The prefork model imposes quite a few restrictions on HTTP even without HTTP/2, but with HTTP/2, it prevents many features of HTTP/2 being used.  Since each request occurs in a separate process and there is no multi-threading, Apache isn't able to multiplex them (serve multiple requests on the same TCP connection) unless it changed the way prefork works quite substantially, which it has chosen not to.  So HTTP/2 support is limited to a single request at a time per connection when using prefork.

(This is documented here)

A good modern way of integrating PHP with a web server is to use PHP-FPM (PHP's built-in FastCGI process manager) and having the web server relay PHP requests off to that, and receive their responses.  Then you can use a multithreaded web server like Apache with the worker MPM, or an event-based web server like Apache with the event MPM, or nginx (which is particularly good at HTTP/2, due to its ability to hold open thousands of connections with very little memory).  In fact this is probably the most common way of using PHP with nginx, and I've also seen it used on Apache2 before for security reasons (eg having different PHP apps running as separate users).  Supporting HTTP/2 seems like a decent reason too.

There are many guides to setting up web servers and PHP to use PHP-FPM.


How do I deploy an OpenStack cloud with Juju?

Installing OpenStack

If you want to get up and running quickly go here instead:

How do I install OpenStack?

This answer is a more detailed look at how to use Juju with OpenStack.

Scope

The OpenStack platform is powerful and its uses diverse. This section of
documentation is primarily concerned with deploying a "standard" running
OpenStack system using, but not limited to, Canonical components such as MAAS,
Juju and Ubuntu. Where appropriate other methods and software will be mentioned.

Assumptions

Use of MAAS - follow these intructions first.
Use of Juju
Local network configuration - This document assumes that you have an adequate local network configuration, including separate interfaces for access to the OpenStack cloud. Ideal networks are laid out in the [MAAS][MAAS documentation for OpenStack].

Planning an installation

Before deploying any services, it is very useful to take stock of the resources
available and how they are to be used. OpenStack comprises of a number of
interrelated services (Nova, Swift, etc) which each have differing demands in
terms of hosts. For example, the Swift service, which provides object storage,
has a different requirement than the Nova service, which provides compute
resources.

The minimum requirements for each service and recommendations are laid out in
the official OpenStack Operations Guide

The recommended composition of nodes for deploying OpenStack with MAAS and Juju
is that all nodes in the system should be capable of running ANY of the
services. This is best practice for the robustness of the system, as since any
physical node should fail, another can be repurposed to take its place.
This obviously extends to any hardware requirements such as extra network interfaces.

If for reasons of economy or otherwise you choose to use different
configurations of hardware, you should note that your ability to overcome
hardware failure will be reduced. It will also be necessary to target
deployments to specific nodes - see the section in the MAAS documentation on tags.

Create the OpenStack configuration file

We will be using Juju charms to deploy the component parts of OpenStack. Each
charm encapsulates everything required to set up a particular service. However,
the individual services have many configuration options, some of which we will
want to change.

To make this task easier and more reproduceable, we will create a separate
configuration file with the relevant options for all the services. This is
written in a standard YAML format
(see www.yaml.org if this is unfamiliar to you).

Here is an example of an openstack-config.yaml:

keystone:
  admin-password: openstack
  debug: 'true'
  log-level: DEBUG
nova-cloud-controller:
  network-manager: 'Neutron'
  quantum-security-groups: 'yes'
  neutron-external-network: Public_Network
nova-compute:
  enable-live-migration: 'True'
  migration-auth-type: "none"
  virt-type: kvm
  #virt-type: lxc
  enable-resize: 'True'
quantum-gateway:
  ext-port: 'eth1'
  plugin: ovs
glance:
  ceph-osd-replication-count: 3
cinder:
  block-device: None
  ceph-osd-replication-count: 3
  overwrite: "true"
  glance-api-version: 2
ceph:
  fsid: a51ce9ea-35cd-4639-9b5e-668625d3c1d8
  monitor-secret: AQCk5+dR6NRDMRAAKUd3B8SdAD7jLJ5nbzxXXA==
  osd-devices: /dev/sdb
  osd-reformat: 'True'

For all services, we can configure the openstack-origin to point to an install source. In this case, we will rely on the default, which will point to the relevant sources for the Ubuntu 14.04 LTS Trusty release. Further configuration for each service is explained in this document.

Other configurations

Other settings and configuration options are possible for deployment of the OpenStack services. These are detailed in the documentation of the individual charms used by Juju, and can be inspected by visiting the online Juju Charm Store and searching for the charm using the search box in the top left-hand-side of the page. the configuration settings are then detailed under "Configuration" in the main page, as shown:

Deploying OpenStack with Juju

Now that the configuration is defined, we can use Juju to deploy and relate the services.

Initialising Juju

Juju requires a minimal amount of setup. Here we assume it has already been configured to work with your MAAS cluster (see the [Juju Install Guide][juju_install] for more information on this.

Firstly, we need to fetch images and tools that Juju will use:

juju sync-tools --debug

Then we can create the bootstrap instance:

juju bootstrap --upload-tools --debug

We use the upload-tools switch to use the local versions of the tools which we
just fetched. The debug switch will give verbose output which can be useful.
This process may take a few minutes, as Juju is creating an instance and
installing the tools. When it has finished, you can check the status of the
system with the command:

juju status

This should return something like:

environment: maas
machines:
  "0":
    agent-state: started
    agent-version: 1.18.1.1
    dns-name: localhost
    instance-id: localhost
    series: trusty

Deploy the OpenStack Charms

Now that the Juju bootstrap node is up and running we can deploy the services
required to make our OpenStack installation. To configure these services
properly as they are deployed, we will make use of the configuration file we
defined earlier, by passing it along with the --config switch with each deploy
command. Substitute in the name and path of your config file if different.

It is useful but not essential to deploy the services in the order below. It is
also highly reccommended to open an additional terminal window and run the
command juju debug-log. This will output the logs of all the services as they
run, and can be useful for troubleshooting.

It is also recommended to run a juju status command periodically, to check
that each service has been installed and is running properly. Juju will
automatically try to fetch the best possible version of the
charm from online Charm Store. If you are installing from within a restricted or
closed network, it is possible to pre-fetch the required charms.
See [the documentation for offline charms][charms-offline].

juju deploy --to=0 juju-gui
juju deploy rabbitmq-server
juju deploy mysql
juju deploy --config openstack-config.yaml openstack-dashboard
juju deploy --config openstack-config.yaml keystone
juju deploy --config openstack-config.yaml ceph -n 3
juju deploy --config openstack-config.yaml nova-compute -n 3
juju deploy --config openstack-config.yaml quantum-gateway
juju deploy --config openstack-config.yaml cinder
juju deploy --config openstack-config.yaml nova-cloud-controller
juju deploy --config openstack-config.yaml glance
juju deploy --config openstack-config.yaml ceph-radosgw

Add relations between the OpenStack services

Although the services are now deployed, they are not yet connected together.
Each service currently exists in isolation. We use the juju add-relation
command to make them aware of each other and set up any relevant connections
and protocols. This extra configuration is taken care of by the individual
charms themselves.

We should start adding relations between charms by setting up the Keystone authorization service and its database, as this will be needed by many of the other connections:

juju add-relation keystone mysql

We wait until the relation is set. After it finishes check it with juju status:

juju status mysql
juju status keystone

It can take a few moments for this service to settle. Although it is certainly possible to continue adding relations (Juju manages a queue for pending actions) it can be counterproductive in terms of the overall time taken, as many of the relations refer to the same services.

The following relations also need to be made:

juju add-relation nova-cloud-controller mysql
juju add-relation nova-cloud-controller rabbitmq-server
juju add-relation nova-cloud-controller glance
juju add-relation nova-cloud-controller keystone
juju add-relation nova-compute mysql
juju add-relation nova-compute rabbitmq-server
juju add-relation nova-compute glance
juju add-relation nova-compute nova-cloud-controller
juju add-relation glance mysql
juju add-relation glance keystone
juju add-relation cinder keystone
juju add-relation cinder mysql
juju add-relation cinder rabbitmq-server
juju add-relation cinder nova-cloud-controller
juju add-relation openstack-dashboard keystone
juju add-relation swift-proxy swift-storage
juju add-relation swift-proxy keystone

Finally, the output of juju status should show the all the relations as complete. The OpenStack cloud is now running, but it needs to be populated with some additional components before it is ready for use.


How do I install a .bin archive on Ubuntu 16.04?

Please visit:

https://docs.genymotion.com/Content/01_Get_Started/Installation.htm

and it'll give you all the details about how to install. Also know that it needs Oracle VirtualBox and DKMS to operate.


Completely remove user while using chroot from Ubuntu RPi image

Okay, I found out.
The answer is file /etc/cloud/cloud.cfg there you can configure default user/groups/etc.
Best


execute-command; limit program cpu usage for executable program

Read man bash, and look for the ulimit section that starts with:

   ulimit [-HSTabcdefilmnpqrstuvx [limit]]
          Provides  control over the resources available to the shell and to processes started by it, on systems that allow such control.

Also read man nice:

NAME
   nice - run a program with modified scheduling priority


How do I let my client to use internet via using iptables in Ubuntu 16.04 in VirtualBox

Assuming:
enp0s3 is on the 192.168.1.0/24 sub-net, which in turn goes to internet.
enp0s8 is on the 10.10.10.0/24 sub-net, at 10.10.10.11 and is local.
10.10.10.1 doesn't actually exist.
The client is somewhere in the 10.10.10.40 - 10.10.10.60 pool.

Then your basic router type iptables rule needs to be:
sudo iptables -t nat -A POSTROUTING -o enp0s3 -j MASQUERADE

And your options router statement needs to be:
option routers 10.10.10.11;

EDIT: based on your other question, your client might be outside of your dynamic address pool, getting its IP address of 10.10.10.10 based on MAC (Machine Address Code). Such is fine, but it's lease will not appear in the /var/lib/dhcp/dhcpd.leases file.


The ubuntu machine do not get restart using reboot command

If it is a remote machine that you are rebooting, you will have to establish the remote connection again as it will get disconnected during the rebooting process.


How to use ubuntu 13.04 with ATI RV635 [Mobility Radeon HD 3650] graphics card?

Makarewicz' PPA downgrades xorg to 1.12? I imagine it must downgrade a bunch of dependencies as well, and I'm sure it becomes more difficult with each Ubuntu release. Unixmen recommended installing a legacy Catalyst driver without downgrading xorg, though they also recommend Makarewicz' PPA. Something's not right here, but that lighter touch seems more likely to work as continued Ubuntu releases move farther away from no longer supported hardware. Unixmen's lighter touch can be found here. I don't have an affected Radeon card so I can't vouch for any of this.


