Kernel panics with "Cannot open root device" error, where do I append the "root=" option?

You haven't provided much information with logs and such to proceed with but I am guessing most probably this error you're facing is because the kernel is confused by a IDE/SATA drive. Doing a quick Google search led me to link 1, link 2, link 3

Following is the excerpt from a link referred to by one of the links above:

  Most likely one of the most occurring issue (but once you solved it,
  you most likely are never going to see it again):

Unable to mount root fs on unknown-block(0,0)

  or

VFS: Cannot open root device "sda3" or unknown-block(8,3)
Please append a correct "root=" boot option; here are the available partitions:
  sda driver: sd
    sda1 sda2

  The digits 0,0 or 8,3 can be different in your case - it refers to
  the device that the kernel tries to access (and which fails).
  Generally speaking one can say that, if the first digit is 0, then the
  kernel is unable to identify the hardware. If it is another digit
  (like 8), it is unable to identify the file system (but is able to
  access the hardware).

  The problem here is that the kernel that you are booting cannot
  translate the root=/dev/... parameter you gave it (inside the boot
  loader configuration) into a real, accessible file system. Several
  reasons can result in such a failure:

  the kernel configuration is missing drivers for your HDD controller    (cases 1, 4, 5)
  the kernel configuration is missing drivers for the bus used by your    HDD controller
  the kernel configuration is missing drivers for the file system you    are using
  the device is misidentified in your root= parameter (cases 2, 3)

  Resolving the issue is easy if you know what the reason is. You most
  likely don't, so here's a quick check-up.

  Open the kernel configuration wizard (the make menuconfig part) so
  that you can update the kernel configuration accordingly.

  Check if you have built in (and not as a module) support for the bus    / protocol that your harddisk controller uses.
  Most likely this is PCI support, SATA support (which is beneath SCSI    device support), ...
  Check if you have built in (and not as a module) support for the HDD    controller you use.
     One of the most frequent cases: you selected support for your    harddisk controller protocol (IDE, SATA, SCSI, ...) but forgot to
  select the HDD controller driver itself (like Intel PIIX). Try
  running the following lscpi command, and paste its output on
  http://kmuto.jp/debian/hcl/. The site will show you which kernel
  drivers you need to select for your system. Within the menuconfig,
  you can type "/" to open the search function, and type in the driver
  name to find out where it resides.
     # lspci -n
  Check if you have built in (and not as a module) support for the file    system(s) you use.
  Say your root file system uses btrfs (which I definitely don't    recommend) but you didn't select it, or selected it to be built as a
  module, then you'll get the error you see. Make sure the file system
  support is built in the kernel.
  Check if the kernel parameter for root= is pointing to the correct    partition.

  This isn't as stupid as it sounds. When you are booted with one
  kernel, it might list your disks as being /dev/sda whereas your
  (configured) kernel is expecting it to be /dev/hda. This is not
  because kernels are inconsistent with each other, but because of the
  drivers used: older drivers use the hda syntax, newer sda.

  Try switching hda with sda (and hdb with sdb, and ...).

  Also, recent kernels give an overview of the partitions they found
  on the device told. If it does, it might help you identify if you
  misselected a partition (in the example given at the beginning of this
  section, only two partitions are found whereas the kernel was
  instructed to boot the third). If it doesn't, it is most likely
  because the kernel doesn't know the device to begin with (so it can't
  attempt to display partitions).
  Check if the kernel that is being boot by the boot loader is the    correct kernel.
     I have seen people who, after building a first kernel (which doesn't    boot), forget that they have to mount /boot before the
  overwrite the    kernel with a new one. As a result, they copy the
  kernel to the root    file system (/) whereas the boot loader still
  expects the kernel    image to be on the /boot partition.


Create Keyboard Macro to change modifier keys on Mac

Registering a command or a script to shortcut menu.

Swap Left Command (Super) key to Left Option (Alt) key.

Install setxkbmap by sudo apt install x11-xkb-utils
setxkbmap -option altwin:swap_lalt_lwin
This will swap ALT_L and Super_L

Register this command to your Shortcut items.

Now each time you press F12 Command key and Option key goes into another or goes back to normal.


It looks like you have an unterminated """ around line 119 that is still unterminated when you get to the end of the script. Carefully inspect lines around line 119, and make sure you have an even number of "s.

When I get this type of error, I do

grep -n '"' .bashrc


Can I install Ubuntu on a logical partition ? What will be the advantage or disadvantage of using a logical partition to install Ubuntu 12.04?

There is no advantage or disadvantage of installing Ubuntu on a primary or logical partition. The only "drawback" if you can call it that way is that if you select logical, the names of the /dev/sd will start at 5. But if you select primary they will start at 1.

For example:

Primary

/dev/sda1
/dev/sda2
...

Logical

/dev/sda5
/dev/sda6
...

Basically is nothing to worry about.

As far as I can see, you are good to go installing Ubuntu on that 55GB space you have left in your logical space. The one I mean is this:

So no need to worry about it. Just install it and enjoy.


Workspaces are copy of default workspace

I unchecked "workspaces only on primary display" in the gnome tweak tool and it fixed it for me. Maybe that will work for you too.


Apache - 403 Forbidden - changed dir for default in sites-available

OP posted

the problem was that i had SELinux installed, i think. I reinstalled linux, didn't "encrypt my home folder" and now it works. – André Alçada Padez Mar 5 '12 at 13:52


How can I define custom keyboard mappings to resize, move, and manage windows?

The best I've managed in Unity to bind the Compiz "grid" functions to Win+Left and Win+Right, and re-enable multiple workspaces. Unity lets you swap workspaces with Ctrl+Alt+[direction], and pull a window between workspaces with Ctrl+Alt+Shift+[direction]. The four default workspaces in unity are arranged in a "four corners" style, which I find makes them quite easy to keep track of. It works really, really well on a single monitor.

Unfortunately, Unity provides no good way to move a window between two monitors, and, as you pointed out, it's lacking in more granular window management options.

So, if you really want good window management, and you're alright with ditching Unity, I can't recommend xmonad strongly enough. It doesn't have Unity's UI polish, and customization can be tricky (you do all the scripting in Haskell), but once you're up and running, it's the absolute best keyboard-focused window manager I have ever used. Ever.

It has the resizing feature you mentioned built in. It also automatically resizes your windows as you open new ones, and puts one workspace on each monitor (rather than having a workspace "shared" between two monitors as in Unity or OSX).


Disable screenshots and leave only the icons while Alt-TAB on Ubuntu 19.04

The window switcher, which appears when you press Alt+Tab, can be set to display only the thumbnail of the window, only the app icon or both. The setting to change this is not exposed to the user, but can be changed using a command. Open a terminal and copy/paste following command to have the window switcher only show the application icon.

gsettings set org.gnome.shell.window-switcher app-icon-mode 'app-icon-only'

Change app-icon-only to thumbnail-only or both for the other options. Reset to default with the command

gsettings reset org.gnome.shell.window-switcher app-icon-mode

In Gnome Shell, the desktop environment used by Ubuntu, this and many other configuration settings can also be viewed and edited using a graphical tool, dconf-editor, which is not installed by default.


Can someone please ELI5 how to install the Unity desktop onto my Windows 8.1 install?

ELI5 version: You can't.

Long version: If you need Windows and need to get your Ubuntu fix, you might want to try installing Ubuntu in a virtual machine using VirtualBox, or dual-booting. There might be Windows themes/hacks to make it look like Ubuntu, but it won't be the actual Ubuntu desktop.


Probably your /etc/default/locale file incorrectly includes the line

LC_CTYPE="UTF-8"

If so, just remove that line. (There is no "UTF-8" locale name.)


In Recoll, how to view the list of files that have been indexed in a specific directory?

At least with recent Recoll versions, a query language request like:

dir:/path/to/dir

should return all files which lived in the subtree under dir.

If you switch to the table mode display for the results, you can use the Results->Save as CSV menu entry to produce an easily processed listing.

If the data is very precious, there are also ways to retrieve a raw likeness of the text contents from the index data.

Hope this helps. I'm not too sure I'll get a notice if this page is updated, so don't hesitate to reach me through the contact on the Recoll web site if you need more help.


Normally if this ssh-copy-id -i ~/.ssh/id_dsa/rsa.pub remote-host works properly it will

append the keys to the remote-host’s .ssh/authorized_key

After that you should be able to login to that particular remote-host without password.

NB: Can you provide some more detail like how you added the key? Also yo can verify that from the user you've generated the key also trying to ssh from the same user.

When no value is passed for the option -i and If ~/.ssh/identity.pub is not available, ssh-copy-id will display the following error message.

jsmith@local-host$ ssh-copy-id -i remote-host
/usr/bin/ssh-copy-id: ERROR: No identities found

You may have a look into the Using ssh-copy-id along with the ssh-add/ssh-agent section of This Link


You could get rid of that box by installing Ubuntu on your USB disk instead of just running a Live session.

All you basically have to do is boot Ubuntu from another USB disk or a Live DVD and use the USB drive as the target device during installation.


I'm assuming you're using 16.04?

  OPL 16.03 supports Ubuntu 14.04 LTS ("trusty"). It can only be upgraded from OPL 15.11. Ubuntu 16.04 LTS ("xenial") is NOT supported by OPL 16.03.


Busybox shell fallback occurs during the boot cycle when the root partition cannot be located, fails to mount, and/or the /sbin/init binary cannot be located on it.

Sometimes this is due to hardware failure, a loose connection, or other corruption. That causes the root partition to fail to mount.

Most commonly, this is due to a typo or mistake in grub. Take a look at the file /boot/grub/grub.cfg (in Grub2, which most users have migrated to. If you don't have the file, then you're using the older version of Grub).

There's a very good troubleshooting guide for Grub2 at https://help.ubuntu.com/community/Grub2

Basically, look for the like that says something like (there's one line like this for each choice in the grub menu):

linux /boot/vmlinuz-2.6.31-11-generic root=UUID=cb201140-52f8-4449-9a95-749b27b58ce8 ro quiet splash

Most problems are on this line. A typo or mistake on this like will kick you out to busybox.

1) Make sure the /boot/vmlinuz-$version line on that file is correct.

2) Use the 'blkid' command to check the disk UUIDs. Make sure the UUID matches the drive you want to boot from.


apt-get warning: No support for locale: en_US.utf8

Usually this error means that you could have been changing between different languages (locales) and something has caused this to error erroneously.

You could try regenerating your list of locales with

sudo dpkg-reconfigure locales

For me the result was:

Generating locales...
  en_AG.UTF-8... done
  en_AU.UTF-8... done
  en_BW.UTF-8... done
  en_CA.UTF-8... done
  en_DK.UTF-8... done
  en_GB.UTF-8... done
  en_HK.UTF-8... done
  en_IE.UTF-8... done
  en_IN.UTF-8... done
  en_NG.UTF-8... done
  en_NZ.UTF-8... done
  en_PH.UTF-8... done
  en_SG.UTF-8... done
  en_US.UTF-8... up-to-date
  en_ZA.UTF-8... done
  en_ZM.UTF-8... done
  en_ZW.UTF-8... done
Generation complete.

