firmware. Check for an update on Acer's site. (It will probably be called a "BIOS update" or something similar, although if the computer was sold any times since late 2011, it's more likely to be an EFI/UEFI than a BIOS.)

If there's no firmware update, or if applying it doesn't help, then you should complain -- loudly -- to Acer, since this is a serious bug. Beyond complaining, there are better workarounds than what you're using:

fbx64.efi -- Recently, Ubuntu has begun shipping this EFI program file and installing it in /boot/efi/EFI/ubuntu (from Ubuntu). I have yet to study this file in detail, but it's intended to work around the sort of problem you're describing. To work automatically, you'd probably want to copy it to /boot/efi/EFI/bootx64.efi (from Ubuntu), but it may require explicit configuration beyond that, and I haven't yet looked into that detail. Also, this might not really do anything by itself if your computer boots straight to Windows. Thus, you might want to focus on the next solution....
Fix the boot entries -- One or both of two NVRAM-based EFI settings are being changed: The BootOrder variable holds the boot order, and Boot#### entries (where #### is a hexadecimal value) hold pointers to specific boot loaders. If the BootOrder alone is being changed, you can fix it with various tools, like efibootmgr in Ubuntu or bcdedit in Windows. Since you're booting straight to Windows after such an incident, the easiest fix is likely to be to use the third-party EasyUEFI tool, which enables you to adjust the BootOrder variable in a simple GUI list. Even if the Boot#### entry for Ubuntu is being deleted, you can use EasyUEFI or bcdedit to create a new entry that points to EFI\ubuntu\shimx64.efi. Typing bcdedit /set {bootmgr} "\EFI\ubuntu\shimx64.efi" in an Administrator Command Prompt window should fix the problem with bcdedit; or you can do the equivalent in EasyUEFI.

This is just one example of what I call a boot coup. See this page of mine for more on this subject. (That page is part of my rEFInd documentation, but the principles apply to other boot loaders.)


Compiz profile is screwed up when switching from Unity to GNOME Classic

There are 2 different profiles in a fresh install - the unity & the default profile

The default profile by default doesn't have the Unity plugin enabled & uses the 'static application switcher', probably a few other diff.'s

At some point you may have switched to using the 'default' profile while logging into Ubuntu (unity-3d) & enabled unity, ect.

You may be able to set all back with a gconftool command but try this 1st. -

Login to Ubuntu  (unity-3d) & then open this file

gedit ~/.config/compiz-1/compizconfig/config

If it has this section in it then remove [general_ubuntu]  & all below it, save. (or just remove all from the file & save as an empty file

[general_ubuntu]
profile =

Then open a terminal  & run ccsm, it should show on line 5

Profile     : unity

If so then your Ubuntu login is  on the unity profile where it belongs

Then log out & in to Classic - start compiz if need be, then run ccsm from there. Line 5 should show

Profile     : default

If so then any ccsm changes made in either Classic or Ubuntu logins will not affect the other login

Edit:

The moment you click on "Preferences" in ccsm while in the Ubuntu session you will be switched from the 'unity' profile to the 'default' profile.

Sometimes this causes a hang, other times if you wait the desktop (control) will return, usually sans unity.

Here is a bug I have on this unfortunate occurence

https://bugs.launchpad.net/ubuntu/+source/compizconfig-settings-manager/+bug/880679


WiFi on Acer Aspire with Ubuntu 14.04 randomly disconnects

I suggest you try a driver parameter; from the terminal:

echo "options rtl8723be fwlps=N ips=N" | sudo tee /etc/modprobe.d/rtl8723be.conf

Reboot and tell us if stability is improved.

Next, write a configuration file:

gksudo gedit /etc/pm/config.d/config

Add a single line:

SUSPEND_MODULES="rtl8723be"

Proofread carefully, save and close gedit. Reboot.

We wonder if there is some other module besides rtl8723be that drops and doesn't reload as expected. After a reboot, when wireless is working, run:

lsmod  >  wifi.txt

Suspend, then resume and when wireless is not working, run:

echo ----------------  >>  wifi.txt
lsmod  >>  wifi.txt
rfkill list all  >>  wifi.txt

Find the file wifi.txt in your user directory and post it here: http://paste.ubuntu.com Give us the link in your reply.