Your free -h shows...

              total        used        free      shared  buff/cache   available
Mem:            15G        9,9G        266M        4,7G        5,4G        508M
Swap:           30G        3,2G         27G

indicates that you have enough RAM and SWAP (you ARE using hibernation).

Tuning your system with regards to swap is a tricky procedure.

It involves:

how much RAM you have
how much SWAP you have
whether swap if FILE based or PARTITION based
what applications you run and how much RAM they use
whether you use hiberation, or not

Setting up appropriate swap space is open for large debate. GENERALLY speaking, swap space should be 50-120% of total RAM. Larger amounts of swap are used in a hibernation configuration.

Assuming that you have enough RAM and swap, vm.swappiness is a parameter that you can adjust to optimize the use of RAM vs swap. To see your current setting:

sudo sysctl vm.swappiness

it's normally set to 60.

To temporarily change this setting:

sudo sysctl vm.swappiness=nn

where nn=0 to 100.

Lower settings make more use of RAM and less swapping. Higher settings reduce RAM use and increase swapping.

After determining the optimum value for your configuration, to set it permanently, edit /etc/sysctl.conf. Add this value to the bottom of the file:

vm.swappiness=90

we've determined that 90 is a good value for your use. This setting MAY slow down your system a bit, as swapping is based on slow disk I/O.

then reboot.


Reallocate partition space from /boot to /

Warning This will take some time, so start this before going to bed. ;)

Warning If there is a power failure during this operation you will loose all of your data, so do a full system backup before starting.

Download, burn and boot the gparted live CD
Shrink /dev/sda5 to 1GByte
Move /dev/sda6 to the left next to /dev/sda5
Extend /dev/sda6 to the end of the hard drive
Apply changes
Go to bed.


Cannot launch Thunar after upgrading to 20.04

I downloaded and installed libxfconf-0-2_4.12.1-1_amd64.deb and am now able to open Thunar again. I do not know if this is the proper fix long-term, but it works for now.


Script to Automatically change wallpaper when charging

You do it in three steps. First, you need to create an udev rule. I use my mouse as an example.
/etc/udev/rules.d/99-battery.rules:
ACTION=="change", \
KERNEL=="hidpp_battery_0", \
SUBSYSTEM=="power_supply", \
ATTR{model_name}=="Performance MX", \
TAG+="systemd", \
ENV{SYSTEMD_READY}="1", \
ENV{SYSTEMD_USER_WANTS}="battery@%E{POWER_SUPPLY_STATUS}.service"

If you make any changes to your udev rule and the device is already connected, then you must explicitly apply your rule again with udevadm trigger.
The easiest way to find useful attributes for your device is to start an udev monitor, connect your charging cable. Now you should see the udev path and environment attributes.
$ udevadm monitor --udev --environment

With your udev path, you can query your device for the rest of the attributes (in my case):
$ udevadm info -a --path='/sys/devices/pci0000:00/0000:00:13.1/usb6/6-3/6-3:1.2/0003:046D:C52B.0006/0003:046D:101A.0007/power_supply/hidpp_battery_0'

Next, you need to create a systemd template. Such a service is called an "instantiated" service. It makes it possible to send a single argument via the service name. With %-specifiers, it is possible to access the "argument" within the service.
/etc/systemd/user/battery@.service
[Unit]
Description=Logitech Battery Service

[Service]
ExecStart=/opt/bin/battery.sh %i

There is no dbus method in KDE to change the background (at least that I'm aware of), so I had to use a javascript snippet.
/opt/bin/battery.sh:
#!/bin/bash

declare -l status=$1

[[ ! $status \
=~ (full|(dis)?charging) ]] && exit 0

if [[ $XDG_SESSION_DESKTOP = KDE ]]; then

javascript=$(cat << EOF
const o = {
    wallpaperPlugin: 'org.kde.image',
    currentConfigGroup: [
        'Wallpaper', 'org.kde.image', 'General'
    ]
}
for (i in (d = desktops())) {
    Object.assign(d[i], o).writeConfig('Image', 'file:///opt/wallpapers/battery_$status.png');
}
EOF
)
    busctl --user call org.kde.plasmashell /PlasmaShell org.kde.PlasmaShell evaluateScript s "$javascript"

elif [[ $XDG_SESSION_DESKTOP = GNOME ]]; then

    dconf gsettings set org.gnome.desktop.background picture-uri "'file:///opt/wallpapers/battery_$status.png'"
fi

The script will look for images named battery_full.png, battery_charging.png, and battery_discharging.png in the directory /opt/wallpapers/.


sudo apt-get update stuck at 0% [Working]

It ended up being a problem with one of the sources. Specifically removing this line from /etc/apt/sources.list fixed it: deb [arch=amd64] https://download.docker.com/linux/ubuntu xenial stable.

After that I ran clean, autoclean and followed this guide which added the same source back in after which point it continued working.

Hopefully this will be useful if someone encounters the same problem.


apt-get wants an older GNUTLS version to be defined

Here is how I solved the issue. Note that it seemed a bit dangerous at the end, so a safer approach in another answer or in comments would be appreciated.

I found out there are two versions of libgnutls.so.30 on my system, one in /usr/lib/x86_64-linux-gnu and the other in /usr/local/lib/.

Running nm -gC and readelf -sW with grep on these files shows that the first one does contain the symbol in question and the second does not. This leads me to believe that the wrong copy of gnutls is being loaded at run time.

The file in /usr/lib/x86_64-linux-gnu is a link to libgnutls.so.30.14.10, and the one in /usr/local/lib/x86_64-linux-gnu is a link to libgnutls.so.30.13.1.

Confirmation: Running ldd on libgiognutls shows that it does try to link to the /usr/local/lib version.

More confirmation: Changing LD_LIBRARY_PATH did not work. Looking through the ld.so man page shows that this is probably because some elevated privilege is attained by the time ld.so is called.

Doing sudo su and then changing LD_LIBRARY_PATH. At this point, I am convinced that it is the link priorities of the two versions of libgnutls that is the issue.

Solved: I just took a leap of faith and linked the /usr/local/lib/libgnutls.so to /usr/lib/x86_64-linux-gnu/libgnutls.so file and the same with the .30 versions as well. So far nothing has broken and the error messages are gone.


Wine wont install. Seems like Ubuntu issue

wget -nc https://dl.winehq.org/wine-builds/winehq.key

and

sudo apt-key add winehq.key

source


how to save packages installed in one virtual machine and install them in another virtual machine in ubuntu

You have at least two alternatives:

if the packages are still in /var/cache/apt/archives you can copy them from there to the same directory in the new machine. Then apt will tell you it does not need to download them.
if they are no longer there, say because you did an apt-get clean for example, then you can repack them to recreate the deb packages and then move those to the new machine and reinstall them. Check this answer.


update-alternatives: error: alternative path /lib/plymouth/themes/MIB-Ubuntu/MIB-Ubuntu.plymouth doesn't exist

This will work, at least for me:

sudo apt-get --purge remove plymouth-theme-mib-ubuntu

If not, try this:

sudo dpkg --remove -force --force-remove-reinstreq plymouth-theme-mib-ubuntu

After that, you can re-install it with:

sudo apt-get install --reinstall plymouth-theme-mib-ubuntu

And make sure all package are fine with this check:

sudo apt-get update
sudo apt-get autoclean
sudo apt-get clean
sudo apt-get autoremove

I currently using Ubuntu Lucid 10.04 LTS, with Kernel 2.6.38.


What is the best video editor on Ubuntu for editing multi-format/multi-eco?

You could try OpenShot, which has also got some 3D Blender animations for titles, but it can be a bit frustrating.  Other user-friendly options are PiTiVI and Kdenlive.  As far as I've used them, you can easily join clips, insert text and images and export videos to different formats.  There is a list of open-source editing software on Wikipedia.

Within a few months Lightworks, a very professional editor, should be available for Ubuntu.

edit: Lightworks is now available for Ubuntu


Ubuntu 14.04 is totally broken, how can I reinstall from a new disk?

Sounds like: http://ubuntuforums.org/showthread.php?t=1917220
Try removing ~/.config/monitors.xml

monitors.xml is a file, not a package. Remove it from a terminal with the rm command:

rm ~/.config/monitors.xml


Recover unbootable Ubuntu, boot-partition gone?

You do not have grub installed in your MBR.

You can simply re-install grub from a live cd.

The process is a bit complicated, involves mounting a few partitions and installing grub.

Give this a try and keep us posted on your results.


Uninstall a flatpak software installations

I do not believe it was necessary for you to use sudo to install that.
In my case it wasn't.

List installed flatpak

flatpak list

    Ref                                              Options
com.github.philip_scott.notes-up/x86_64/stable   system,current
org.freedesktop.Platform.GL.default/x86_64/19.08 system,runtime
org.gnome.Platform/x86_64/3.34                   system,runtime

To run app:

Type notes-up in Activities

or in Terminal:

flatpak run com.github.philip_scott.notes-up/x86_64/stable

Remove:

sudo flatpak uninstall com.github.philip_scott.notes-up/x86_64/stable

flatpak uninstall --unused

Repeat with all other unwanted paks

Or for ALL INSTALLED flatpak:

sudo flatpak uninstall --all


The problem was not internet intermittence, but dns intermittence.
When I could not got to google.cl because of dns error issue, I did a ping to 8.8.8.8 google dns to check internet link and I got response. Then I knew the problem was related to dns.
Searching for the problem, I found that I missing dnsmasq but reinstalling it the problem was solved.
I don't understand why my default ubuntu 16.04 installation is missig for dnsmasq.


What you can do is use Ubuntu Server ( https://www.ubuntu.com/#download ). Ubuntu Server does have UEFI support. During the installation you will be asked to install server packages, just don't install any if you don't want to. After installation you will have a minimal Ubuntu with a commandline interface. Now you are able to install the packages needed to build the system you want.

Kind regards, Jeroen.


Like Jeremy31 said. Search in your Downloads Folder.

Try navigating to

  /home/"user"/Downloads

or

  /home/"user"/Public/

Where "user" is your Ubuntu Username, without the quotes (").


Constantly charging a battery reduces its total capacity, its ability to deliver power when disconnected. Therefore, charging logic is designed to restart charging only when the battery runs down to a specific voltage level, and this is normal.


How do you change the launcher icon to visualize the active workspace?