Then resetting your local locale with:

sudo update-locale LANG=en_US.UTF-8

i.e. use one of the Locale values in the output above


Is there a web based terminal/ssh client?

If the Library is using Firefox and has the ability to install add-ons, try FireSSH - its a javascript based SSH client.


When streaming / recording my desktop, how do I also record the audio?

The above command was okay.

At default it only records from the microphone entry slot. Since I had no microphone connected, no sound was recorded. But I want to record the "internal" sound anyway and not a microphone voiceover or something.

So I needed to install pavucontrol - like sudo apt-get install pavucontrol - to switch my recording source. Started it, gone to the Recording tab and changed audio capture to Monitor of Internal Audio Analog Stereo.

Seems that the setting is remembered. Every time I record a stream now, I record my internal sound.


Can't install Netbeans/JDK 7 on Ubuntu 14.10

Error E: Package 'package_name' has no installation candidate most probably means that the APT cannot find (i.e. download) the installation package.

To solve this, open Software and Updates and try changing Download from server (choose Main first). On my system it's Server for United States.

If it still does not work, then you can manually download the .deb package and install it.


Keep Screen On When Watching Online Videos

Your best bet is to disable the "Dim screen to save power" option and adjust the screen timeout under Brightnes & Lock in settings.


Why am I getting 'package cannot be authenticated' errors for google-chrome?

There seems to be one file missing from the Google download server -- see http://crbug.com/249188.

Until that's fixed it would be OK, but not entirely safe, to update without checking the signature.

If someone can intercept and interfere with your internet traffic they could send you a malicious replacement for Chrome, so I wouldn't do this over public wifi, for example.

update: Now it's fixed.


I can use BIOS password, but that is always crackable via some hardware means and this is not 100% safe.

All (well most and some might not be known yet ;) ) bios passwords can be circumvented by using a default password. No hardware required. Just physical access is enough.

  Is there any way I can setup my Ubuntu PCs authentication (login) username / password system via some cloud / online account.

No, and it would be rather pointless since it would create a false sense of security.

  Reason for this is, in case I lose access to my PC I can change my credentials online and therefore disabling access to PC and my data on my HDD.

You are wrong there. If someone has physcial access to your machine they will be able to access your data if it is not encrypted: all they need is a live cd or to enter grub rescue. Both will grant them root access. There is not even any form of password hacking required since these 2 are the general methods for resetting your admin password in case you forgot them.

  Any suggestions?

If you are that worried about your system please use (full disc or /home partition) encryption. This will make all data unreadable and only accesible when you log in with a password. Use a strong password and others will have a hard time getting to your data. Still not impossible (but it would take a long time to decrypt it).

And even full disc encryption is flawed: if someone really really wants your data nothing stops them from asking you to provide your password. 1 knife, 10 fingers. No contest.


I don't know why are you asking this question.But there are two options:

1.You only have to press the super key and type additional drivers. Then click on the icon of the additional drivers program
and scan for drivers. It will automatically show you the available drivers.
2.Go to the graphics engine website (nvidia.com/amd.com) and download the driver.


The Regex token inside character class for negation is ^, not !.

So you need:

ls | grep '^[^0-9]'

If you do ls | grep ^[!0-9], then within [], ! is treated literally and 0-9 is expanded in the usual manner.

Also for this kind of trivial tasks, use shell globbing, Regex is a bit too much for these, and also don't parse ls; you could simply do:

ls [^[:digit:]]*
ls [![:digit:]]*

Note that, bash supports both ^, and ! as pattern negation token inside character class while globbing.

If you don't want to depend on you locale:

ls [^[0-9]]*
ls [![0-9]]*


I have a problem with my Ubuntu-server , It is burce-forcing other servers and I was unable to solve till now.
Server is newly rebuilt but there are still PHP files from old server.

You effectively copied the actual malware from the old to the new server. You don't need firewall rules. You need to take your site offline now and fix the problems before you take it online again.
This probably involves a clean wordpress install, copying over parts of wp-content that has media content, and manually reading through a database dump to check for unknown users, options, php content and so forth.
Firewall rules to limit this is the wrong approach.


Searchable Clipboard Manager, like ctrl-r in bash

Introduction

As stated in the comments, I've written a simple clipboard manager indicator with use of Python 3 and a few zenity dialogs, which allows manipulating clipboard contents, as well as has search functionality.

Search functionality, in particular, makes use of Python's re module, which means you can use regex expressions for more fine-grained search. Each text entry has 4 options in its submenu: insert text into clipboard, append text to the end of what's currently in cliboard, prepend text to the beginning of current contents, and remove it from history.

Installation

In terminal , run the following commands:

sudo add-apt-repository ppa:1047481448-2/sergkolo
sudo apt-get update
sudo apt-get install indicator-bulletin

Demo

In the animation below you can see demonstration of text being copied, clipboard appended to with the indicator, and finally the test string is searched via simple search dialog. The found contents are displayed in a simple text view dialog with timestamp in user's locale (if it's set). The found text then can be copied via selecting text and using standard Ctrl+C  shortcut.

In case anybody is wondering:

animation is made with silentcast app
desktop and icon theme are Ubuntu Kylin theme, 16.04 version
Yes, that's Ubuntu (16.04) with launcher on the bottom.

Further development

The indicator was made in one day, thus it is fairly minimalistic in nature as of right now. In future there will be additional features added, such as preferences dialog. The menu length and text width are currently hard-coded to 10 items in the indicator and 30 characters max for each entry.

If you want to make a feature request, please submit an issue ticket on project's GitHub page, where its source code is also available.

Updates:

February 14,2017:

Implemented file operations feature - loading a text file into clipboard and writing clipboard contents to file.
Implemented displaying range of entries by date. The option calls for zenity forms dialog which requires starting and ending date in YYYY/MM/DD/HH:SS format. Effectively, this is log reading within date range, same as this
couple bug fixes

February 15,2017:

Added editing submenu. Users now can convert clipboard contents to upper/lower case, trim words/characters from beginning or end of the text, and replace expressions(uses python's re regex).

February 17,2017:

Added option for opening a history item in text file ( similar to bash's fcedit). So far this only opens default program set for the plain-text filetype.
couple improvements and bug fixes.

February 19,2017:

Added base64 operations (encode/decode).

March 3rd,2017:

Added "Pinned submenu" and ability to "pin" specific items from clipboard history. Code refactored, certain parts rewritten for repeated use.


Connect to invisible SMB Server by bash script

It's likely failing because the option string produced by your printf contains whitespace.

In any case, it's considered bad practice to include variable expansions directly inside a printf format string. Instead, use %s and move the variables outside as arguments:

printf '//abcde.fghi.de/jklmn /media/localfolder cifs domain=domainname,username=%s,password=%s,iocharset=utf8,sec=ntlm 0 0\n' "$user_var" "$pass_var"

Having said all that, I really question the idea of editing /etc/fstab on the fly like this - why not simply call mount with the relevant parameters?

sudo mount -t cifs -o domain=domainname,username="$user_var",password="$pass_var",iocharset=utf8,sec=ntlm //abcde.fghi.de/jklmn  /media/localfolder


Does snappy packaging make a convenient, portable, offline MediaWiki possible (say, on a thumb drive)?

You can use Kiwix for offline read-only MediaWiki snapshots. If you want a proper functional MediaWiki, probably the least painful way to go about it is MediaWiki-Vagrant - create the wiki on a virtual machine and save a snapshot of that virtual machine on a stick. (This will have a huge size and performance overhead but with typical CPUs and USB stick sizes these days that's not much of a problem.) You will still have to install the software which runs the virtual machine (Vagrant and VirtualBox) on the real machine, but there are OS packages for that.


Do I need to create a new user on my local Linux box?

Ubuntu is set up from the start to have root disabled with no possibilities for root to log in. The only way to become root is by using sudo or polkit.

It might be a clever idea in some cases to create a secondary user for the LAMP stack but its not mandatory needed if you only plan to use it as development platform which you mostly will only access locally.

You might want to look into usage via VM (KVM/qemu, Virtualbox, VMWare) or other container formats like docker and co.

This would give you the ability to have a real server environment running and more fine grained access controls, as well the option to shut the server down in the times you not need it.


Can't find how to change Xbmc mouse speed

There is no setting in xbmc to change the mouse speed. Changing the speed would require changing the code for xbmc.

I checked both the settings panels and all the xml settings files in the user data folder.


How to extract initrd from ubuntu-20.04-live-server-amd64.iso

/usr/sbin/update-initramfs calls /usr/sbin/mkinitramfs, which calls

cpio --quiet -R 0:0 --reproducible -o -H newc | lz4 -9 -l

where the lz4 is coming from /etc/initramfs-tools/initramfs.conf

reversing that into

cat /boot/initrd.img-5.4.0-26-generic | unlz4 -9 -l | cpio -i -H newc

fails though.

cat /boot/initrd.img-5.4.0-26-generic | file -
    /dev/stdin: ASCII cpio archive (SVR4 with no CRC)

keeps persisting it's a cpio archive, but

cat /boot/initrd.img-5.4.0-26-generic | cpio -i -H newc

still ends up in the same AuthenticAMD.bin.
Maybe somebody else can build on this?

Edit: nope. According to https://unix.stackexchange.com/a/511224/44864
The answer is

 unmkinitramfs -v initrd.img-5.4.0-26-generic .


You can setup your own keybindings using an init.el file inside your .emacs.d. Just copy and paste the following code in your startup script:

(define-key global-map [?\s-x] 'kill-region)
(define-key global-map [?\s-c] 'kill-ring-save)
(define-key global-map [?\s-v] 'yank)

If you don't know the names of the commands executed by a key sequence, you can discover using C-h k and then pressing the key binding you want to know about. Then you just use the define-key to create new keybindings for this command.

You can also unmap using global-unset-key. Make sure your key bindings don't conflict with the operating system.

More on this:

Mastering Key Bindings in Emacs


How to merge a pdf file as a first page into many pdf files?

Let's assume that all of your "4000" .pdf files are located in a single directory (for example files ) and the license.pdf is directly outside this folder. Then you could easily iterate through each file and concatenate it with your license. This script should do the trick:

#!/usr/bin/env bash
for current in files/*
do
    pdftk license.pdf "$current" output "edits/$current"
done

At the end all modified files will be contained in the folder edits, which is at the same level as files.

Make the script executable with chmod u+x name-of-the-script and run it with ./name-of-the-script and don't forget to place it in the same directory where the license.pdf file is stored.


Couldn't get back to my Ubuntu with my password

Start by reinstalling your OS after backing up desired data.  Completely disconnect it from the Internet while doing this.  Post re-install here's a simple check list.

Set strong passwords.
Configure your firewall (Ubuntu doesn't configure a firewall initially by default).

Beyond that, there are numerous guides on securing servers which directly apply to Desktop Linux.  Check out openstack-ansible-security.


Mysterious __dummy__ file appeared in my Downloads folder

From the command line, it's easy.

Rerun the extraction under strace (read man strace)

 strace -e trace=file unzip "the zip file" |& tee strace.log

This will show all the "file" operations, including the creation of your dummy file.