How to combine multiple commands in terminal?

Yes, separate with a semi-colon like so:

dir; ls -l

Most lanugauges/shells use the semi-colon to signify the end of a command and to start new while evaluating from left to right.

Or as @RobieBasak recommends, use && instead of ; to guard against coding accidents.

dir && ls -l


How do I use a shell command as a launcher shortcut?

In its most basic form:

create a .desktop file (paste the text below in an empty file):

[Desktop Entry]
Name=Start Teamspeak
Exec=/bin/bash /home/flux/Downloads/TeamSpeak3-Client-linux_amd64/ts3client_runscript.sh
Icon=/path/to/your/icon
Type=Application

save the file as team.desktop in ~/.local/share/applications and drag it from there on to the launcher.

Explanation

Running scripts from a .desktop file

If you run a script in the Exec= line from a launcher like this, it works like in the terminal:

If the script is not executable:

language /path/to/script.language_extension

If the script is executable, just:

/path/to/script.sh

If the script is executable, the language extension is not strictly needed. However, if you use it on the file, also use it in the command.

Running more complicated shell commands from a .desktop file

Exec=/bin/bash -c "your_complicated_command_here"
(command inside quotes)


You probably don't need the answer anymore, but there might be others interested in this.

1. Navigation:

uNav

https://uappexplorer.com/app/navigator.costales

On and offline maps provided Open Street Maps and Mapzen. Features turn-by-turn voice navigation.

2. WhatsApp-like:

Telegram

https://uappexplorer.com/app/com.ubuntu.telegram

Telegram works like a charm and is very similar to WhatsApp, this one is backed by the Ubuntu Touch core dev team.

LoquiIM

https://open.uappexplorer.com/app/com.ubuntu.loqui.im.loqui

Third party WhatsApp client, works, but some features are yet to be implemented.

Also, there are several Webapps for WhatsApp, but since WhatsApp Web sucks a whole bunch, it's not really usable. But hey, maybe we will see an official client in the future!

3. User Guide

I don't think so. Just do trial and error, read some blogs, watch some videos and google your way through it. Or ask here. :)

4. Email

Since the question was about essentials, i will add the Dekko email client. The best way to write email on UT for now.

https://uappexplorer.com/app/dekko.dekkoproject

5. What else?

Have a look around the store:

https://uappexplorer.com/

And also the open store:

https://open.uappexplorer.com/

Also, some desktop applications can be installed, but that's to much to explain here...

Have fun with Ubuntu Touch!


"Security updates for current Hardware Enablement Stack (HWE) ended on 2016-08-04”

The solution was buried in https://wiki.ubuntu.com/1404_HWE_EOL : I needed to upgrade to xserver-xorg-lts-xenial and dump the old kernel (4.2.0) in favour of the newer one (4.4.0) installed by that suite of packages.


I've found this series of tutorials to be very useful:

http://arstechnica.com/information-technology/2014/02/how-to-run-your-own-e-mail-server-with-your-own-domain-part-1/2/

http://arstechnica.com/information-technology/2014/03/taking-e-mail-back-part-2-arming-your-server-with-postfix-dovecot/

http://arstechnica.com/business/2014/03/taking-e-mail-back-part-3-fortifying-your-box-against-spammers/


How to secure Ubuntu for a non-technical user? (your mom)

The number one thing you can do to keep that computer secure is to ensure that the packages are updated regularly.  I would enable fully automatic updates (https://help.ubuntu.com/community/AutomaticSecurityUpdates), as long as the potential for a burst of network use while connected to dodgy hotel WiFi isn't a severe problem.

After that, I think the only big problem is VNC.  If VNC server is running constantly, it is probably the biggest potential security issue on the system (SSH is similar in scope but is considered to be more secure by default).  If you need VNC installed and need it to be running all of the time, then there's probably nothing you can do about it -- it's either running or it's not, and there's not much you can do to secure a process that has control over input/output like VNC does.  But if you don't need it to be on all the time, then just disable it.  You can start it up manually via SSH if you need to.