Not exactly what you've requested, which as answered is not possible but a decent alternative is the indicator-workspace. It displays the current WS number in the panel & allows switching WS's from it.

Available from this ppa

https://launchpad.net/~geod/+archive/ppa-geod

LP page

https://launchpad.net/indicator-workspaces


can't find library after updating Ubuntu [Ogre]

In Ubuntu 14.04, there are two versions of Boost: 1.54.0 and 1.53.0. 1.49.0 is not available.

Instead, you can install Ogre from the main repos (either libogre-1.8-dev or libogre-1.9-dev, depending on which version you want to develop on). This will ensure that when you upgrade to a new version of Ubuntu, the libraries that you use will be linked against the same version of libraries that are in the main repo. You'll only have to recompile your application.


How to disable sitcky screen edges in Ubuntu 18 Gnome?

you can do command line:

gsettings set org.gnome.shell.overrides edge-tiling false

needs reboot after


The default for automatically rebooting after unattended-upgrades is FALSE.

You can confirm on your own system by looking where the default value is stored, in the script itself:

grep 'Automatic-Reboot"' /usr/bin/unattended-upgrade

The default could change with a software upgrade, although that seems unlikely. To be certain your systems don't reboot by after automatic upgrades, explicitly disable rebooting in your configuration.


How to fix internal microphone which stopped working on Ubuntu 18.04?

I had a very similar problem. All the orthodox solutions didn't help. I solved it by fiddling around.
Here's the witchcraft that worked for me:

Connect another external microphone and select it (sound should work)

Disconnect the microphone you want to get working

Reconnect the microphone you want to get working

Input sound should now work again for this microphone by the means of black magic.


Why my usb mouse stays on after shutdown?

This is a "problem" of your motherboard supplying power even when computer is shutdown. I had the same with my old one. My keyboard was on all the time, as well as my mouse. No matter if computer was shut down or sleeping.


I was tricked into copy pasting a command, did it hurt me?

Nope, it didn’t do anything — it’s just a close call.

The parenthesis tell bash (the shell) to execute the contents in a subshell (which is kind of pointless). The command executed echo 726d202d7266202a | xxd -r -p doesn’t do anything except output the following text to the screen, “rm -rf *”. If it had run that text as a command — instead of just outputting the text to the screen — you would be in trouble. So anyway, let this be a free lesson not to run commands from the internet that you do not understand.


Change the language of the home/user/ folders automatically

When you told it to not ask you again, it probably removed the file

~/.config/user-dirs.locale

You can re-create that file. Assuming that the folders currently have English names, open a terminal window and run:

echo 'en_US' > ~/.config/user-dirs.locale


After upgrading to 11.10, when pressing Ctrl+F, Xterm is popping up

The culprit is xbinkeys, a software made to create custom shortcuts. The CTRL+F lauching xterm is an example in the configuration file (~.xbindkeysrc). Since Ubuntu 11.10 doesn't realise it is an example and use it by default, overriding all other uses of CTRL+F.

In order to set things back to normal do as follow :

Open your home folder, and press CTRL+H to show hidden files.
Open the file .xbindkeysrc (with gedit).
Add a pound (#) at the beginning of each line starting with "xterm" and the following one (most probably lines 46-47 and 50-51).
Save and exit.
Then either logout/login again or restart xbindkeys: killall -HUP xbindkeys


Try installing package simple-scan:
apt-get install simple-scan

It works for me with XP-202 203 203 Series
Good luck!


Why did Ubuntu 16.04.2 install the loader on Macbook Pro hard drive despite being told to put it on USB hard drive?

(This doesn't answer my direct question, but making it work proved more annoying than I expected so I thought I'd post some notes.)

In the end I seem to have got it working to my satisfaction. Armed with the ubuntu folder that the installer had added to my Macbook's EFI partition, my USB hard drive with an empty EFI partition, and @oldfred's comments, I filled the USB hard drive's EFI partition as follows:

make folder in root of empty EFI partition called EFI
copy ubuntu folder (that the installer added) into the new EFI folder
make folder in EFI called Boot
move EFI/ubuntu/grubx64.efi and EFI/ubuntu/MokManager.efi into EFI/Boot
move EFI/ubuntu/shimx64.efi into Boot, and rename it to BOOTx64.EFI
Edit EFI/ubuntu/grub.cfg, find the search.fs_uuid line, and remove the device specifier from the end (so it reads just search.fs_uuid <<GUID>> root).

My USB disk then appears in the Apple boot menu when it's connected. And when selected, it brings up the usual boot menu, and I can select Ubuntu and off it goes.

As a final step, once up and running, I edited /etc/fstab to mount the USB disk's EFI partition, rather than the MBP's.

(I don't know whether step 6 is vital, and I don't know whether these file names are case-sensitive. This took numerous reboots and I don't fancy doing much more additional experimentation.)


Unable to locate package libc6-dbg:i386 in docker

I'll answer this myself.

The information needed for figuring this out is at https://wiki.debian.org/Multiarch/HOWTO.

Apt in the official docker ubuntu image and also in phusion/baseimage is configured only with support for the amd64. This is what it tells you if you ask:

# dpkg --print-architecture
amd64
# dpkg --print-foreign-architectures
<no output>

The way to fix this is to add another architecture before the apt-get update:

# dpkg --add-architecture i386
# apt-get update
<lots of lines>
# apt-get install libc6-dbg:i386
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following extra packages will be installed:
  gcc-4.9-base:i386 libc6:i386 libgcc1:i386
Suggested packages:
  glibc-doc:i386 locales:i386
The following NEW packages will be installed:
  gcc-4.9-base:i386 libc6:i386 libc6-dbg:i386 libgcc1:i386
0 upgraded, 4 newly installed, 0 to remove and 21 not upgraded.
Need to get 7039 kB of archives.
After this operation, 26.4 MB of additional disk space will be used.
Do you want to continue? [Y/n]

For completeness, here is the final Dockerfile:

FROM ubuntu:14.04

MAINTAINER Me <xyz@example.com>

RUN dpkg --add-architecture i386
RUN apt-get update
RUN apt-get install libc6-dbg
RUN apt-get install libc6-dbg:i386


Gwibber Twitter "Authorise" button does nothing when clicked

I've "solved" this problem starting gwibber in a terminal : just type "gwibber" and click on the authorise button.

But once the account set, I can't receive news, the F5 button don't do anything... Any idea?

PS. Sorry for my English, I'm French :)


How do I resize partitions when I don't have physical access to a remote server?

Warning: The following does not work if you have ssh access to your server only!  You need some kind of an Out of Band console session into your server like a cpanel console, vCenter, iLO, IDRAC,  ...

Warning in plain English: You need to be able to see grub when you boot into Ubuntu.

The steps:

Take a full snapshot / system backup / ... of your instance that can be restored through a boot process like PXE, an off-line bootable USB disk, ...
No really: 95% of the time everything goes well, but have a look first on how to back up first before you have to trek up a mountain to service the Ubuntu server that is controlling that telescope!
Download the gparted live iso
copy the downloaded file in /opt/LiveISOs

    sudo mkdir /opt/LiveISOs
    sudo cp ~/Downloads/gparted-live-1.0.0-3-amd64.iso /opt/LiveISOs

edit /etc/grub.d/40_custom to include the following at the end:

    menuentry "GParted Live ISO" {
      set ISOFile="/opt/Live-ISOs/gparted-live-1.0.0-3-amd64.iso"
      loopback loop ($root)$ISOFile
      linuxefi (loop)/live/vmlinuz boot=live components config findiso=$ISOFile ip=frommedia toram=filesystem.squashfs union=overlay username=user
      initrdefi (loop)/live/initrd.img
    }

set grub's timeout parameter to anything but 0
update grub's config:

    sudo update-grub2

Reboot to grub
Take menu option GParted Live ISO

Voilà: a virtual USB key has been inserted in your VM / headless server / ... virtually and you can now shrink / expand partitions off-line using gparted (or using lvm utilities from the command line!)

Note: If using VMWare, you can also attach the ISO to the VM and boot the ISO through vCenter.


Why am I not able to send an email from command line

You need to install several packages namely as follows

 postfix mailutils libsasl2-2 ca-certificates libsasl2-modules

these packages are required for the proper setup of mail sending.
Here is a proper way of setting this up and testing out by sending mail and the possible troubleshooting.
Hope this helps :)


Docky not showing up in the task manager?

Even though you can start Docky with the command docky, when the application is running (whether with this command or auto-started on boot) it is later found in the task manager under the following name:

mono /usr/lib/docky/Docky.exe

Alternatively, you can also kill it from the terminal (this command should continue to work even if Docky switches from using Mono to using standard Linux binaries):

kill $(pgrep docky)


Using dpkg to install upgrade and dist-upgrade packages

Instead of using dpkg, which is a low level package manager, you'd be better off using apt. To install the .deb files using apt, copy them to the apt cache

sudo cp *.deb /var/cache/apt/archives/

and then just do the regular upgrade:

apt-get upgrade

The apt command will use the files in its cache rather than downloading it off the net, so that pretty much serves your purpose.


How to disable single mouse click folder opening?

For KDE

Open the System Settings from the Start Menu.Click Keyboard and Mouse Icon

Now click on Mouse,and then choose Double-click to open files and folders( select icons on first click)

Now single click is disabled..

For GNOME

In File Management Preferences,select Doulble click to open items.To access File Management Preferences,goto Places-->Computer (or type nautilus in terminal)

And then goto Edit menu from there select Preferences..


empathy "Facebook account requires authorization" problem

The telepathy-gabble 0.18.1 package in Ubuntu actually contained a work-around for the problem, not a proper solution. Quoting from the ChangeLog:

telepathy-gabble (0.18.1-1) unstable; urgency=low

  * New upstream stable release
    - work around Facebook server behaviour change so we don't consider its
      service discovery response to be spoofed (Closes: #721883)

 -- Simon McVittie  Mon, 09 Sep 2013 13:05:13 +0100

Apparently, this work-around does not work, and in fact the status of the bug has been reverted from Fix Released to Confirmed.

For the proper fix I'm sorry you will have to wait for the upstream bug to be fixed (unless someone proposes an another work-around in the meantime).


On the topic of adding the Fedora entry to the generated
Ubuntu menu list, 40_custom should look something like this.

#!/bin/sh
exec tail -n +3 $0
# This file provides an easy way to add custom menu entries.  Simply type the
# menu entries you want to add after this comment.  Be careful not to change
# the 'exec tail' line above.