Setting up OGRE 3D and cmake for Ubuntu 14.10

The following command in terminal

sudo apt-get install libogre-1.9-dev cmake

should get you everything you need to develop with Ogre and also install CMake.

You might want to follow a guide or tutorial to get a grasp of Ogre first.

And especially make sure you're comfortable with the code before you mess with a build system like CMake - unless your IDE forces it on you, in which case it should do most of the work for you as well. If it forces CMake but doesn't do most of the work, for you, throw it away and use Gedit for editing and GCC directly for compiling.


Can I run the keyboard layout GUI of the Ubuntu installer without having to follow the installation process?

I'm not aware of any way to use the GUI of the installer after the installation.

In Xubuntu you can go to Settings -> Keyboard -> Layout, uncheck "Use system defaults", and add the layouts you want to test. Then you can add the Keyboard Layouts indicator to the panel and use it to switch between the layouts you added.


installation of ubuntu off line and alongside windows XP

Ubuntu can be installed with out internet as well as run with out it.  However if u wanted updates on install u would need internet.


How to Link Google Drive, Dropbox, or other Folders Into Encrypted Home Folders?

Another option that might be of interest for you, would be symlinking it:

ln -s /home/username/Dropbox/Documents /home/username/Documents


White line appears around windows after driver update

I had the same thing.

In terminal write sudo apt-get upgrade, this should fix it.


Cannot set tp_smapi thresholds on a Thinkpad

You should do as showing below:

sudo sh -c 'echo XX > /sys/devices/platform/smapi/BAT0/stop_charge_thresh'

But I also suffer from trouble in ThinkPad X201s + Ubuntu 11.10.

Battery keeps discharging while I connect my ThinkPad X201s to AC adapter.
Before update Ubuntu, charge_thresh values are shared with Windows configuration.
But after upgrade, the value of threshold are initialized to 95 & 100 while it is
configured to 75 & 95 in Windows.


One quick method of doing this is in Terminal. Which can be done by pressing Ctl + Alt + T Enter the following commands.

sudo apt-get update

sudo apt-get install ubuntu-server


Ubuntu 13.4 starts super-slow (90 seconds) on a 2x 2GHz / 4GB Ram laptop

well, the chart is pretty self explanatory, as expected in any configuration the usual bottleneck is the HDD or any other I/O peripheral, especially on notebook machines, that chart is almost all pink and the pink part is almost always hitting the roof.
You probably have a slow 5400 rpm HDD with an really high seek time.

Your CPU it's also a low end one but this doesn't really matter.


As DigitalOcean support says:
"Our engineers are aware of the issue affecting proper keystroke entry in the web console, and they are working on overhauling the experience. In the meantime, we recommend that you access your Droplet via SSH."


How to transfer public and private PGP keys to another computer?

Assuming that you are using GnuPG on Ubuntu...

First, you should export them:

gpg --export-secret-keys <keyid>  >key.gpg
gpg --export <keyid>  >>key.gpg

Then you should transfer this file to the Mac via a secure channel and import the keys on the recipient. You should be able to import the key via the graphical GPG Keychain, or through the command line (gpg --import key.gpg).

If you need to use a insecure channel to transfer the private key, such as email or other network based channels (where you don't have proper certificates ensuring that you are really communicating with the correct machine), you must use PGP (or some other method) to keep you private key secure:

On your Mac, create a temporary key pair send the public part to your Ubuntu machine
On your Ubuntu, check the fingerprint of the received key and encrypt 'key.gpg' with it, also signing it with you own key
Send both the Ubuntu public key and the encrypted 'key.gpg.gpg' file to the Mac
Again on your Mac, check the fingerprint of the received key and decrypt/verify the received 'key.gpg.gpg' file


Problem installing Ubuntu on USB drive with "no root file system is defined"

Select the Partition in which  You need to install.
Unallocate it by clicking the  - sign.
Create Partition of EXT 4
Remember to Set the  / in the last option of Partition Creation.
Continue to Install


Gnome dependency problems with Nvidia drivers

I found the solution.

I'm not sure what exactly was the problem, but this issue seems to have disappeared on a fresh install of 16.04. Perhaps they updated the dependencies properly in it? I'm not sure. But I can personally confirm that this is no longer an issue in 16.04


Network UNCLAIMED Realtek d723 Ubuntu 16.04

With a temporary working internet connection by ethernet, tethered or whatever means possible, open a terminal and do:

sudo apt update
sudo apt install build-essential dkms git
uname -r

The last command will give you your kernel version; for example 4.13.0-32-generic. If your kernel version is 4.11 or higher, continue with the following:

git clone -b 4.11-up https://github.com/jeremyb31/rtl8723de.git
sudo dkms add ./rtl8723de
sudo dkms build rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414

If your kernel version is 4.10 or lower, then do:

git clone -b 4.10-down https://github.com/jeremyb31/rtl8723de.git
sudo dkms add ./rtl8723de
sudo dkms build rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414

In either case, reboot and your wireless should be working.

EDIT: The fact that your dkms status shows ‘built’ and not ‘installed’ suggests that there were problems, most likely errors, in the process I suggested. These errors cannot be ignored; they must be identified and fixed before the driver will build and install properly. Let’s start over. If, at any time, there are errors STOP and post them so we can fix it and proceed.

From the terminal:

sudo dkms remove rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414 --all
sudo rm -rf rtl8723de
git clone -b 4.10-down https://github.com/jeremyb31/rtl8723de.git
sudo dkms add ./rtl8723de

If there are errors here, STOP and report them.

sudo dkms install rtl8723de/5.1.1.8_21285.20171026_COEX20170111-1414

If there are errors here, STOP and report them.

If all goes without error, please check again:

sudo dkms status

We hope you see:

  rtl8723de, 5.1.1.8_21285.20171026_COEX20170111-1414,
  4.10.0-28-generic, x86_64: installed

If so, try:

sudo modprobe 8723de

Any improvement?


Internal mic not working with Skype 4.0.0.8 in12.04

It's solved. The problem was with pulseaudio, so i made an script like this:

#!/bin/bash
killall pulseaudio
skype

to kill pulseaudio before invoking skype. I also had to create a file ~/.pulse/client.conf with the following line:

autospawn=no

to avoid pulseaudio to restart automatically when i invoke the kill command.

cheers!!!


Use sed to use "find and replace" for each second occurrence

sed -E s'/(.*[^-])(-?0\.)/\1    \2/' 999.dat

The *  is greedy and eats up as much characters as possible so the \. matches always the last one of the line. The [^-] ensures that the optional - of the second number gets into the second group.


Run the following command to install that driver (swrast_dri.so):

sudo apt-get update
sudo apt-get install libgl1-mesa-dri libgl1-mesa-dri:i386

Please post any errors, thanks!

Usually, when I've seen this error, running:

sudo apt-get clean
sudo apt-get update
sudo apt-get dist-upgrade

fixed the issue.

However, sometimes you may need to try and install (or uninstall) stubborn applications individually to get things done.

To understand the message, install the needed dependencies individually to see what the issue is (or this may fix the issue):

sudo apt-get install --reinstall libcheese-gtk23 libcheese7

If the next error message says blah blah blah depends on blah blah blah, try installing blah blah blah and go from there.


How to install mobogenie in Ubuntu 14.04

You could use Wine.
Wine enables Linux, Mac, FreeBSD, and Solaris users to run Windows applications without a copy of Microsoft Windows. Wine is free software under constant development.
You may get an older version of it in Ubuntu Software Center.
After installing Wine, install the .exe file of Mobogenie via it.
If you've got a machine which has atleast 2 GB of RAM and a fast enough processor it should run smoothly.


How can I enable a repository or target temporarily and easily disable it without using vim/sed/etc?

If you already have or can install software-properties-common it gives you an awesome and simple command line tool to do exactly this. You may already have it if you have used a PPA (personal package archive) to install extra software on your system, otherwise you can run
sudo apt update
sudo apt install software-properties-common -y # the -y accepts a prompt for you

I ran into this while trying to install mbrola and the voices for it. The website suggested for grabbing these non-free components seems to be down, so I was looking for alternatives and finally figured out that they were packaged for Debian/Ubuntu, just not available in the default sources.
First, you can check your existing sources to see whether you have non-free or contrib enabled already. This command recursively '-r' searches for anything '' in all files matching sources.list* which includes sources.list.d/ and all files in it and prints out each line of each file preceded by the filename.
grep -r '' /etc/apt/sources.list*
# we'll also save this list to a file to easily see which files get updated
grep -r '' /etc/apt/sources.list* > /tmp/apt-lists-before.txt

Now to enable contrib or non-free, they are on separate lines because this tool requires you to only specify one at a time.
sudo add-apt-repository non-free
sudo add-apt-repository contrib

Then check your sources.list* files again.
grep -r '' /etc/apt/sources.list*
# we'll also save this list to a file to easily see which files get updated
grep -r '' /etc/apt/sources.list* > /tmp/apt-lists-after.txt
# compare the two lists
diff /tmp/apt-lists-*

If you are satisfied that it added the intended new targets, you can run sudo apt update and apt search mbrola to see an example of new packages available that weren't before.
sudo apt update
apt search mbrola

Now you can install the software you want, then disable the non-free or contrib sources afterwards, which will allow the software to work, but not automatically update. If a new version of some normal package causes issues with the non-free package, you can repeat this process to enable the non-free repository again and see if after sudo apt update there is an update for the package with sudo apt --upgradable.
sudo apt install mbrola mbrola-us1 -y # the -y accepts a prompt for you
sudo add-apt-repository --remove contrib
sudo add-apt-repository --remove non-free

See also this excellent Q&A that describes only allowing certain non-free packages to update while blocking the rest.
https://unix.stackexchange.com/a/534340/103652


'Permission denied' to the user who owns the directory

arm needs permissions on the parent, too. Try e.g.
chmod 775 /mnt/data

which gives arm (and anybody else) read- and execute permissons on /mnt/data. Note that for directories execute permission means permission to enter the directory.


how to make usb into 2 partition for use

Maybe you need to use the lsblk command first to see the disks and the partitions. If there is not something like sdb1, your partition operation is not correct.

Then you should do sudo mount /dev/sdb1 /media/user/somedir


I found out it appears in Ubuntu 14.04 as well. The thing is that in case brightness adjustment does not work, adding the option "acpi_backlight=vendor" in the GRUB_CMDLINE_LINUX_DEFAULT variable in the /etc/default/grub file is a popular solution which now causes the booting problem. Removing the option from the file and updating grub by running "sudo update-grub" solves the problem.


You shouldn't have to repartition the disk just to reinstall Ubuntu. It seems like you just have one partition for Ubuntu, and one Swap partition in an extended partition, which is a standard partitioning scheme for an Ubuntu installation.
You could boot the Ubuntu iso from the Grub menu. When you boot from the iso file, you will be able to press a key upon boot to get to the Live boot menu. Add the toram kernel option.
You will be able to choose whether you want to save programs or Home folder data or just erase everything and reinstall.
And importantly, make reliable backup before executing the procedure! Though nothing should go wrong if you ensure that you know what you're doing.