As long as your packages are up to date, I wouldn't worry about web browsing, USB sticks, malware or SSH vulnerabilities.  Linux desktops/notebooks are not a common target for them and Ubuntu is fairly well hardened by design.  Even if you don't do anything special to secure against those vulnerabilities, an Ubuntu system will be less likely to be compromised than a Windows machine running even fairly good security software.

Skype is not necessarily secure, but it doesn't run with elevated privileges and there's not very much you can do to secure it given the state of the Skype linux version.  Just be aware that Skype for Linux is not very stable or featureful and hasn't been worked on for a long time.  That having been said, I use it for business purposes all the time and after I got used to its quirks it was adequate.


I removed /usr/lib/xorg by mistake, will copying it from the live cd be enough to repair?

The content of the directory /usr/lib/xorg is a little harder to replace than the single binary file /usr/bin/Xorg. You can still do it by just reinstalling packages, but it's made up of many packages, some of which won't apply to you.

$ find /usr/lib/xorg -exec dpkg -S {} + | cut -d: -f1 | sed -e 's/, /\n/g' | sort -u
xserver-common
xserver-xorg-core
xserver-xorg-input-evdev
xserver-xorg-input-synaptics
xserver-xorg-input-wacom
xserver-xorg-video-ati
xserver-xorg-video-cirrus
xserver-xorg-video-fbdev
xserver-xorg-video-intel
xserver-xorg-video-mach64
xserver-xorg-video-mga
xserver-xorg-video-neomagic
xserver-xorg-video-nouveau
xserver-xorg-video-openchrome
xserver-xorg-video-qxl
xserver-xorg-video-r128
xserver-xorg-video-radeon
xserver-xorg-video-s3
xserver-xorg-video-savage
xserver-xorg-video-siliconmotion
xserver-xorg-video-sisusb
xserver-xorg-video-tdfx
xserver-xorg-video-trident
xserver-xorg-video-vesa
xserver-xorg-video-vmware

While this is from a fairly stock machine, I'd check you have each of those installed already with the following:

apt-cache policy xserver-common xserver-common xserver-xorg-core \
xserver-xorg-input-evdev xserver-xorg-input-synaptics xserver-xorg-input-wacom \
xserver-xorg-video-ati xserver-xorg-video-cirrus xserver-xorg-video-fbdev \
xserver-xorg-video-intel xserver-xorg-video-mach64 xserver-xorg-video-mga \
xserver-xorg-video-neomagic xserver-xorg-video-nouveau \
xserver-xorg-video-openchrome xserver-xorg-video-qxl xserver-xorg-video-r128 \
xserver-xorg-video-radeon xserver-xorg-video-s3 xserver-xorg-video-savage \
xserver-xorg-video-siliconmotion xserver-xorg-video-sisusb xserver-xorg-video-tdfx \
xserver-xorg-video-trident xserver-xorg-video-vesa xserver-xorg-video-vmware

And assuming you want all of those, reinstall:

sudo apt-get --reinstall install xserver-common xserver-xorg-core \
xserver-xorg-input-evdev xserver-xorg-input-synaptics xserver-xorg-input-wacom \
xserver-xorg-video-ati xserver-xorg-video-cirrus xserver-xorg-video-fbdev \
xserver-xorg-video-intel xserver-xorg-video-mach64 xserver-xorg-video-mga \
xserver-xorg-video-neomagic xserver-xorg-video-nouveau \
xserver-xorg-video-openchrome xserver-xorg-video-qxl xserver-xorg-video-r128 \
xserver-xorg-video-radeon xserver-xorg-video-s3 xserver-xorg-video-savage \
xserver-xorg-video-siliconmotion xserver-xorg-video-sisusb xserver-xorg-video-tdfx \
xserver-xorg-video-trident xserver-xorg-video-vesa xserver-xorg-video-vmware

If you did just mean /usr/bin/Xorg, you just need to:

sudo apt-get --reinstall install xserver-xorg-core