# Boot Fedora's grub from partition
menuentry 'Fedora OS'
    recordfail
    insmod gzio
    insmod part_msdos
    insmod ext2
    set root='(hd0,msdos2)'
    kernel /boot/grub/core.img

Then run update-grub, if that doesn't end up working for you change the line
that says kernel and change it to linux.


It wouldn't work well with user nobody, because this account does not have a home directory to write into.

But given you have a normal user called otheruser, a very simple way to run a graphical application as another user is to use ssh X11 forwarding. For example with firefox, just do this

ssh -X otheruser@localhost firefox

and you should have a new browser instance running as user otheruser, but usable through your normal users GUI.

Obviously this approach needs sshd running, so in case you haven't installed it, run sudo apt install openssh-server first. If you are worried about adding a network daemon to your system you can configure sshd such that it will only listen to the localhost network interface, which is enough for above solution to work.


All you need is your so called 'profile' folder from your backup. This is a folder with the .default extension (the foldername itself will be some random numbers and letters ). It will be located in  ~/.thundebird .

In a clean install of mozilla thunderbird, you then need to copy that folder into the same directory on your newly installed Ubuntu machine. Then copy the name of the .default folder that was already there, delete that folder and give the foldername you copied to the folder from your backup. Restart thunderbird and you should be good to go.


Missing System Tray Icons in the Cinnamon Desktop Environment

I found the answer here:

https://unix.stackexchange.com/a/280807/116985

  It was found that "System tray" applet was disabled in my system.

  Fixed in this way:

  enter app menu type "Applets" and press "Enter" button
  on "Installed Applets" tab search for "System tray" applet
  select it and press "Add to panel" button

  some running applications might need to be restarted in order to appear in the tray


What should be content of grub2 custom entry to boot to another OS on LVM over LUKS along with Ubuntu?

Well here is the solution I found with help from arch forum:

Mount /dev/sda1 as /boot and enter the drive entry into fstab.

Now os-prober will show both ubuntu and arch.

The only problem with this setup is every time you update grub you need to change /boot/grub/grub.cfg as it  sees arch's linux image as main ubuntu's latest linux image and sends ubuntu in previous versions.


why wont python-pip install matplotlib work?

Based on the comments, you are missing some of the dependencies that matplotlib requires, namely libpng-dev and libfreetype6-dev. Install these dependencies by running:

sudo apt update
sudo apt install libpng-dev libfreetype6-dev


How to customize text color in Chromium tabs?

If you can edit gtk.css in your theme's gtk-3.0 subfolder, the line to edit is this:

@define-color theme_fg_color #aa55ff;

where #aa55ff is the new color.

Unfortunately, other aspects of the browser user interface will also be affected:

the text color of your bookmarks bar
the text color of items in folders of your bookmarks bar
the color of text in the Customize and control ... dropdown
the color of the back, forward, and home icons, and maybe more

And of course, all other gtk3 applications will be affected as well. If you don't want that to happen, make a copy of the theme with a different name and modify the copy. Then you can use

GTK_THEME=modified-theme-name chromium-browser

to run only chromium-browser with the modified theme.

Edit:

Even though you didn't ask about Firefox, I just like to point out that the Firefox user interface, even after Quantum, is currently far more customizable.

Here's what it looks like before tweaking the tab text color and tab background color:

And this is what it looks like after:

All I did was to create a userChrome.css file in the folder ~/.mozilla/firefox/profile_name/chrome. This folder doesn't exist by default. You need to create it.

The contents of userChrome.css to get the tab customization shown are:

tab { color: #000010 !important; font-size: 16px !important; font-family: Cousine !important; }
tab [selected] { font-family: Cousine !important; color: #ff00ff !important; font-weight: normal !important; font-size: 16px !important;  background: #444 !important; }

The advantage of tweaking the userChrome.css file is that no other aspects of the browser or other applications are affected.


Which group do you belong to:

  groups

All existing groups are in the file /etc/group. You would need just the first column of each entry (the fields are separated by colons). Thus:

  cut -d: -f1 /etc/group

New groups are defined using

  groupadd groupname

Groups are removed using

  groupdel groupname


How come WinX DVD Ripper software doesn't work?

WinX DVD Ripper is, as the name implies, Windows software. Ubuntu, as a Linux distribution, does not run Windows software. It is possible to install a Windows compatibility layer, Wine, which may help some of the software to work.

In general, it's better to install native Linux software though. Wine does not always provide full compatibility with Windows software, or the best performance.

For DVD ripping, I would personally recommend Handbrake, as this has been the easiest program for me. Handbrake is not available in the main Ubuntu repository, so I would refer you to this article on how to install it from a Personal Package Archive, or PPA.

http://www.thepowerbase.com/2012/03/install-handbrake-in-ubuntu-12-04/


can't log in with my password during ssh connection

You need to set this server-side. If you're unable to connect to the server at all to make these changes then you might be out of luck doing this remotely.

Try forcing password authentication first though:

ssh -o PreferredAuthentications=password -o PubkeyAuthentication=no student@<ip-address>

Once you've successfully connected through SSH you can change the server-side settings.

I suggest making a backup of the config first:

sudo cp /etc/ssh/sshd_config /etc/ssh/sshd_config.factory-defaults

Now, edit the config file:

sudo nano /etc/ssh/sshd_config

Locate the line stating PasswordAuthentication and set it to yes.

PasswordAuthentication yes

Save your file and restart SSH

sudo systemctl restart ssh

See this guide for further info on ssh configuration.


Save *.deb files from var/cache/apt/archives folder for future installation

Apt manager always install a software by reading source file which contains list of packages,there dependency. These list file are updated when you run the update program (basically whenever you run the command sudo apt-get update)

After a Ubuntu re installation those source files aren't updated.So you can update them using sudo apt-get update (Add PPAs if 3rd party software were used) and try with apt-get install method but wait, you may see that many files are being re downloaded (not all).

It is because those packages are updated with your previous installation of the software and now. Anyway in this case you have to download only the updated files. If the file hasn't updated it will take from your backup.You can see the required download size while installing.

Preferable Method

You can use apton-cd to create backup of apt-files (I don't know whether it will work in current situation, surely you can use it for future), mount the iso after re installation. Add the media as a source and install software.Lot of tutorial available in web.

Manual Method
Another thing you can do is to install using dpkg. Go to the folder of apt backup, run dpkg -i name_of_deb.deb. But in this way dependency won't be installed automatically. You have to install each dependent package individually. Other wise installation will fail. For example: to install vlc you have to install the libraries first and finding out the dependent library is not an easy task.

Note: I have told what I understand about installation in Ubuntu. Don't know whether any other method exists.


It is hard to be specific with the information you provided.  Are there any other processes running?  I suggest using tools such as top or htop to see which processes are burning CPU cycles to make the load that high.  Once you can clearly identify which are the definite offending processes we can then suggest ways to see if this is a problem or if it is expected.


Google chrome address bar font size is very small

If you are using Gnome, you can change your scaling factor in Gnome-tweaks until you are happy with the new size.


Bash: delete from cursor till end of line with a keyboard shortcut

Use Ctrl+K to delete from the cursor to the end of the line.

Use Ctrl+U to delete from the cursor to the beginning of the line.


Bluetooth Audio and SoftPhone Audio Input/Output

Wich softphone do you want to use?
I use Yate VOIP software and on the preferences you can choose another device for ringing and answering your phone.

So your music stays on the HDMI and your call is using your headset.
You only have to mute the music by yourself.

http://www.voip-info.org/wiki/view/YateClient


Unable to enter and plot negative data in SciDaVis and QtiPlot

If the default numeric format is switched to using . as comma, negative data is accepted! It seems muParser is unable to use negative data with , as data separator (?).


Logging all terminal input/output history

I don't know if you can install software on the server machine, but ZSH an FISH, alternatives to BASH shell, have timestamps store on their history files per command ran. In ZSH is stored per row and FISH use two rows per command. Both use Unix Time Stamp.
zsh
   : 1591635588:0;ssh user@server ls /tmp
fish
   989  - cmd: ssh user@server ls /tmp
   990    when: 1591387835

I use ZSH, with oh-my-zsh installed, instead of bash. ZSH's history file (~/.zsh_history) keep each command (row)stored as bash but puts at the beginning the Linux Time Stamp of the moment that command was ran. To keep the history at your side, client side, you can run the command via ssh:

$~> ssh user@server ls /tmp
$~> ssh user@server cat /etc/os-release

On ZSH it is store like so:

$~> cat ~/.zsh_history
: 1591635588:0;ssh user@server ls /tmp
: 1591636831:0;ssh user@server cat /etc/os-release

If you run AWK against the file you can translate the timestamps:

$~> awk -F":" '{print strftime("%Y-%m-%d %H\:%M\:%S", $2),$3}' ~/.zsh_history
2020-06-08 14:49:10 0;ssh user@server ls /tmp
2020-06-08 14:50:04 0;ssh user@server cat /etc/os-release

You can filter by date using together with grep, for example, and send it to a file:

$~> awk -F":" '{print strftime("%Y-%m-%d %H:%M:%S", $2),$3}' ~/.zsh_history \
| grep -E "2020-06-08" > ${HOME}/2020-06-08-history.log


Trouble setting up Lenovo IdeaCentre K450 usb boot

First, DO NOT ATTEMPT TO INSTALL LINUX IN BIOS/CSM/LEGACY MODE ON A SYSTEM IN WHICH WINDOWS IS BOOTING IN EFI/UEFI MODE!!!! In other words, setting "CSM" to "Enabled" and "Boot Priority" to "Legacy first" is the wrong thing to do! I realize that a lot of sites advise doing this, but they're wrong. Using a BIOS/CSM/legacy-mode boot will clear an initial hurdle, but it will put up two or three more down the road, so it creates more problems than it solves. People who advise doing it the hard way don't realize what they're doing because they do eventually clear those later hurdles, but they don't associate them with their initial mistake. (That said, there are some cases where using a BIOS/CSM/legacy-mode installation is the way to go, but they're the exception, not the rule.)

You should probably disable the "quick boot" option; this option often skips some or all of USB initialization, which renders USB devices unbootable. That's probably the immediate cause of your problem. Speaking of "quick boot" options, another one is at least as important: There's an option in Windows called "Fast Startup" or "Hybrid Boot" that you must disable, as described here.

On some computers, you may need to hit a function key (or sometimes Esc) just after powering on the computer in order to get a boot menu that enables you to boot from an external device. Unfortunately, the key you use to get this menu varies from one computer to another.