Dell studio 1555 overheating and fan problem

Yes, your first option would be to update the BIOS. Dell produces updates quite often and they solve issues such as powersaving related ones.

The most common reason why a computer overheats in Linux is that the DSDT tables of the BIOS are buggy for Linux. Some users have gone the extent of fixing the DSDT tables themselves, such as at HOWTO Fix A Buggy DSDT File

However, I recommend to apply the latest official BIOS update and check again.


The disk Burner softwares do not support burning of huge images .This at least applies to Brasero and K3B.

There seems to  be a workaround.Run these commands one by one

dd if=/dev/zero of=file.iso bs=1024 count=4589800
mkudffs file.iso  #your filename here
mkdir /media/tmpdvd # if you haven't already a directory
mount -o loop -t udf file.iso /media/tmpdvd
cp big_file /media/tmpdvd
umount /media/tmpdvd

Then try to burn the file using GUI or terminal as per your choice.

If the above method dosen't work, see the output of

ulimit -f

if it is not unlimited, run this command

ulimit -f unlimited


Ubuntu 18.04 - Show Bluetooth connected device battery status

You can go to settings>Power and there you should see connected devices and their battery


Mac OS X dual boot with encrypted Ubuntu LVM

I've never done anything like this but I would backup Mac OS X and install Ubuntu with encryption and LVM which is an option on the installer which will also wipe the disk. Then you can resize the encrypted Ubuntu (which you can look up how to do) so you have space to install Mac OS X. Then restart your Mac and hold alt on boot. Then you connect to internet. Then you'll see an internet recovery option, which you click and use restore from backup. Then you should have a dualboot. I think.


How to recover files lost after reinstalling Ubuntu?

It has been said that the files would be safe if I reinstalled and used the same username and password.

Whoever said that lied to you. Unless you had /home on a separate partition, and in the new install chose to not format that partition, your files are unrecoverably gone. And even if /home was separate, if it was encrypted I hope you backed up the encryption key. Otherwise the files are still gone.


You must download file, first.
This is download link eXtreme Burner for Ubuntu (Latest v.10.10):
http://www.extremeelectronics.co.in/software/BurnerAVR/xAVR_Ubuntu.tar.gz

second step, extract file.

enter folder xAVR :
$ cd xAVR

and you can run the program :
$ ./avrprog


14.04 to 16.04 upgrade goes wrong and freezes

Note: This method is a tad convulted, but hey, no GUI = command-line fu :)

Step 1: Locate the partitions where you want to copy

Run the command sudo blkid, you should get output similar to this:

...
/dev/sda1: UUID="gibberish" TYPE="ext4" PARTUUID="more gibberish"
/dev/sdb1: LABEL="MYUSB" UUID="NUMBERS" TYPE="vfat" PARTUUID="gibberish"
...

If you want to transfer to a USB, look for partitions with the vfat file system and a label containing the word "USB".

Once you have located the partitions you want to copy to, continue.

Step 2: Mount the partition(s)

You can mount the partitions like so:

sudo mkdir /mnt (if it doesn't exist)
sudo mkdir /mnt/usb
sudo mkdir /mnt/hdd
sudo mount [usb partition here] /mnt/usb
sudo mount [hdd partition here] /mnt/hdd

Step 3: Copy files

Let's say you wanted to copy over /home/bob/folder.

If you don't care about permissions and file ownership, you can use cp with the --recursive flag:

cp --recursive /home/bob/folder /mnt/usb/folder
cp --recursive /home/bob/folder /mnt/hdd/folder

If you do care about permissions and owners, use the rsync command:

rsync -ar /home/bob/folder /mnt/usb/folder
rsync -ar /home/bob/folder /mnt/hdd/folder

Step 4: Unmount the partitions

Once you're done with them, unmount them:

sudo umount /mnt/hdd
sudo umount /mnt/usb

Step 5: Complete!

You've backed up your stuff!


Is the Alternate Ubuntu installer still required for LVM or Software RAID setup?

The Ubuntu Server image has LVM and RAID, I think since 9.10. Go for the manual option at partitioning, you'll find it there.

If you want to have an Ubuntu Desktop on RAID/LVM, then you still need the Alternate image


Second network interface not showing up in Ubuntu 18.04

I switched which PCI slot the card was plugged into and upon reboot, it is now showing up both in lspci and ifconfig.


How do I revert back from sudo add-apt-repository ppa:xorg-edgers/ppa?

You can use ppa-purge as suggested on their launchpad page.

  ** Please use ppa-purge to remove this PPA. It is particularly recommended to do this before upgrading to a new ubuntu release! **

Thus, we'll install ppa-purge package:

sudo apt install ppa-purge
sudo ppa-purge xorg-edgers

What ppa-purge do ?

  ppa-purge - Disables a PPA and reverts to the official packages if applicable. For example, if I added the xorg-edgers PPA and installed the Nvidia drivers, if I do a ppa-purge on said PPA, it would not only disable the xorg-edgers PPA but also revert the NVIDIA drivers from the one in the PPA to the official ones found on the official Ubuntu repositories.

Quotes from this answer.


To install a Let's Encrypt certificate, use certbot utility. It is well documented.

You simple have to do:

sudo add-apt-repository ppa:certbot/certbot
sudo apt install python-certbot-apache
sudo certbot


Just follow this howto https://wiki.ubuntu.com/UbuntuOne/Tutorials/Windows and you should see your synchronised files in My Documents\Ubuntu One


How to request if some of the package is out of date

As you can see on the link you asked about, there are newer versions available on Ubuntu 12.10 and 13.04, respectively. You will need to build your own packages, install from source, or request a backport of the package.


Play sound through headphone jack while connected to TV

Open Pulse Audio Settings and switch output to the headset


non-US external keyboards with ubuntu touch

My current answer is no. I can't get my UK Dell USB keyboard to work with my Meizu 4. I have reported a bug:

USB keyboard not recognized Meizu 4
Bug #1488899 reported by fcolcord on 2015-08-26

No one else has reported a similar problem, so I think the bug is asleep until someone else verifies it. Please go to that page and say the bug affects you, if it does.


I've recently had installation problems during a 12.04 installation process on an older machine. I found that installing from the "alternative install CD " which will give you a text based installer, I could get it done without hiccups

http://releases.ubuntu.com/precise/


This is a complex topic that is hard to give a true "Patched" or "Not patched" answer.  So, I will provide you the very inaccurate and useless short answer, and a less brief summary that summarizes the rest of the info I provide.

The very inaccurate short answer is "Yes and no", but it doesn't give you a clear idea of what the actual situation is.

I'm not sure what architecture AWS uses, but my guess is that it's an i386 or amd64 architecture.  Patches for Spectre variant 1 and Meltdown are in the kernel.  But Spectre Variant 2 requires updated stable firmware / microcode from the manufacturers - both Intel and AMD.  Therefore, though the kernel contains mitigations against the issues, the actual CPU firmwares need updated.  And therefore, Spectre variant 2 is not completely patched.

However, the above summary is not really an accurate portrayal of the current state of patching against these issues - it's just a very basic summary.

So, for that reason, I'm taking the data provided from the Security Team's knowledge base, and making it a human-understandable summary of the page as it was on March 22, 2018 at 09:48AM UTC-4.  I also am only focusing on 14.04 and later versions, because Precise is End of Life unless you pay Canonical for the Ubuntu Advantage for 12.04 Precise systems, and is mostly irrelevant for people running Precise without this paid support.

Note that for the Spectre and Meltdown issues  to be properly addressed in all releases, both the Kernel and the CPU Microcode sections must have mitigations and updates released and incorporated.  This is why Spectre Variant 2 is not really 'patched' yet, per-se.

Kernel:

Patched for Spectre Variant 1.
Patched for Meltdown.
Spectre Variant 2:

Kernel contains mitigations
Kernel mitigations alone aren't enough, CPU firmware/microcode updates are needed.

CPU Firmware/Microcode:

ppc64el and s390x processor architectures patched, updates available from IBM.
armhf and arm64 are mostly unaffected, there are only a very small number of chips affected by this.
i386 and amd64 do not have stable releases to their microcode addressing this issue.

Intel had released microcode updates, but these were reverted due to the introduction of system instability issues, details in USN-3531-2.
AMD released a statement on March 20th that they are in the process of developing and staging mitigations for Spectre and Meltdown, but has not yet released a stable version of microcode.
Summary: No stable release of microcode updates has been made containing the Spectre and/or Meltdown code updates.

Userspace Mitigations:

Some programs and libraries have mitigations against Spectre and Meltdown built-into their code to prevent exploitation of the issues by the programs or libraries themselves:

Firefox
WebKitGTK+
NVIDIA graphics drivers
QEMU
libvirt

Cloud Images (this might not include AWS, and I have not checked):

Trusty, Xenial, and Artful cloud images after 20180122 as their serial include patches in the images.  Per the above other sections, though, as Cloud Images still have to obey the rest of the patch rules and such from above.

This answer was last updated on: March 22, 2018 10:02AM


LibreOffice 5.1 black text issue within dialogs

please refer to this Launchpad bug for details.
Corrupted Fonts with AMD GPU BUG

Suffice to say according to the chatter in that bug-thread; that you can fix it by purging your current LibreOffice and installing the prerelease 5.2.0
LibreOffice 5.2

Alternatively you can wait for Ubuntu to release "xorg-server 1.18.4" on their repo. It is earmarked for Yakkety Yak (Ubuntu 16.10) and will be backported to 16.04.


Clone an Ubuntu machine with software RAID

I am sorry with providing no real answer, but I think I can provide at least some help as I wrote a script to copy ubuntu systems. I did not published this script though, because it is not perfect until now! So please be careful!

Read all configuration parameters and comments carefully. Maybe you don't want to use the script at all, but investigate the skipped paths only that are not possible/needed to rsync.
Most important step is to manually adjust the /etc/fstab after successfully copy of the system.
Also I don't quite understand - you wanna clone into a running system?? I am not sure if this will work.

Nevertheless, here is the script:

http://www.nskcomputing.de/index.php?section=Download&id=copytux

But again: the script is in beta stage, be very very careful!

Regarding the hardware raid, try to find out whether the raid controller is supported natively or if there is an additional driver or kernel module to support the controller.


As was stated by user535733 in the other answer, this package was dropped from Debian and in turn removed during the Focal development cycle.

The following information after this notice was all obtained from Debian Bug #814894 and corresponding title edits.  The aforementioned Debian Bug number was obtained via the Launchpad Publishing History for the mididings source package.

Since 2016, the Package Maintainer in Debian had orphaned mididings and nobody picked it up for ongoing maintaining.  Since that time, additional findings were made about the package:

Orphaned 3+ years earlier (initial 2016 orphan by maintainer)
Dead Upstream (means that the upstream project is dead with no maintainers or code updates)
Low package popularity rating (very few installations in Debian)
Python 2 Only (EOL / Obsolete / Removed version of Python)

Because of this, it was removed from Debian - with the Python 2 death this year, Python 2 only packages were heavily scrubbed in Debian.  These changes trickled down to Ubuntu, and the package was removed.
The only way to install it would be to download the package from the Bionic repositories and manually install it.  However, there is no guarantee the package will work, or that the dependencies are available, given the Great Python 2 purge that has been going on upstream in Debian.


That echo could come from your microphone in your headset. You need to mute the microphone sound.

Open a terminal and run the alsamixer program. Use arrow left/right keys to move between sliders and press M for (un)muting a slider. Press Esc when done and run exit to close the terminal.


OK, I got it working -
//Edit : (My original fix wasn't actually what fixed it)

Oddly enough, one website suggested:

ln -s /opt/Aptana_Studio_3/AptanaStudio3 /usr/local/bin/aptanaS3

Which actually seems to be precisely what fixed the problem...
Running Aptana via aptanaS3 instead of /opt/Aptana_Studio_3/AptanaStudio3 actually fixed the problem.
I didn't originally mention it, because I thought I was just making a shortcut...

This is everything else I did, albeit I don't think any of this matters:

Added:
-Dorg.eclipse.swt.browser.DefaultType=mozilla

to /opt/Aptana_Studio_3/AptanaStudio3.ini at the very bottom...

Also did this, which I learned from here

wget -O xulrunner.deb http://launchpadlibrarian.net/70321329/xulrunner-1.9.2_1.9.2.17%2Bbuild3%2Bnobinonly-0ubuntu1_amd64.deb && sudo dpkg -i xulrunner.deb


How can I run Midnight Commander opening an ftp connection on launch?

You can:
mc leftpanel [ rightpanel ]

left panel:
xfce4-terminal -x mc   ftp://user:password@example.com

right panel:
xfce4-terminal -x mc . ftp://user:password@example.com


Why am I getting a syntax error from | in this script?

In the line

echo -e  "${green}      | | | \__ \__ \"

the \ before the " removes the special meaning of the " and makes it a normal character that doesn't end the string. So the string continues to the next line until the " before ${green} and the following ${green}      |_| |_|___/___/ isn't quoted any more, which causes the error.

Add a space after the \ to prevent it from escaping the ":

echo -e  "${green}      | | | \__ \__ \ "


Grub always fails to install, furthest I get is grub> prompt

In my opinion, you try to install by selecting 'continue without a bootloader', when you finish, reboot your computer with a liveCD or LiveUSB again. after being on the desktop, try to reinstall grub with the steps:
mount ubuntu partition that you installed earlier. you can click on places > your-ubuntu-partition
open terminal, run:

sudo chroot /media/your-ubuntu-partition
sudo grub-install /dev/sda
sudo update-grub

close the terminal, and try to reboot it.


Preserve screen backlight intensity over sleep

One way is to edit /etc/default/grub and in GRUB_CMDLINE_LINUX_DEFAULT, add acpi_backlight=vendor, and run sudo update_grub. After you restart, you should see that /sys/class/backlight/acpi_video0 disappears and /sys/class/backlight/intel_backlight remains. KDE will then use this to control the brightness.

If the above doesn't work, you could have a script that saves the value of intel_backlight to a file upon sleep and restores the value on wakeup. Scripts in /etc/pm/sleep.d run on suspend/hibernate and thaw/resume.

Note that you'll need to determine whether you're going to sleep or resuming. $1 contains one of the above four values (suspend, hibernate, thaw, resume), which you can use to determine what to do.


How to enable ssh root access ubuntu 16.04

on Ubuntu 16.04

ensure you have openssh-server server installed
 sudo apt-get install openssh-server

sudo nano /etc/ssh/sshd_config

change

PermitRootLogin prohibit-password

to

PermitRootLogin yes

or sudo sed -i 's/prohibit-password/yes/' /etc/ssh/sshd_config

in order to PAM authentication add

AllowUsers root

or sudo echo "AllowUsers root" >> /etc/ssh/sshd_config

sudo service ssh restart

works fine

in order you don't know your root password set new with privileged user

sudo passwd root

  and you may want to get rid of password prompt in safe way what may be useful approach for sth like rsync, ansible and so on, so probably

from where ever you want to connect

ssh-keygen; ssh-copy-id -i ~/.ssh/id_rsa.pub root@YOURHOST

enter the root pass you have just set and DONE

ssh root@YOURHOST


Is your machine using an EFI BIOS?

If so, you'll want to make sure that you created your image using a program that can write a EFI bootable image.  unetbootin is not one of these programs.

You can do this via terminal in Ubuntu by typing

dd if=/dev/sdb1 of=/home/user/path/to/iso.iso

Make sure to change /dev/sdb1 to the location of your thumb drive/cd media.


If you still have Windows on your PC, you can try Wubi. I don't recommend it because it doesn't support 13.04+, and it isn't very compatible with Windows 8. But if there is really no way to get the CD/flashdrive version to work, you can give it a shot.

Wubi is a program that basically installs Ubuntu within Windows, so you would get a dual boot PC. The downside to this is that you can't delete Windows, or you'll delete Ubuntu as well. That said, Windows treats Ubuntu like a program so you can uninstall Ubuntu from Windows like you would with any other software.

For more information visit https://wiki.ubuntu.com/WubiGuide


Script adding launchers to the top gnome panel

Just to make script easier, made assumption:

default top panel is 'top-panel-0' got from:

gsettings get org.gnome.gnome-panel.layout toplevel-id-list

Not many icons already up there in the panel, just to avoid overwriting other object with same index (ex: 'object-0-9'), got from:

gsettings get org.gnome.gnome-panel.layout object-id-list

Objective script:

gsettings set org.gnome.gnome-panel.object:/org/gnome/gnome-panel/layout/objects/object-0-9/ object-iid 'PanelInternalFactory::Launcher'
gsettings set org.gnome.gnome-panel.object:/org/gnome/gnome-panel/layout/objects/object-0-9/ toplevel-id 'top-panel-0'
gsettings set org.gnome.gnome-panel.object:/org/gnome/gnome-panel/layout/objects/object-0-9/ pack-type 'start'
gsettings set org.gnome.gnome-panel.object:/org/gnome/gnome-panel/layout/objects/object-0-9/ pack-index 1
gsettings set org.gnome.gnome-panel.launcher:/org/gnome/gnome-panel/layout/objects/object-0-9/instance-config/ location '/usr/share/applications/gedit.desktop'
gsettings set org.gnome.gnome-panel.layout object-id-list "[`gsettings get org.gnome.gnome-panel.layout object-id-list  | awk '{ gsub("\[|\]",""); print;}'`, 'object-0-9']"

To reset/remove all launchers, I couldn't get gsettings reset to work with data stored without schema (API may be not supporting that), whereas dconf reset does:

for o in $(dconf list /org/gnome/gnome-panel/layout/objects/); do if [ ! "${o##object*}" ] ; then dconf reset -f /org/gnome/gnome-panel/layout/objects/$o; fi; done
dconf write /org/gnome/gnome-panel/layout/object-id-list "`dconf read /org/gnome/gnome-panel/layout/object-id-list | awk '{ gsub(/(, [:\47]object-[0-9]-[0-9][:\47]|[:\47]object-[0-9]-[0-9][:\47], )*/,"");  print; }'`"

Notes:

Better to use dconf-editor to see or make quick key changes for testing.
Use monitor dconf changes &  what the script is doing:

dconf watch /org/gnome/gnome-panel/


Why Same File Shows Different Sizes in Different Operating Systems

Windows assumes that there are 1024 Bytes in a Kilobyte unit, and 1024 Kilobytes in a Megabyte unit.  While Ubuntu assumes, a 1000 bytes constitute a Kilobyte (KB) unit, 1000 Kilobytes for a Megabyte (MB) and so on.

Windows is using the ‘binary prefix’, and  Ubuntu or GNU/Linux, is using it in its ‘proper’ foam.

  The IEC and NIST standardized, and changed the symbols into …

  In usage, products and concepts typically described using powers of
  1024 would continue to be, but with the new IEC prefixes.

  For example, a memory module of 536870912 bytes (512×1048576) would be
  referred to as 512 MiB or 512 mebibytes instead of 512 MB or 512
  megabytes. Conversely, since hard drives have historically been
  marketed using the SI convention that “giga” means 1000000000, a “500
  GB” hard drive would still be labeled as such.

  According to these recommendations, operating systems and other
  software would also use binary and SI prefixes in the same way, so the
  purchaser of a “500 GB” hard drive would find the operating system
  reporting either “500 GB” or “466 GiB“, while 536870912 bytes of RAM
  would be displayed as “512 MiB”.wikipedia

So to answer your first question, use the size that's based on the fact that a MB is 1024KB.  As far as the second question, I'm not aware of such a tool.


Terminal Transparency in Ubuntu GNOME Malfunctions

I have now upgraded to GNOME Version 3.12.2 and to my surprise, there isn't a background tab anymore.

Reason:
I did some research and found out that the background transparency feature has been removed due to complications. Read it below from Allan Day :

  I've spoken to Christian and he has filled me in on the background to
  this issue.

  The ability to set background transparency was removed as
  a part of a much larger clean up of the gnome-terminal code base. This
  modernisation effort is much needed and it should be remembered that
  the terminal has an old and complicated code base. Background
  transparency was also known to cause a range of performance issues,
  including slowness and memory leaks.

  Given the number of active terminal developers, the need to clean up the code base and known bugs
  with background transparency, it was decided that the resources were
  not available to maintain background transparency and keep the quality
  to the required level.

  We understand that some users are disappointed
  by the disappearance of this feature, and we hope that they understand
  that this decision was made to enable other improvements to the
  terminal code, and that it will lead to other improvements in the long
  run. While Christian’s initial response could have been better, he has
  responded in detail in private mail and I suspect that he was simply
  tired of the issue.

Source: Bug 698544, Comment #45

Solution:
However, I have found a resolution to this issue by installing terminator sudo apt-get install terminator

Done


Can I use amd64 installers on Intel based systems?

AMD64 is for systems with 64 bit architectures (both Intel and AMD), whilst i386 is for 32-bit architectures (both Intel and AMD). 64 bit systems will run i386 version of Ubuntu, but not the other way around.
Based on your Motherboard, I would assume your CPU is 64 bit?
Have a look at the following post - My computer boots to a black screen, what options do I have to fix it?