For more in EFI-mode booting, I recommend you read at least one of the following pages:

My page on EFI-mode Linux installations
The Ubuntu community wiki on the same topic
Adam Williamson's blog on how EFI works


The lightest of official Ubuntu versions is Lubuntu.
Also there is Ubuntu Netbook Edition specially designed for netbooks (discontinued currently).


removing windows 7 after ubuntu installation

Os -uninstaller is a small graphical tool to perform a clean and quick uninstall of any operating system (Windows, MacOS, Ubuntu, other Linux distribution..) of your computer.

boot your computer on a Ubuntu live-CD or live-USB.
choose "Try Ubuntu"
open a new Terminal (Ctrl+Alt+T), then type:

sudo add-apt-repository ppa:yannubuntu/boot-repair
- Press Enter

then type:

sudo apt-get update; sudo apt-get install -y os-uninstaller && os-uninstaller
- Press Enter

Using OS-Uninstaller
launch OS-Uninstaller (System->Administration->OS-Uninstaller menu if you use Gnome, or via the dash if you use Unity)

Then choose the OS you want to remove and click "OK"

http://pix.toile-libre.org/upload/original/1323945652.png

A confirmation window will appear:

http://pix.toile-libre.org/upload/original/1336577243.png

Click "Apply" to start the removal


Install i8kutils:

sudo apt install i8kutils

Next add to file /etc/modules the new line i8k:

echo "i8k" | sudo tee -a /etc/modules

Create and add to i8k.conf file new line options i8k force=1

echo "options i8k force=1" | sudo tee -a /etc/modprobe.d/i8k.conf

Now force i8k kernel module to load:

sudo modprobe i8k force=1

or just reboot your laptop.

Open file /etc/i8kmon.conf with nano text editor:

sudo nano /etc/i8kmon.conf

Add to the file the following strings:

# Run as daemon, override with --daemon option
set config(daemon)      0

# Automatic fan control, override with --auto option
set config(auto)        1

# Report status on stdout, override with --verbose option
set config(verbose) 1

# Status check timeout (seconds), override with --timeout option
set config(timeout) 20

# Temperature thresholds: {fan_speeds low_ac high_ac low_batt high_batt}
set config(0)   {{-1 0}  -1  40  -1  40}
set config(1)   {{-1 1}  30  60  30  60}
set config(2)   {{-1 2}  53  128  53  128}

# For computer with 2 fans, use a variant of this instead:
# Temperature thresholds: {fan_speeds low_ac high_ac low_batt high_batt}
# set config(0) {{-1 0}  -1  52  -1  65}
# set config(1) {{-1 1}  41  66  55  75}
# set config(2) {{-1 1}  55  80  65  85}
# set config(3) {{-1 2}  70 128  75 128}

# end of file

Now you can run i8kmon to check the cpu temperature and control the fan speed:

i8kmon

More information on i8kmon available from Ubuntu Manpage.


Installing guest additions on ubuntu 18.04 broke everything (Virtualbox)

I would advise you uninstall Virtualbox guest aditions on that Ubuntu guest machine :

open a terminal
type :

.

cd /media/$USER/VBox_GAs_5.2.18/
sudo ./VBoxLinuxAdditions.run uninstall

optional steps : get guest additions actually working.

you need to enable Vt-D : https://software.intel.com/en-us/articles/step-by-step-guide-on-how-to-enable-intel-vt-d-and-perform-direct-device-assignment

also make sure 2-D and 3-D acceleration is off for that Virtual Machine

boot it up and type :

sudo apt install virtualbox-guest-x11

this will be tested to work with your version of the kernel.


Screen distorted when installing Ubuntu Mate 20.04.1

Thank you Guiverc! The trick is in your link, which says to `

press “any key” as soon as you see this symbol

Once in safe graphics mode I can use this answer from Livipero Reposting in case someone else has the same issue and stumbles on this post.

Boot live ISO, select safe graphics. Complete installation and shut down.
On first boot, Hit "Esc" key to show GRUB menu, then "e" to edit, insert nomodeset at the end of the line that starts with "linux /boot/vmlinuz...". Press F10 to boot.
Login and open "MATE Tweak".
Select the third item from left panel: "Windows".
In the Window Manager , switch to "Marco (No compositor)".
Reboot (nomodeset will not be persistent so next boot is normal graphics mode).
Enjoy.


When does Juju re-read feature flag environment variable?

Feature flags are only read at bootstrap time.


Unity available from live-cd but not after upgrade from 10.10. How to fix?

No, your driver is ok. use ccsm (compiz config settings manager) and get rid of the conflicts, and you are good to go.


Can't run GNOME Shell extensions - Gtk-CRITICAL errors in gnome-tweak-tool

Update gnome-tweak-tool either from git-master or from the ppa:ricotz/testing PPA.
It has just been changed to fix compatibility with gnome-shell master.


Makefile error#2 when installing freeradius 2.2.8 eap libeap rlm_eap all modules all src all

Freeradius 2.2.8 does not build with the OpenSSL APIs of version 1.1.0 or 1.1.1 or newer.  This is documented in Debian Bug #828305.

As a result of this, if you must use version 2.2.8, you need to use an Ubuntu with older OpenSSL, which means you're going to be falling back to using Ubuntu Xenial 16.04.  That's currently the next older supported release of Ubuntu that might have older OpenSSL libraries available to it.

Failing this, however, if it also fails to build there, you will have to use a later version of FreeRADIUS and manually copy your configuration files, etc. over.  There does come a point where you cannot avoid 'updating' to newer software versions.


Ok this are the libraries I had to install to make this emulator run

because I am using an x64 system and epsxe is x32 i had to install 32 bit libraries

sudo apt-get install libsdl-image1.2:i386

sudo apt-get install libsdl-ttf2.0-0:i386

sudo apt-get install libgtk2.0-0:i386


Chromium blocks flash plug-in because it's outdated even after update

Found it:
Had to reboot Chrome (all windows) after disabling the faulty plug in. It works now, no more warnings.


Possible missing firmware /lib/firmware/rtl_nic/rtl8168d-2.fw for module r8169 with 2.6.38 kernel

I just fixed the problem by downloading firmware-linux-realtek from Debian.

first, let's make sure you still have the problem:

sudo update-initramfs -u

Now, if you still see the errors get the package:

cd && wget http://ftp.us.debian.org/debian/pool/non-free/f/firmware-nonfree/firmware-realtek_0.28_all.deb
sudo dpkg -i --force-overwrite firmware-realtek_0.28_all.deb

Let's verify the solution:

sudo update-initramfs -u

If everything goes well, you won't see the messages :)


Applications fail to launch in Ubuntu 20.04 Desktop

So... I found someone with a similar issue.
Using dmesg | grep GPU I confirmed my issue is indeed a GPU hang.
[  980.100449] i915 0000:00:02.0: [drm] GPU HANG: ecode 7:1:85ddfffd, in Xorg [3664]
[  980.204709] i915 0000:00:02.0: [drm] Xorg[3664] context reset due to GPU hang

As a temporary solution, until the Intel drivers have been updated, I've added nomodeset to my Grub configuration. Relevant instructions.


How to automate system configuration after reinstalling

Some well known tools for this (in my order of preference):

Puppet
Chef
cfengine

They do all require you to run a server to store the configs on though.


Shadowgrounds game series don't work under 12.04 64-bit

For Crayon Physics, this worked for 12.04 32-bit.

Go to the installation folder and rename lib32to lib32ORIGINAL.
In the terminal run the following command:

sudo apt-get install libqtcore4 libqtgui4

For 64-bit, try this:

sudo apt-get install ia32-libs libqtcore4 libqtgui4

In the terminal:

sudo apt-get install libsdl1.2debian libsdl-image1.2 libsdl-mixer1.2

For 64-bit:

sudo apt-get install i32-libs libsdl1.2debian libsdl-image1.2 libsdl-mixer1.2

cd to the installation folder and execute ./launcher.

I hope this works for you!


ROS Melodic Installation Ubuntu 18.04 (Bionic) in VirtualBox: "gpg: keyserver receive failed: No data"

UPDATE: Any change in the code has no effect. You need to run your code again until it works (or you add more download locations to go through in an if-statement so that the chance is less that you do not catch a download); see this answer.
I just leave the following old part as a proof that any placebo code changes did not help me, it was random and it strangely appeared at every first run, while at the second, it usually worked.

I had a similar thing, installing ROS Melodic, though in my case with Docker on WSL2.
I got  => ERROR [stage-1  2/11] RUN sh -c 'echo "deb http://packages.ros.org/ros/ubuntu bionic main" > /etc/apt/sources  3.5s ... gpg: keyserver receive failed: Cannot assign requested address:
#5 0.602 Executing: /tmp/apt-key-gpghome.CWiWk2Kd63/gpg.1.sh --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
#5 2.350 gpg: keyserver receive failed: Cannot assign requested address

I had to run it another time, and it somehow seemed to run through - I thought at first. This was the code:
RUN sh -c 'echo "deb http://packages.ros.org/ros/ubuntu bionic main" > /etc/apt/sources.list.d/ros-latest.list' &&\
    apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654 && \
    apt-get update && \
    apt-get install -y ros-melodic-desktop-full

But then I got a new error:
#5 353.2 Get:1306 http://archive.ubuntu.com/ubuntu bionic/main amd64 usb-modeswitch amd64 2.5.2+repack0-2ubuntu1 [53.6 kB]
#5 353.3 E: Failed to fetch http://archive.ubuntu.com/ubuntu/pool/universe/o/opencv/libopencv-core3.2_3.2.0+dfsg-4ubuntu0.1_amd64.deb  Hash Sum mismatch
#5 353.3    Hashes of expected file:
#5 353.3     - SHA512:6c5ee067a73d330eeea4ba0426f1f41a3021e1d91548ab7530706ba3d80b25df330bb37be2e753e1c87fbcd5d50f57c2e2de80ee91c59a80b69a8a6cc982bef5
#5 353.3     - SHA256:292740f9146eca5728a32cdf40a27efae4a724f76cf40601b8ef57368cde5bd5
#5 353.3     - SHA1:3a27b6ade543bd5f2ca5087ed3bf57b3df569d89 [weak]
#5 353.3     - MD5Sum:a629fdd926ae5e75fc878403a5409c1a [weak]
#5 353.3     - Filesize:708876 [weak]
#5 353.3    Hashes of received file:
#5 353.3     - SHA512:0fd63abb591a56fb4f0b790483b53df60037e2494a26913430cd5fb70ed21e05d3f0cc355562ce354f9ee07b9caf8d23a9d56d281e384ba973403dfd02a73cd4
#5 353.3     - SHA256:dcf88559ae189cde343f2be1e228d889ffa40746e0dcd9330600243606bbe949
#5 353.3     - SHA1:e5c14569a3bbfdb2e93f08535147e3547379c418 [weak]
#5 353.3     - MD5Sum:2d778738711f7745937060a2b50ba051 [weak]
#5 353.3     - Filesize:708876 [weak]
#5 353.3    Last modification reported: Wed, 26 Sep 2018 13:48:22 +0000
#5 353.3 E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?
#5 353.3 Fetched 556 MB in 5min 31s (1680 kB/s)
------
executor failed running [/bin/bash -c sh -c 'echo "deb http://packages.ros.org/ros/ubuntu bionic main" > /etc/apt/sources.list.d/ros-latest.list' &&    apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654 &&   apt-get update &&     apt-get install -y ros-melodic-desktop-full]: exit code: 100