Black screen or "you need to load kernel first" and "can not read
file/cd0"
errors when installing to an UEFI capable machine: Ubuntu's
installer when attempting to run in UEFI mode will hang and stop due
to different manufacturers implementing the UEFI specification in
different ways will hang differently. To identify if your machine is
booting installer UEFI mode you will see
REF: UEFI Community Ubuntu Documentation Section 2.4
If your machine is CSM capable (which is a full UEFI implementation
with an emulated BIOS layer) after selecting any option from grub list
system will hang at a black screen. The picture above actually only
confirms DVD/USB booted using UEFI and there will be some means in
firmware settings to ensure drives are booted in order to make UEFI
installer run - the solution to which may possibly be as simple as
ensuring SATA set to AHCI - check your vendors manual to check this.
Also check UEFI Community Documentation Section 2.3 for more details.
What you need to check is first disable SECURE BOOT in firmware
settings. If that does not get Ubuntu installer running - Try
disabling anything mentioning UEFI in firmware settings. Or If you can
not find UEFI settings then enable CSM - this will disable the UEFI
booting of installer and then allow a legacy/bios install of Ubuntu.
Installing grub-efi afterwards will allow UEFI to be re-enabled. Again
refer to UEFI Community Ubuntu Documentation this time at Section 4
Some machines use a full BIOS with an emulated UEFI layer which may
throw errors as described ie "you need to load the kernel first" and
"can not read file/cd0" Not all of these machines implement Secure
Boot. Simply selecting UEFI in BIOS settings will configure UEFI mode
on hard drives. The information above may still be relative to your
machine though regarding this. There is no solution for these errors
and the workaround is to disable UEFI to enable Ubuntu installer to
run in legacy mode. After which boot-repair can be used to install
grub-efi which then allows/needs UEFI switched back on before Ubuntu
will boot using UEFI. Once again referring to UEFI Community Ubuntu
Documentation at Section 4


"No application Data found" in Ubuntu software on 16.10

From the Updates tab, click on the refresh icon in the very top left and wait for it to refresh and it should populate the data.


gateway4 wants a scalar and you gave it an array. Try gateway4: x.x.126.1, with real numbers instead of x.x, of course.

See the Netplan reference documentation.


NVIDIA GeForce GT 750M with Bumblebee on Ubuntu 13.10 giving error

I have Acer Acpire V5 with GeForce GT 750M and Haswell. And optirun say the same error on first run. But on every second run it works fine.

$ optirun glxgears -info
[ 6640.693237] [ERROR]Cannot access secondary GPU - error: [XORG] (EE) NVIDIA(0): Failed to initialize the NVIDIA GPU at PCI:1:0:0.  Please
[ 6640.693272] [ERROR]Aborting because fallback start is disabled.
$ optirun glxgears -info
GL_RENDERER   = GeForce GT 750M/PCIe/SSE2
GL_VERSION    = 4.3.0 NVIDIA 319.76
GL_VENDOR     = NVIDIA Corporation
...

Bumblebee 3.2.1, Xserver-intel 2.99.906, Linux kernel 3.13, Mesa 10.1.0.


Terminal starts fast, but takes time to get ready

For anyone having the same problem, maybe this is what's happening to you as well if you also use node:
After temporarily moving my ~/.bashrc file to another folder and restarting the system to identify if the lag was being caused by my user configs or if it was system-wide, the prompt was immediately ready when I launched the terminal. Then I found out that the nvm install adds some snippets to ~/.bashrc, and this is what causes the prompt loading lag in terminal.
After some digging I found a solution here.
I hope it helps you as well.


How to confirm if undervolt is working in Ubuntu?

The readme provided explains it:

Run intel-undervolt read to read current values and intel-undervolt apply to apply configured values.

The output will show applied settings. Run intel-undervolt read first to check, then intel-undervolt apply, followed by another intel-undervolt read to verify that new settings is in fact applied.


Do I have to create a DVD for install or can I use a CD-R?

You sure can. Ubuntu has done a good job of keeping their iso files small enough to fit on a standard 700MB CD. Just make sure the iso file you use is less than 700MB (Ubuntu 12.04 is about 670) and you will have no problems.


awk '{print $2}' file_name | sort | uniq -c | sort -n | awk '$1>1 {print $2}' > duplicates
for x in $(< duplicates); do grep -n $x file;
done

so there if you have the ID's in the second column then it will print out the Duplicates ID's

Note: In the file_name ,place your file name .


Can I directly download audio using youtube-dl?

Here is a recent article in webupd8.org that explains how to use youtube-dl to directly download audio instead of first downloading video+audio and then extracting audio using -x. Unfortunately, the search facility that Maythux asked for here isn't offered. But it is still worth a look:
Video Downloader youtube-dl Gets Support For Separate Audio And Video YouTube DASH Streams

Basically, download the latest version of youtube-dl from source or from the ppa offered in the link above but not from the Software Center.

Then, if you already have the video link ...

Run, as example:

youtube-dl -F http://www.youtube.com/watch?v=HRIF4_WzU1w

This will list the various download formats available for this url (audio and video).

$ youtube-dl -F http://www.youtube.com/watch?v=HRIF4_WzU1w
[youtube] Setting language
[youtube] HRIF4_WzU1w: Downloading webpage
[youtube] HRIF4_WzU1w: Downloading video info webpage
[youtube] HRIF4_WzU1w: Extracting video information
[info] Available formats for HRIF4_WzU1w:
format code extension resolution  note
171         webm      audio only  DASH webm audio , audio@ 48k (worst)
140         m4a       audio only  DASH audio , audio@128k
160         mp4       192p        DASH video
133         mp4       240p        DASH video
134         mp4       360p        DASH video
135         mp4       480p        DASH video
17          3gp       176x144
36          3gp       320x240
5           flv       400x240
43          webm      640x360
18          mp4       640x360     (best)

Now, choose desired audio format. I went for 140

Run:

youtube-dl -f 140 http://www.youtube.com/watch?v=HRIF4_WzU1w

$ youtube-dl -f 140 http://www.youtube.com/watch?v=HRIF4_WzU1w
[youtube] Setting language
[youtube] HRIF4_WzU1w: Downloading webpage
[youtube] HRIF4_WzU1w: Downloading video info webpage
[youtube] HRIF4_WzU1w: Extracting video information
[download] Destination: Martin Luther King - I Have a Dream on August 28, 1963 [Sous-titres & Subtitles] [FULL SPEECH]-HRIF4_WzU1w.m4a
[download] 100% of 15.19MiB in 00:04

That's it.


Do you want to Suspend to RAM or Disk? (suspend to RAM is faster and requires power ONLY to ram)?

More details:

pm-suspend
           During suspend most devices are shutdown, and system state is saved
           in RAM. The system still requires power in this state. Most modern
           systems require 3 to 5 seconds to enter and leave suspend, and most
           laptops can stay in suspend mode for 1 to 3 days before exhausting
           their battery.
pm-hibernate
           During hibernate the system is fully powered off, and system state
           is saved to disk. The system does not require power, and can stay
           in hibernate mode indefinitely. Most modern systems require 15 to
           45 seconds to enter and leave hibernate, and entering and leaving
           hibernate takes longer when you have more memory.

  NOTE: there is also a hybrid mode which is in between suspend to RAM and Disk.

Find what states are supported by your laptop, for example (supports both to ram and disk):

cat /sys/power/state
mem disk

You can do it from command line anyway:

Option 1: use pm-utils (need to install the package and user needs to have privilege to do suspend)

Suspend to RAM: sudo pm-suspend

Hibernate (to Disk): sudo pm-hibernate

Option 2: directly change sysfs (requires root privilege)

Suspend to RAM: echo "mem" > /sys/power/state

Hibernate (to Disk): echo "disk" > /sys/power/state

Refere to System Power Management State


Using dav://host.local gives error message "Connection refused"

I had a similar issue: I enabled file sharing in Gnome on host A and the shared folder from host A was automatically discovered by host B on the same network, but it was not possible to access its content due to a connection error. Such error usually means there is a firewall blocking the destination port and that turned out to be the case. However the port number was different from the expected HTTP/S ports (80/443). I ran netstat -tpan and found an instance of httpd listening on port 43995. After enabling this port on host A's firewall I was able to mount the share on host B and access its content.


Vulkan VK_ERROR_INITIALIZATION_FAILED (18.04, Radeon HD 6520G)

The wikipedia page for AMD GPUs clearly lists Terascale 2 as NOT supporting vulkan.
The ammount of rebranding and renming of graphics components makes this quite the hunt.

For those in similar "does my AMD card support vulkan?" waters:

1.) identify your card from the commandline

$lspci |grep 'VGA'

2.) Search the GPU specs at a site such as notebookcheck.net and find its 'architecture' or 'chipset'

3.) look up the chipset on the  wikipedia page for AMD GPUs


How do I update PHP version, 7.2.24-0ubuntu0.18.04.6 to latest version?

You have 3 different options (in order of least to most effort):

As you're running a Canonical/Ubuntu supported version of PHP, you're guaranteed at least 5 years of support (and thus security patches) from Canonical, regardless of the PHP project's policy.  You can literally do nothing yet still have a supported version of PHP until 2023.
Many people install the ondrej PHP PPA and install PHP from there.  I do not have an opinion over this particular PPA but I have had to help others debug problems caused indirectly by the PPA.
Upgrade to Ubuntu 20.04.1 which bumps PHP to v7.4.


Cannot boot Windows 7 after install Ubuntu 14.04

Are you sure you didn't accidentally format the Windows 7 partition? Cause If Ubuntu, during the installation, didn't recognize the Windows 7 partition, so it doesn't exist.

  => Windows 7/8/2012 is installed in the MBR of /dev/sda.

Above partition could refer to System Reserved by windows and it is 100 MB parition.

So access to your Ubuntu, open GParted application:

if you see one partition for windows 7 so you need to reinstall it.
if you see two partitions and you can see the folders of
your windows 7 (Windows/Program files/Document and Settings ...
etc), so you need to do boot-repair


Skype not working after upgrading to 13.04 from 12.10

This should work: source: LinuxG.net

Open the /etc/ld.so.conf.d/skype.conf file, in your favourite text editor, as root:

$ gksudo gedit /etc/ld.so.conf.d/skype.conf

Paste the following line:

/usr/lib/i386-linux-gnu/mesa/

Run ldconfig:

$ sudo ldconfig -v

This is it. Enjoy.


Fresh Ubuntu on SSD dual mode with Win 10 is extremely SLOW

I found a similar question here and the first answer solved my problem.
To be more exact I did the following and it solved my issue:

  sudo nano /etc/default/grub
  Then add the kernel boot parameter: video=SVIDEO-1:d, so it will look like this: >GRUB_CMDLINE_LINUX_DEFAULT="quiet splash video=SVIDEO-1:d"
  sudo update-grub
  sudo reboot

NOTE: The above solution is copied from this page and it is suggested by Jan Dostrasil.


What is the "right" way to debianize software that uses the scons build-system?

The debian/rules file is a Makefile. Anything you might want to do in a "fake" Makefile, you can just do there. The dh command  is a helper that will run most build systems with Debian defaults for you. I believe it supports scons If so, all you need is:

#!/usr/bin/make -f

%:
    dh $@

You can override its default behavior if you need to pass custom options (or if it doesn't really support scons). Then your rules file might look like:

#!/usr/bin/make -f

SCONS=scons

%:
    dh $@

override_dh_auto_build:
    $(SCONS) --prefix=$(DEB_DESTDIR)/usr

override_dh_auto_clean:
    dh_auto_clean
    $(SCONS)  -c

override_dh_auto_install:
    $(SCONS) install --prefix=$(DEB_DESTDIR)/usr

Sometimes, the best way to learn how to do something is to look at how other packages do it. The command:

reverse-depends -b scons

will list all packages that Build-Depend on scons Grab their source and see the different ways they build.


My computer doesn't recognize the following library: linux/config.h when compiling

As the link below explains, somewhere in the 2.6.19 kernel, linux/config.h was removed.

http://www.linuxquestions.org/questions/linux-kernel-70/removal-of-include-linux-config-h-file-in-2-6-19-kernel-506363/


Is it possible to make a folder/partition of RAM and sync it with persistent storage automatically, periodically?