I am not sure which code line caused that error. If it is caused by apt-get install -y ros-melodic-desktop-full, then it is beyond this question. I have solved that issue later. But if that error is caused by the first two lines, it is relevant enough to post it here.
Afterwards, the gpg: keyserver receive failed: Cannot assign requested address error appeared again.
Finally, it seemed to help adding more RUN's. And I post the other code lines that go beyond this question just to show the aim of it all: installing ros-melodic and python-catkin-tools.
RUN sh -c 'echo "deb http://packages.ros.org/ros/ubuntu bionic main" > /etc/apt/sources.list.d/ros-latest.list'
RUN apt-key adv --keyserver hkp://ha.pool.sks-keyservers.net:80 --recv-key C1CF6E31E6BADE8868B172B4F42ED6FBAB17C654
RUN apt-get update
RUN DEBIAN_FRONTEND=noninteractive apt-get install -y ros-melodic-desktop-full
RUN DEBIAN_FRONTEND=noninteractive apt-get install -y python-catkin-tools


Two warring package dependencies have completely blocked APT

Try removing gr-osmosdr too. sudo apt-get remove libgnuradio-iqbalance gr-osmosdr


How to connect to Ubuntu 17.04 Shared Network?

Answer found here:
Cannot share my Ethernet connection anymore after 17.04 install

Open Terminal and run:

sudo apt-get install dnsmasq-base

And even more, if you want to have custom IP for shared network do following:

nmcli connection modify $CONNECTION_ID +ipv4.addresses 192.168.5.1/24

where $CONNECTION_ID is found via nmcli connection show


Scanner wifi connectivity lost after upgrade to Ubuntu 13.04

Your version of Ubuntu is outdated, you must update to Ubuntu 14.04 with:

sudo apt-get update && sudo apt-get dist-upgrade

Then do the following:

http://printersquestions.com/How-to-install-Canon-PIXMA-MP980-on-Ubuntu.html


execute this in a terminal :

VIA APT-GET :

Using apt-get command line tool

apt-get is the command-line tool for handling packages. You can use following command options:

apt-get update: Update is used to resynchronize the package index files from their sources via Internet.
apt-get upgrade: Upgrade is used to install the newest versions of all packages currently installed on the system
apt-get install package-name: install is followed by one or more packages desired for installation. If package is already installed it will try to update to latest version.

Open terminal and type following two commands (Application > Accessories > Terminal):
Get update software list, enter:

sudo apt-get update

Update software(s) i.e. apply updates:

sudo apt-get upgrade


Trying to install a sw xdg-open: gnome-open: not found

If I understand your problem correctly - the application needs gnome-open executable.

It is available from libgnome2-bin package (see results from packages.ubuntu.com), so you need to install it with

sudo apt install libgnome2-bin

And xdg-open is usually pre-installed as part of xdg-utils package.


If I get your question right, you don't want autologin on your machine.

At startup it will run all the services it's supposed to run. No need for any specific user to be logged in (or auto-logged in) to achieve that.

If anyone connects a keyboard and monitor to the machine, he will get the welcome screen requesting login and password.

You may be concerned with what else a malicious invader can do if he gets a physical hold on your machine. But that's another story.


Everything but launcher and menu bar is black

Ok, that's extremely odd. Can you please try lgging from different account (Guest would do it too) to unity-2d and see if the issues exist?
If they do, try reinstalling Unity 2D packages.


Why can't I install software through my working Internet connection?

You need to disable the proxy when you're using your home network.

Your office proxy seems to be a local one (as it should be), as it's in a private IPv4 address space (172.16.x.x). As such, you can only connect to it when you're in the same network, i.e. you're connected to your office network.


Cannot set the screen brightness via PCI

I had the same problem. I installed a new software named Brightness Controller through which I'm able to control my brightness.
To Install use the following commands

Open terminal via Ctrl+Alt+T. Run command to add the PPA:
  sudo add-apt-repository ppa:apandada1/brightness-controller

Then update the respository and install the utility:
  sudo apt-get update
  sudo apt-get install brightness-controller

Done!!
Now remember one thing! You may have to adjust it again the next time you open your computer(means it is not permanent!)
Now if you want to remove the utility, simply run command:
sudo apt-get remove brightness-controller && sudo apt-get autoremove


My computer isn't loading GRUB when I boot

I suppose the problem was that grub was installed and configured to run ubuntu only because I chose "something else" when installing ubuntu, since I had no important information I reinstalled ubuntu but this time I chose "install alongside windows", therefore grub was installed and configured to prompt for which OS to boot.

that's what I deduced trying to solve this problem.

I hope this was helpful.


Differences between two versions of 14.04 Ubuntu

It sounds like that 'at the lab' you are running Ubuntu Gnome, and at home you are running Ubuntu Unity.  You can find information on the two at Difference between Unity and GNOME


Are Ubuntu DVDs available for buying in Canonical Store?

Update: The official Ubuntu Shop has closed down.

Pressed DVDs of Ubuntu 14.04 LTS desktop and server are now available to pre-order purchase from the Canonical store. The DVDs are only available in the 64-bit version. If you require 32-bit you will need to download a distribution or make your own DVD.

The store lists the following options (prices are current to January, 2015):

£5.04/$8.00 for a single disk
£8.50/$13.49 for a pack of 10
£18.20/$28.88 for a pack of 20

The Ubuntu 14.04 disks are no longer available from the Canonical store, however an 8GB bootable USB stick of Ubuntu 16.04 LTS Desktop is available from the official Canonical Store for $7.29.


No notification that an application is starting with Ubuntu 14.04. It's normal?

In Xubuntu the mouse pointer usually becomes a rotating ball when an application window has just apeared, until all the components ang graphics are loaded. For me this happens when I start nautilus.


WSL Ubuntu bash - Changing colors for user, host, directory information

WSL isn't designed to give you full Linux capabilities; that it works at all is amazing. Virtualization with VMware, VirtualBox, or other virtual engines is the preferred solution,


how can i use kbhit() function while using gcc compiler,as it does not contains conio.h file?

I use something like this as a substitute for for kbhit():

#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <termios.h>

char buffer[1];

int main()
{
  fd_set set;
  struct timeval tv;
  struct termios t;

  memset(&tv, 0, sizeof(tv));

  tcgetattr(0, &t);
  t.c_lflag &= ~ICANON;
  /*cfmakeraw(&t);*/
  tcsetattr(0, TCSANOW, &t);

  while (1) {
    FD_ZERO(&set);
    FD_SET(0, &set);

    select(1, &set, 0, 0, &tv);

    if (FD_ISSET(0, &set)) {
      printf("got input\n");
      read(0, buffer, 1);
    }
    else {
      printf("no input\n");
    }

    sleep(1);
  }

  return 0;
}

I only ever wanted to detect a keyboard hit as a way to exit some sort of forever loop for tests or whatever. However, I always forget to just hit any key, and tend to use ^C, so typically I also add a ^C handler in these programs so as to exit and cleanup gracefully.

void sig_handler(int signo){  /* do not abort on ^C */
   if (signo == SIGINT){
      printf(" --- SIGINT (^C) detected. Terminate gracefully, saving the sample data...\n");
      ctrl_c_flag = 1;
   } /* endif */
} /* endprocedure */

And to register:

   if (signal(SIGINT, sig_handler) == SIG_ERR){ /* register the signal handler */
      printf("\ncan't catch SIGINT\n");
   } /* endif */

   ctrl_c_flag = 0;  /* there has not been a ^C */

And then this to exit the forever loop and cleanup:

  if (ctrl_c_flag) break; /* exit on ^C */

Where ctrl_c_flag is a global variable.


There’s a way through dconf Editor; so:

open dconf Editor through the Dash;
go to org > gnome > settings-daemon > peripherals > touchpad;
check horiz-scroll-enabled, as you see in the screenshot.

Edit:
Dconf Editor was pre-installed on 13.04, where I first faced the problem; but on 13.10 and 14.04 it’s easier to use gsettings, see Samuel Cavazos’s answer.


Trouble starting mysqld on mysql cluster

I've had this issue a couple of times. Fixed it once, still working on the last one.  The one time I got it going I used brute force; I re-installed mysql-cluster (replacing existing files and packages) and since my config and start scripts were in custom directories they were unaffected. A reboot and auto-magically things worked. I think I had had an odd file permissions issue that the re-install fixed.


Imagine one of those cool stone walls without any mortar.

That's Ubuntu. It's made up of packages (stones) without any additional magic (mortar).
If you pull a package out, you can put it back in using the same tools.

You used Synaptic to remove a package, you can use Synaptic to put it back.

Many user-facing packages on top depend upon foundational packages at the bottom. You can remove those top user-facing packages without any harm. However, it's very unwise to pull out one of those foundational packages, since it will require the removal of lots of packages above it.

A log-reading application is one of those user-facing (top) applications. Nothing else depends upon it. If there had been dependencies, Synaptic would have warned you.

Ubuntu is merely a set of pre-curated packages that are tested to fit together. There's no magic. It's all open-source. Nothing is hidden. You can see how it's made and how the packages fit together (if you have the skills to understand -- it's a bit technical).


How do I upgrade from Ubuntu 10.10 to Ubuntu 11.04?

Ubuntu 11.04 is still in Beta (2nd Beta) and is due for release on 28th April, so until then, your update manager won't allow you to upgrade to the 11.04 (the reason being is unstable). You can upgrade to Ubuntu 11.04 from your maverick installation only through ISO of 11.04 (as it has option to upgrade during installation), but it is not recommended for production system, but it will be appreciated if you upgrade to unstable and report any bugs that you find, or you wait until 28th April to get fairly stable version of Ubuntu.