Create a RAM disk

As described here you can make a RAM disk

mkdir -p /media/nameme
mount -t tmpfs -o size=2048M tmpfs /media/nameme/

Copy last backup into RAM disk

cp -ru /source/path /destination/path

Where source/path is the location of the backup-data, and /destination/path is the RAM disk location

  Note: The same script which runs on boot and execute Create a RAM
  disk can also copy the data from the backup-folder into the RAM disk.

auto save periodically the data on persistent storage:

You can create a simple script which will copy the content of this RAM disk once a period of time (minute/hour/etc) using a cron tab
See here how to set a cron-tab.

crontab -e

running a copy/backup command every 15 minutes:

*/15 * * * * /path/to/command

Copy command:

The command might be something like:

cp -ru /source/path /destination/path

  -r -recursive

  -u --update - copy only when the SOURCE file is newer than the destination file or when the destination file is missing


vsftp: don't allow ftp user to move up in a directory tree

According to this answer, you need to edit /etc/vsftpd.conf and ensure the following line is there:

chroot_local_user=YES


Does Enigmail defaultly check keyservers upon receiving signed emails?

The key is (usually) written into the message headers. But this (encrypted) mail does not contain any information on the sender, if it isn't signed. Let's analyze what is contained in an OpenPGP messages.

Decomposing an Encrypted OpenPGP Message

You can see this if you list the packets contained in an encrypted message:

$ echo foo | gpg --encrypt --recipient 0xa4ff2279 | gpg --list-packets

The output starts with the "publicly" visible, unencrypted headers, which contain the subkey the message is encrypted for:

:pubkey enc packet: version 3, algo 1, keyid CC73B287A4388025
    data: [4092 bits]

After entering the passphrase, GnuPG will also print the remaining packets:

:encrypted data packet:
    length: 63
    mdc_method: 2
gpg: encrypted with 4096-bit RSA key, ID A4388025, created 2014-03-26
      "Jens Erat (born 1988-01-19 in Stuttgart, Germany)"
:compressed packet: algo=2
:literal data packet:
    mode b (62), created 1402861918, name="",
    raw data: 4 bytes

Decomposing a Signed OpenPGP Message

A signed message contains the signing (sub)key ID of the sender, see the :signature packet line (fourth packet).

$ echo foo | gpg --sign | gpg --list-packets

(GnuPG asks for password, for signing)

:compressed packet: algo=1
:onepass_sig packet: keyid 8E78E44DFB1B55E9
    version 3, sigclass 0x00, digest 2, pubkey 1, last=1
:literal data packet:
    mode b (62), created 1402862406, name="",
    raw data: 4 bytes
:signature packet: algo 1, keyid 8E78E44DFB1B55E9
    version 4, created 1402862406, md5len 0, sigclass 0x00
    digest algo 2, begin of digest 9a d2
    hashed subpkt 2 len 4 (sig created 2014-06-15)
    subpkt 16 len 8 (issuer key ID 8E78E44DFB1B55E9)
    data: [4095 bits]

An encrypted OpenPGP message could of course also be signed. I'm leaving composing the commands for verifying this as exercise to the interested reader.

Obtaining the Public Keys

Using the key ID obtained from the signed message, one can fetch the key from the key servers. Most mail clients (plugins) will do this automatically for you:

$ gpg --recv-keys 0x8E78E44DFB1B55E9
gpg: requesting key FB1B55E9 from hkp server pool.sks-keyservers.net
gpg: key A4FF2279: "Jens Erat (born 1988-01-19 in Stuttgart, Germany)" not changed
gpg: Total number processed: 1
gpg:              unchanged: 1

If the message isn't signed, you (or your OpenPGP client) might search the key servers for the mail address of the other. Result is the same, you still cannot be sure about the validity of that key.


How to disable wakeup by bluetooth mouse?

I found a solution.
echo XHC > /proc/acpi/wakeup

fixes the problem, but it doesn't survive reboots.
This command should be setup in systemd as a oneshot service.


Tool for enumerating list indices in libreoffice writer

Libreoffice Writer is an extremely powerfull tool. Getting to know the tools you need takes a bit of learning. Take a look at fields, and in particular Variables ("Number range") to insert numbers that automatically update if a field of the same type is inserted later.


sed: Insert a string containing path delimeters

Use

sed -i '13i\/home/me/dostuff.py &' /etc/rc.local

to insert it (i.e. place it before line 13); or

sed -i '13a\/home/me/dostuff.py &' /etc/rc.local

to append it (i.e. place it after the current line 13).

Note that forward slashes aren't special in sed's i and a commands - only in regular expression matches such as /pattern/d or s/pattern/replacement/ (although even there, they may be replaced by other delimiters such as \%pattern%d or s#pattern#replacement# - at least in GNU sed).


What is the meaning of p3p1, p2p1, p1p1 network device?

This is a network interfaces, and it is derived from:

Lan-On-Motherboard interfaces: em<port number> (ethernet-on-motherboard <1,2 ..>)

PCI add-in interfaces: p<slot number>p<port number>_<virtual function instance>


Some images appear discoloured in Firefox

Solved - the issue was the same as this one on the Firefox Forums.

That can be caused by a problem with the color profile for your display monitor or color profiles embedded in images.
You can disable color management to test that.
You can set the pref gfx.color_management.mode to 0 on the about:config page to disable Color Management.
You need to close and restart Firefox to make the change effective.
See:

http://kb.mozillazine.org/gfx.color_management.mode


booting directly in windows 8.1 after instaling ubuntu 12.04 lts

Use the Windows "bcdedit" command http://technet.microsoft.com/en-us/library/cc709667(v=ws.10).aspx to re-enable GRUB as your primary boot loader, or install rEFInd http://www.rodsbooks.com/refind/ to manage the boot process. More detail on where GRUB2 goes in the process may be had at http://apcmag.com/how-to-dual-boot-windows-8-and-linux.htm


Unity Launcher integration and quickly run... fail

I don't know why but now, after I've copied the file myproject.desktop.in (myproject is the name of the quickly project) inside the project folder in ~/.local/share/applications/myproject.desktop, it works.


How to install Teamviz in Ubuntu 16.04 64 bit?

Download and install the next packages. For installing use the command:

sudo dpkg -i PACKAGE_NAME.deb

Download and install these packages

libgcrypt11
libgnutls26
libtasn1-3

Download and install the latest version of Teamviz Pomodoro from http://www.teamviz.com/downloads/


Global keybindings to commands or shell scripts in i3

I found an answer for fixing the audio problem at How to manage audio with i3?


What's the download size of the ubuntu-restricted-extras package?

It is only 6.8mb in size so very small it is just some codecs for music and video and flash player.


The Ubuntu Security Team maintains a database of CVEs and their patches.

You can see for yourself if the patch for a particular CVE has been pushed: https://people.canonical.com/~ubuntu-security/cve/2018/CVE-2018-10933.html

Ubuntu's Debian (not Snap) repositories use a snapshot method. After release, most packages WON'T receive new upstream versions but WILL receive security patches and high-priority bugfixes. This may be different behavior than the upstream website leads you to believe.

Example: libssh 0.6.3-4.3 is in the Ubuntu 16.04 repos. Ubuntu WON'T update the package to 0.7.6. Ubuntu WILL patch the vuln, and update the package to (something like) '0.6.3-4.3Ubuntu0'

EDIT: I was close. They did update the version to 0.6.3-4.3ubuntu0.1

Snaps, of course, work differently.


Can't boot Ubuntu 12.04 from external Hard Drive using Mac

First of all your drive needs to be formatted with the GUID partition table (changed by clicking the options button when partitioning in Disk Utility),

Why because Intel Macs can only boot from GUID hard drives. Second you should be able to boot using rEFIt, but rEFIt must be installed on a External drive E.G. CD, USB etc, and not on the internal Hard Drive as rEFIt supports booting from ext formatted hard drives


Ubuntu can be installed to the HDD. Instead of creating a partition, leave it unallocated since ubuntu will need to make 2 partitions (swap and root). Then, choose the option to use freespace.
 You could also choose the something else option and make the partitions from the installer if you want to manually partition.

Note: you need Basic partitioning. Ubuntu does not know what to do with Windows dynamic partitions.


Is there an option to "force" the dash to open a file after I click on it instead of going to options?

In 14.04, if you double-click the file in the Files & Folders lens then it seems to open straight away (using the default application), without going through the drop-down.  Does that help?


Run the following command nvidia-settings (This will only work if you are using Nvidia proprietary driver). A GUI will pop-up. Click X Server Display Configuration. Once you select it, click Save to X Configuration File

Open your terminal and run this as root:
nano /etc/X11/xorg.conf

Add { ForceCompositionPipeline = On } to the "Screen" Section in the "metamodes" Option:

Option         "metamodes" "DP-0: nvidia-auto-select +2560+0 { ForceCompositionPipeline = On }, DP-2: nvidia-auto-select +0+0 { ForceCompositionPipeline = On }"

I have two monitors, both connected to Display Port (DP). So I added it to DP-0 and DP-2. Adjust appropriately based on your setup.


docker-ce post installation configuration failure on Ubuntu 20.04

Do you have a VPN running in the background while installing docker?
Apparently, tunneling your network [while installing docker leads to problems][1]. It just happened to me as well. Turned off openvpn via

sudo service openvpn stop

and docker installed beautifully.


How to add multiple directories to Xscreensaver?

Not really an answer to your question, but after configuring one directory (running xscrennsaver-demo, no need to edit manually .xscreensaver), you can create symbolic links (with ln -s) to all other images in other directories you would like to be read by the screensaver.


YouTube webapp crashed after upgrade to 13.10

After you uninstalled unity-webapps-youtube youhave to remove manually YouTubeyoutubecom.desktop from this directories: ~/.local/share/applications/ and /usr/share/applications. To do this you can use the following commands:

rm /home/radu/.local/share/applications/YouTubeyoutubecom.desktop
sudo rm /usr/share/applications/YouTubeyoutubecom.desktop

After this, YouTube webapp will not appear anymore in Dash (even if unity-webapps-youtube is installed).


I want to know what config options were used to compile apache?

apache2 -V  Print the version and build parameters of apache2, and then exit. (source)


Touchpad Fujitsu UH-X is not detected in Ubuntu 20.04

That's what worked for me.

Load Terminal with Ctrl-Alt-T
sudo apt install xserver-xorg-input-synaptics
sudo reboot
sudo modprobe i2c_hid

It started working right after 4), not sure if steps 2 and 3 were even necessary. Also I have to run 4) every time I log in, adding it to start-up scripts doesn't work for some reason


Reading/Writing To Serial Port Not Working

You are missing the loop-back connection/jumper. The serial port send data through pin 3 and receive them through pin 2.

As you are using same port, connect 2 ↔ 3 with a wire.

Reference: Wikipedia: Loopback


First - formatting a large drive with ext2 was a very definite mistake.  So let's fix that.

Open Disk Utility from the Dash.  You will see a list of all your Storage Devices on the left.  Select the new hard drive, and click Format Drive.  Select the Scheme GUID Partition Table, and click Format.

Now, click Create Partition under Volumes.  Make sure the Type is set to Ext4, and give it a better name than New Volume.  Make sure Take ownership of filesystem is checked, and finally click Create.

Now, click Mount Volume - you'll see a Mount Point of /media/nameyoupicked, and in the File Manager, it will show up as a mounted Device.

The new device won't automatically be mounted when you reboot, but it will still show up in File Manager and will mount automatically if you click it.

If that's not sufficient for you - if you need the disk to automatically be mounted at each boot, before you even log in - that can be done as well, but please ask it as a separate question. :)  Hope this helped!


list of all mac address i've connected to in the past

Whatever access point you connect to with Network Manager , will have a settings file in /etc/NetworkManager/system-connections folder. For instance:

$ sudo grep -i 'mac' /etc/NetworkManager/system-connections/Jes
[sudo] password for xieerqi:
mac-address=**:**:**:**:**:** # obfuscated for reasons

If you were using something other than Network Manager - bad news, it's not possible to recover that information


Nautilus click on mounted partition opens LibreOffice

The cause of the problem seems to be some confused permissions.

The /Home directory pre-dated the installation, and as I wasn't the initial user (UID=1000) I switched UIDs after installation.

Whether because of that or some other reason I noticed that I needed to use sudo to list /media/USER, and directories weren't listed in colour.

I added USER to the USER group as it was missing, and

  sudo setfacl -m u:USER:r-x /media/USER

seems to have corrected the permissions.

I'm now able to view the mounted drives in Nautilus,


If It shall be possible with encrypted messages, must sender and the receiver be able to read encrypted messages.

sudo apt-get install gpgv2

A suggestion with GPG

Instead of typing text directly into a message, you can write text to a file that you can then use GPG for encryption.

(For use of my suggestion, there is no need of GPG keys.)

An example of that approach:

Create a file on your desktop called message_enc.txt.
Open the terminal.
Type gpg --symmetric message_enc.txt
Choose password. The one who wants to decrypt the message_enc.txt file later should enter the same password to decrypt it.

Result:
The file that is now encrypted have about the same name as before, the only difference  that there is a new extension at the end of the filename (usually .gpg).

To send the encrypted file in Thunderbird:

Open Thunderbird.
Send a message to someone, instead of writing something in the message you should attach the encrypted file.

To decrypt the message:

Open the terminal.
Type gpg --decrypt message_enc.txt.gpg > message.txt

Update 2016-12-21:
It's possible to use the Thunderbird add-on Enigmail to encrypt and read encrypted e-mails.


How to create a video from a series of images

You can use the -framerate option of ffmpeg to control this. It's possible to use a fractional value for this setting. Using -framerate 1/5 will show all frames for 5 seconds, -framerate 1/4 will show them for 4 seconds.

I you require varying duration for each frame, it is necessary to alter the overall framerate, and duplicate these frames. You could set the framerate to 1, which would be 1 second increments, then have a number of copies of each frame which matches the desired duration in seconds. It may be possible to use soft-links rather than full copies of files to avoid using excessive disk space.


Is there a way to install ubuntu by copying files to the disk?

It is not possible to do it the way you have tried and, no, it won't work to just copy files from a computer to a USB stick and make it work. There is a way to install Ubuntu (or whichever distribution you choose) but it is tricky. There is a recipe in the accepted answer on:
How to Create a Full Install of Ubuntu 20.04 to USB Device Step by Step
Be sure to follow it to the letter.


install vagrant ( homestead 2.0 ) without virtualization enabled

I'm also using vagrant on one of my computer that doesn't support hardware level visualization. So, In that PC, I'm not able to run any 64bit guest OS. I only able to use 32bit OS as guest. I believe the case will be the same for you here. Please have a look on it.

If you're interested on setting up a development environment (LAMP) on a new ubuntu machine, then please read my guide 'A developer guide to setting up Ubuntu for web development'. In that I've described how to setup a LAMP and MEAN stacks on virtual environments in ubuntu using vagrant. May be you could use it to get a homestead running environment.


Solved by removing event23(in my case); "sudo rm /dev/input/event23"


Which driver to fully support GeForce GT 750M and have QHD resolution working?

To add a missing resolution, first calculate the VESA Coordinated Video Timing mode using cvt like so:

$ cvt 2560 1440
# 2560x1440 59.96 Hz (CVT 3.69M9) hsync: 89.52 kHz; pclk: 312.25 MHz
Modeline "2560x1440_60.00"  312.25  2560 2752 3024 3488  1440 1443 1448 1493 -hsync +vsync

Then register this new mode using the calculated modeline, I use qhd as a name here:

xrandr --newmode qhd 312.25  2560 2752 3024 3488  1440 1443 1448 1493 -hsync +vsync

According to your xrandr output the screen for which you want to add the resolution is eDP-1-1, so now add the mode to this output using:

xrandr --addmode eDP-1-1 qhd

Now the resolution should be available in GUI tools and can be chosen there. To set it with xrandr do:

xrandr --output eDP-1-1 --mode qhd


how to automatically reset ubuntu after rebooting computer

What you are looking for is Lethe, a deep freeze like software for Ubuntu.

You can download Leethe from this link.

Then follow the steps from here.


Open System Settings from the launchbar and click 'Keyboard' then 'Shortcuts' then 'Windows'

You can assign alt+tab there as a windows switcher.


How do you use right alt as your input switch?

This is what the GNOME docs (which are also available on your desktop offline) says about setting keyboard shortcuts:

https://help.gnome.org/users/gnome-help/stable/keyboard-shortcuts-set.html

I think that applies to Ubuntu GNOME as well, even if I'm not sure.


How do I change back to my X-session (GUI) tty?

Your graphical session is usually located at either Ctrl+Alt+F7 or Ctrl+Alt+F8. For me, running Ubuntu 13.04 it is F7.

A related, interesting read: What does "Ctrl + Alt + F12" do?


Can not get to login screen, background starts with terminal prompt only

He can try to reinstall unity as part of the ubuntu desktop, with these commands:

sudo apt-get update
sudo apt-get install --reinstall ubuntu-desktop
sudo apt-get install unity

Then restart and wait...

(If he is not logged in to his user account, he'll need to do that first.)


Paste output stream to the current writing place

You can use xclip or xsel to manipulate the clipboard from the command line. To paste, there is no other option than to issue a paste command in the application. There, you can use a bash tool such as xdotool or xvkbd to send a hotkey combination to the application, typically Ctrl+v.
Following two lines (not counting the shebang) will load a text file to the clip board and send a Ctrl+v to paste:
#!/bin/bash
xsel -bi < /home/user/Documents/filename.txt
xdotool key Control+v


How to create a DATA partition accessible by multiple users and multiple linux OS?

Right now I have created an ext4 partition but I have problems with multiple users, because every time that I change something from the 1 user, then I need to change the permissions again, which makes the whole purpose fail.

I got 1 word for you: groups

permissions can be set for one user; example /home/$USER/
permissions can be set for a group of users; that would/could be a datadirectory.

So ...

Create a group "allusers": sudo groupadd allusers
Add user rinzwind to that group: sudo usermod -a -G allusers rinzwind
Create a partition, give it a mountpoint (let's call it "discworld");
Change the group of the mountpoint to a group;

chgrp-R allusers /discworld/

A user added after this you will need to add to the group for that user to gain access.

For new files to get the group set on creation:

Use grpid on the mount.
or use sudo setfacl -Rdm g:allusers:rx /discworld/ to use the ACL method (getfacl /discword to list permissions).

If you want a really fancy setup:

/discworld/user1/
/discworld/user2/
/discworld/user3/
/discworld/user4/
/discworld/user5/
/discworld/common/

set these to owner user{1-5} and group user{1-5} and users can use this as private data.
set common to group "allusers" and add user{1-5} to group "allusers".
you can use a "filesystem quota" on the user or on the group to limit the amount of data.

  I am thinking of using ntfs filesystem for the DATA partition which can be given permission rights during mount,

Only use NTFS when you also have a Windows; otherwise you can get in trouble when it does not mount due to errors. It might be fixable, it might not. Just don't take the risk.

Basically the same method: mount the partition with group "allusers". You can add a gid=allusers,umask=0022 to the mount options.


How To Launch GUI App With Upstart Script

Upstart is primarily for managing system services.  If you want to run an application as part of the user session, there are better tools.

Via the GUI

You can configure a startup application in a user's session by picking Startup Applications... from the cog menu in the top right of the screen, and then pick Add and fill in the details for gedit.

When you log in next time, the application should start with the session.

Manually

If you can't use the UI to configure this, it is possible to configure it by dropping a .desktop file in one of the autostart directories according to the Autostart specification:

http://standards.freedesktop.org/autostart-spec/autostart-spec-latest.html

If you want it to affect every user on the system, place the file in /etc/xdg/autostart.  If you only want to affect a single user, place the file in ~/.config/autostart.

The .desktop file should look something like:

[Desktop Entry]
Type=Application
Exec=/usr/bin/gedit
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
Name=GEdit
Comment=

If you place the file in the user's home directory, make sure you set the execute bit on the file.  This is part of a security measure to stop programs unintentionally writing working .desktop files due to bugs.


mysql: Access denied for user 'root'@'localhost' (using password: NO)

using password: NO tells you what is wrong. You probably have a password set for the user root --> You need to enter a password.

You can let mysql prompt for a password running:

mysql --password

or shorther:

mysql -p

If you need to connect with user root run

mysql --user=root -p


Make sure it will not go beyond the 4 primary partitions; if so then your PC will not boot up.
You can make extra partition with GParted--up to four primary partitions, or up to three primary partitions plus an extended partition that acts as a contained for logical partitions. This way you can effectively have more than four partitions.
Make sure you have sufficient space for Windows 8.
Install Windows 8.
Now you notice that only Windows 7 and 8 are listed in Windows's boot loader.
You have 2 option to make it so you can select Ubuntu when booting your machine:

Add Ubuntu in windows boot loader by using easyBCD.
Reinstall GRUB 2 by live CD.

For this watch this video.

After this if your windows in not listed in grub 2 then type

sudo update-grub2

Even if Windows is not listed retry after mounting your windows drive.

Here is a video for updating GRUB2.


Setting up Gmail and Thunderbird in 11.10

Are you able to connect to the Internet and access web sites using Firefox?

If yes, system proxy settings should work.

If you need an authentication for proxy server, try with Manual Proxy settings Radio button and give the proxy server and port details.

You can get this information from Firefox → Preferences → Advanced → Network.

Now when Thunderbird starts again, it may ask for proxy authentication and you can give your username and password for proxy server.


iPython3 opened in Terminal - os.path.dir adds letter 'd' to path and triggers File not found error

os.listdir returns a list of file names. With the

for file in filename

loop you are iterating over the letters in this file names, and the first file name found seems to start with a 'd'. Remove this loop.

Later in your code

print(len(f))

will throw an exception as you can't use len with a file handle. If you want to get the size of the file use os.path.getsize()