Always alert me install python-gevent but I have installed it

You already have python 2.7.5 on 14.04, I guess that you installed 2.7.8 manually in /usr/local and that your python interpreter is /usr/local/bin/python.

The problem is that the new 2.7.8 interpreter cannot import the system modules installed by apt-get.

I'd recommend to remove the 2.7.8 version, that way your proxy.py script should work.

You can quickly test your script with 2.7.5 with:

sudo /usr/bin/python proxy.py


Software center becoming fully transperent

Change the theme of the application window back to Yaru (bug). For some reason there an issue applying themes the certain windows.


How to get details for hardware with "This device is not working" message

There is a known bug is logged with Launchpad:
https://bugs.launchpad.net/ubuntu/+source/software-properties/+bug/1859308


Ok, I think I found it. Edit your /etc/default/grub file:

sudo nano /etc/default/grub

Change the following line:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

to say this instead:

GRUB_CMDLINE_LINUX_DEFAULT="acpi_osi=! acpi_backlight=native idle=nomwait quiet splash"

Press CTRL + o and then press ENTER to save the file. Press CTRL + x to exit nano.

Finally, update grub and then reboot:

sudo update-grub

source


Ubuntu unity launcher numbers to be always shown

I just had this same problem and was hoping to find an answer in this thread, but didn't.  My current solution:  physically tape little pieces of paper with numbers on them on the monitor bezel next to the launcher buttons.  I assume you were looking for an electronic solution, but what's the difference?

As an added benefit, if you have any passwords you need to write down, now you've got sticky notes on your monitor to use! ;)

Seriously though, get some paper and tape and you're all set.


It seems that it's related to recoverable system images or something for diagnostics. Please check in user manuals or call vendor.
You may damage a SW setup on the laptop if removed.

Regards.


Making a UDP application go through a proxy?

'System Settings -> Network' doesn't enforce a proxy. It merely recommends applications to use a proxy. (System Settings are Gnome settings and Gnome apps (and some others) use them. I believe, Firefox should also default to using Gnome settings, but I may be mistaken.)
The only way to enforce using a proxy, is a firewall that blocks all other traffic.
While SOCKSv5 supports UDP, SOCKS is more commonly used for TCP.
If you want a particular application to use a proxy, this application must support proxies.
If you want to tunnel all traffic (hide your real IP), consider using a VPN instead.


the link https://github.com/ubuntu/yaru says at one part from below quote "Installing from source is not recommended for average usage!"

  Using Yaru on Ubuntu

  The Yaru theme suite is installed with Ubuntu 18.10+ by default! No
  further steps are required to use it.

  Installing from source is not recommended for average usage! Using a
  legacy Yaru/Communitheme version on Ubuntu 18.04 (bionic beaver) via
  snap installation

Note that for backward compatibility, we kept the name "communitheme" for bionic beaver.

  Only icon and sound updates will be pushed into this version of the theme suite.

  These steps only work on Ubuntu 18.04 (bionic beaver)! DO NOT install
  the snap on 18.10+ installations!

  Follow these steps in order to install and enable communitheme.

Install the communitheme snap on 18.04 by installing communitheme in the Ubuntu Software Application or running snap install communitheme.

Restart your computer.

Click on your user, click on the gear icon and select the "Ubuntu with communitheme snap" session from the pop-up, and login.

Now Ubuntu is using the communitheme including the system, applications, icons, sounds and the cursor.

Installing from Source:

Tried it with live ISO and running install of Ubuntu 18.04.. In both cases.. It is observed that to build it from source, these packages are required.

meson sassc pkg-config libglib2.0-dev

So, Install the required packages with below command.

sudo apt install meson sassc pkg-config libglib2.0-dev

Download the file from this link https://github.com/ubuntu/yaru/archive/master.zip

Extract it.

Now create a script named yaru.sh with below content in your $HOME directory.

#!/bin/bash

cd $HOME/Downloads/yaru-master
mkdir xyz $HOME/YaruBuiltFromSource
meson setup --prefix=$HOME/YaruBuiltFromSource xyz
ninja -C xyz
ninja -C xyz install

run the script from your $HOME directory with the below command

/bin/bash yaru.sh

This script creates the required themes namely ICONS,CURSOR, GTK, SHELL, SOUND etc.. in the $HOME/YaruBuiltFromSource directory like below.

you can copy them based on your choice (for example for icon theme) to $HOME/.icons or $HOME/.local/share/icons or /usr/share/icons similarly for other themes also

Please note that you need to play tricks with symbolic links for Yaru shell theme..


proper way to install skype x86-64 in ubuntu 12.04 after recent skype upgrade

Errors like absence of /usr/lib/i386-linux-gnu/alsa-lib/libasound_module_pcm_pulse.so means that Skype needs libasound2-plugins:i386.

So my recipe that helps me is to run the following command:

apt-get install libasound2-plugins:i386


Your regex has two mistakes, a missing . before the first * and an extra ? near the end.

Here is some code that writes urls matching your pattern to urlsort using some python idioms.

#!/usr/bin/env python

import re

with open('urlfile', 'r') as urls_in:
    with open('urlsort', 'w') as urls_out:
        for line in urls_in:
            links = re.findall(r"(\/support\/security\/bulletins\/.*.html)", line)
            if links:
                urls_out.write("%s\n" % links[0])


The drop down above the results is the department selector.  Categories are the different groups of items in a scope's results, which is why you might have had trouble finding the correct API.

To add departments to your scope, you should call register_departments on the reply object in your query class's run method.  This takes a unity::scopes::Department::SCPtr object representing the set of departments visible for this particular set of results:

if the user is currently browsing the top level department, you should pass a Department representing the top level, with its immediate children filled in.
If the user is browsing a sub-department, you should pass a Department representing the parent, with its immediate children filled in.  The current department must appear within the children.

The idea is that only those parts of the department tree needed for immediate navigation are provided.  Your code might look something like this:

Department::SPtr parent = Department::create("parent", query(), "Parent Dept")
parent->set_subdepartments({
    Department::create("sibling", query(), "Sibling department"),
    Department::create("current", query(), "Current departmnet")});
reply->register_departments(parent);

Now all you need to do is make your scope provide results relevant to the department selected by the user.  This is made available in your query class as query().department_id().  This will match the ID of one of the departments you've previously registered, or "" which should be treated as the top level department.


One method for doing this would be to explicitly set the mount options through the disks GUI.

Step #1

Step #2

Navigate to the USB HDD.

Step #3

Select the partition on the USB HDD you'd like to have mounted read only.

Step #4

From the next window that you get, move the button to the left, under the option ‘Automatic Mount Options’, to get access to the settings.
Now, remove the check-mark under the option ‘Mount at startup’.
You can let it stay enabled too, but I prefer to let Nautilus (file manager) mount the partitions, after the desktop is loaded, to speed up the boot-up process.
Then, as shown in the below screenshot, you will see a field that says nosuid,nodev,nofail,x-gvfs-show.

Now all you have to do is, simply copy and paste the below code, and add (paste) it to the end of that text line (without a space). This will make the HDD mounted read only:

,ro

Step #5

Once done, click on the ‘OK’ button at the bottom, when asked enter your administrative password, and now you are done!.

Now try opening the partition in Nautilus (or any utility) and you will notice that you no longer can ‘Cut’ or ‘Delete’ files inside it, as it is mounted with read-only permissions.

To disable it later, you wanted to re-enable the read-write support, then simply remove that manually added ,ro code (or, you can also move that top button to the right side, until you see the option ‘ON), and save your changes. That's it!.

Source: How to Easily make ‘NTFS’ Partitions read-only in Ubuntu 12.10?


configure is a script (file) located in the source tree of a source distribution. There is no replacement for it in Ubuntu 13.10, if the source is the same it will still work.

Make sure that you navigated to the source tree of a project. Example instructions that are still applicable:

Download source.

wget http://bumblebee-project.org/bumblebee-3.2.1.tar.gz

Extract source.

tar xf bumblebee-3.2.1.tar.gz

Enter extracted source tree.

cd bumblebee-3.2.1

Run the configure script:

./configure --help


I suggest following: https://wiki.ubuntu.com/WubiGuide#How_can_I_make_a_backup_of_my_Wubi_install.3F

In a nutshell, take a copy of the entire "disk image" that Wubi makes. It will take up a bit more space to keep, but you're guaranteed to get everything :)

Copy it over to your new Windows installation (you will have to install Wubi there first, to get everything setup, such as the Windows bootloader. Then rather than use the new disk image it just made, copy in your backup.

Once done you have 11.04 on your new laptop. Now upgrade it using the usual methods (do-release-upgrade, or Update Manager) to 11.10. There is little chance of this failing, but if it does, you still have the 11.04 backup image to fall back to (assuming you keep another copy of it, which you should until the upgrade is done).


Why cat date.txt does not show any output

The shell's pipe (|) construct is for connecting the standard output of one process to the standard input of another.

In your case, you are redirecting standard output of the cut command to a file (> date.txt), and not reading standard input at all (since you pass a filename argument, date.txt, to the cat command). Appropriate shell conjunctions in this case are:

&& in which cat date.txt will be executed conditionally, depending on the successful exit status of previous commands in the pipeline

or

; in which case cat date.txt will be executed unconditionally

In this case, && is probably more appropriate (we won't try to read from date.txt if we were unable to write to it for example). So

date | cut --delimiter=" " --fields=1 > date.txt && cat date.txt

Unless you're just playing with pipes, you can avoid the cut by telling date to output only the abbreviated day name directly:

date +%a > date.txt && cat date.txt

You might wonder why date | cut --delimiter=" " --fields=1 > date.txt | cat date.txt doesn't work anyhow - since it's syntactically correct. The reason for this is that you can't rely on the order of execution of the LHS and RHS of a pipe - so cat date.txt is as likely as not to be executed before the output of the date command has been written to it.

In what order do piped commands run?


Hibernate doesn't work after a kernel upgrade in Ubintu 20.04

Updating my BIOS firmware worked for me!


I can't see "Install Ubuntu Enterprise Cloud" options in 11.10?

Ubuntu Enterprise Cloud was replaced with Ubuntu Cloud Infrastructure in 11.10. You can find information about that here:

https://help.ubuntu.com/community/UbuntuCloudInfrastructure11.10

and here for later versions:

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


Gephi crashes while loading the sample file

I figured out the answer and wanted to share with you guys. In the gephi website it is mentioned that in order to run the software we are supposed to type ./gephi in the command line. Instead try LIBGL_ALWAYS_SOFTWARE=1 ./gephi
This fixes any issues which occur while running the gephi software.


Matlab installation is stuck -- how do I abort it?

There are several ways to do this as described in the other question:

In System->Admin you have an application called System Monitor
you can also kill with xkill. Just go to the "run" dialog (Alt+F2), type in xkill and your mouse pointer will change to an "x". Point on the application that you want to kill and click, and it'll be killed.


Chainloading Legacy Windows 7 bootloader from EFI Grub2?

As mook765 noted in a comment, this cannot be done with GRUB. The trouble is that most EFI-mode boot loaders and boot managers, including the EFI-mode version of GRUB, can launch OS kernels in EFI mode and/or chainload to other EFI programs; but they cannot launch BIOS-mode boot loaders, which is what you need to boot your existing BIOS-mode version of Windows. I know of three exceptions to this rule:

The firmware's own boot manager -- Most recent EFIs with BIOS-mode support (provided by a Compatibility Support Module, or CSM; also referred to as legacy-mode boot support) provide a built-in boot manager that enables you to switch between native EFI-mode and BIOS/CSM/legacy-mode booting. You typically enter this boot manager by hitting Esc, Enter, or a function key as the computer is powering on. This can be awkward, and in some cases it's not supported at all.
rEFInd -- My rEFInd boot manager supports switching from EFI-mode to BIOS-mode booting. On Macs, this ability is enabled by default. On UEFI-based PCs, though, you must edit refind.conf: Uncomment the scanfor line and ensure that hdbios is one of the options. Since you're trying to boot Windows from a second hard disk, you might need to uncomment the uefi_deep_legacy_scan option, too -- but I recommend doing this only if doing it without that option doesn't produce an option that boots Windows.
rEFIt -- This is rEFInd's predecessor project. It supports BIOS/CSM/legacy-mode booting on Macs only. If your computer is a UEFI-based PC, it won't do the job. If you've got a Mac, you could use rEFIt for it; but as rEFIt has been abandonware since 2010, rEFInd (which I'm still developing) is probably the better choice.

Note that all of these options require that the firmware provide a CSM, and that it be enabled. AFAIK, all Macs (with their latest firmware) and most UEFI-based PCs provide a CSM, but a few UEFI-based PCs lack this feature. If you've got such a computer, your only choice is to convert the Windows installation to boot in EFI mode. See this page for instructions on how to do this. You might want to go this route even if your computer provides a CSM, since a CSM slightly slows and complicates the boot process. OTOH, it's likely to be easier to set up rEFInd or use the built-in boot manager. You may need to enable the CSM in your firmware setup utility. Details of how to do this vary from one computer to another. Typically, there's an option called "boot mode" that you'd set to "UEFI or legacy," or some variant on these option names.


Wired connection to LAN but no internet after upgrading to Ubuntu 16.04

I was having the same exact issue and found that in my case, it was Kernel that needed to be updated.

First download the packages. This one is for 64 bit.

$ wget kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc2/linux-headers-4.9.0-040900rc2_4.9.0-040900rc2.201610232131_all.deb

$ wget kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc2/linux-headers-4.9.0-040900rc2-generic_4.9.0-040900rc2.201610232131_amd64.deb

$ wget kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc2/linux-image-4.9.0-040900rc2-generic_4.9.0-040900rc2.201610232131_amd64.deb

Next, install the packages.

$ sudo dpkg -i 'linux-headers-4.9*.deb' 'linux-image-4.9*.deb'

And finally, reboot.

sudo reboot

Here are the packages for 32 bit machines.

$ wget kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc2/linux-headers-4.9.0-040900rc2_4.9.0-040900rc2.201610232131

$ wget kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc2/linux-headers-4.9.0-040900rc2-generic_4.9.0-040900rc2.201610232131_i386.deb

$ wget kernel.ubuntu.com/~kernel-ppa/mainline/v4.9-rc2/linux-image-4.9.0-040900rc2-generic_4.9.0-040900rc2.201610232131_i386.deb

Install the packages.

$ sudo dpkg -i 'linux-headers-4.9*.deb' 'linux-image-4.9*.deb'

Reboot.

sudo reboot

If that doesn't work, you can uninstall with the this code:

sudo apt-get remove 'linux-headers-4.9*' 'linux-image-4.9*'


GDM does not display session, or top row icons

I found that the issue is that some icon themes are not being applied correctly.

What I did to resolve my issue.

Reinstalled using synaptic all files relating to: gnome-shell* gnome-session* gnome-icon* gnome-desktop gnome3
Using GDM3SETUP applied a theme

Not sure why there is an issue here, probably has something to with the initial installation which was Xubuntu.


How to Add PCloud in startup applications?

To find the command:

  Most default applications will have a .desktop file located in
  /usr/share/applications.

  To find out about the corresponding terminal command that will be run
  when launching one of these applications open the file browser
  Nautilus and right click on the application's icon to select
  Properties in the context menu. [Then, look at the "command" box]

Taken from here

Then:
Dash > Startup Applications

Add a new entry, and in the "command" box, put the command to launch this program from CMDline.

Please note, it may not start instantly after logon. It might be 30 seconds before it opens.


Note: DNS is broken in 18.xx, with/without VPN.

Problems...

your /etc/resolv.conf is a hard-wired file and should be a symlink
your /run/resolvconf/resolv.conf and /run/systemd/resolve/resolv.conf are not getting populated
you installed openresolv
you followed a two-year-old script from github (+ for trying though)
systemd-resolved is disabled and not running
you're missing some required network-manager packages

So... just to start...

uninstall openresolv
remove all mods based on the github link
re-enable and restart systemd-resolved

sudo systemctl enable systemd-resolved # re-enable systemd-resolved

sudo systemctl start systemd-resolved # start systemd-resolved

sudo systemctl status systemd-resolved # check the status

recreate the /etc/resolv.conf symlink

sudo rm -i /etc/resolv.conf # remove the hard-wired file

sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf # recreate the symlink

sudo ln -s /run/resolvconf/resolv.conf /etc/resolv.conf # recreate the symlink

reboot # reboot the system

after reboot...

cat /etc/resolv.conf # check the contents of /etc/resolv.conf

and confirm that it contains something like 192.168.x.1 or the IP address of a upstream DNS server.

We'll modify your .ovpn scripts, import them to NetworkManager, and test VPN later. One thing to note is that using sudo openvpn script_name.ovpn may produce different results than importing the .ovpn file into NetworkManager.

For your .ovpn files...

Add the following at the end of the file (try this with only one of your .ovpn files).

script-security 2
up /etc/openvpn/update-resolv-conf
down /etc/openvpn/update-resolv-conf

then try...

sudo openvpn script_name.ovpn # connect via cli

cat /etc/resolv.conf # recheck the contents and confirm changes

resolvectl # check that DNS servers are getting assigned to tap0

Check for DNS leaks at http://dnsleak.com

Update #1:

I've changed my mind (at least temporarily) and have decided to change the symlink in the step "recreate the /etc/resolv.conf symlink"...

recreate the /etc/resolv.conf symlink

sudo rm -i /etc/resolv.conf # remove the symlink

sudo ln -s /run/systemd/resolve/resolv.conf /etc/resolv.conf # recreate the symlink

sudo ln -s /run/resolvconf/resolv.conf /etc/resolv.conf # recreate the symlink

resolvectl may not show the expected result for device tap0 with VPN up

Update #2:

Now we'll import the modified .ovpn file into NetworkManager.

open the Network settings panel
locate the VPN section, and click the "+" icon to add a connection
select Import from file
locate your modified .ovpn and import it
once imported, click the "ADD" button
use the NetworkManager's VPN menu to connect to your VPN Server using the imported .ovpn
check for DNS leaks at http://dnsleak.com
resolvectl should show the expected result for device tap0 with VPN up

Update #3:

installed missing packages...

network-manager-openvpn

network-manager-openvpn-gnome

network-manager-vpnc

need to check for these (dpkg -l *resolv* | grep ii)...

resolvconf

libnss-resolve

Update #4:

Here's a screenshot of the "Wired Connection" NM script that I'm talking about... you can set DNS there (remember to set DNS AUTO to OFF, and then enter comma-separated DNS IP addresses)... or edit /etc/systemd/resolved.conf and edit the #DNS= line... however either of these might override the automatic handling of DNS with VPN that we're trying to get at 100%.

Remember that using sudo openvpn client.ovpn produces slightly different results than initiating a VPN connection from NetworkManager with an imported .ovpn script. In either case, you'll want to monitor the two resolv.conf that we have symlinked to /etc/resolv.conf and see which one appropriately shows the DNS servers from either your local network, or the VPN network, but normally not both... then adjust the symlink if required. (note: we may have to also edit /etc/nsswitch.conf... more on that later).

Remember that I said that DNS is kind of screwy in 18.xx :-) I finally got mine working pretty well, but it took some time.

Update #5:

Something to try... I have not played with this myself... so report back with your results.

Edit /etc/nsswitch.conf and temporarily comment out:

hosts:  files myhostname mdns4_minimal [NOTFOUND=return] dns

and put this in its place:

hosts:  files mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns myhostname

Update #6:

If this is confusing... remember I said it might be...

Here's a test for you to run... take careful notes, as it's easy to get it wrong from memory... I know I did...

Let's just purely look at the output of resolvectl. There are 3 different places that we have to look to see if it's actually working right.

Global
       LLMNR setting: no
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
  Current DNS Server: 10.200.0.1 <--note
         DNS Servers: 10.200.0.1 <--note

and...

Link 5 (tun0)
      Current Scopes: DNS
       LLMNR setting: yes
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
  Current DNS Server: 10.200.0.1 <--note
         DNS Servers: 10.200.0.1 <--note
          DNS Domain: ~.

and...

Link 2 (eth0)
      Current Scopes: DNS
       LLMNR setting: yes
MulticastDNS setting: no
  DNSOverTLS setting: no
      DNSSEC setting: no
    DNSSEC supported: no
  Current DNS Server: 192.168.0.1 <--note
         DNS Servers: 192.168.0.1 <--note
          DNS Domain: ~

Run two separate tests...

Test #1...

use the CLI, sudo openvpn client.ovpn
note, using the above 3 examples, if your VPN DNS shows up anywhere
go to http://dnsleak.com and check for a VPN IP and for DNS leaks

Test #2...

use the NM interface to connect using your imported .ovpn file
note, using the above 3 examples, if your VPN DNS shows up anywhere
go to http://dnsleak.com and check for a VPN IP and for DNS leaks


Will Editing HOSTS file in Ubuntu Improve my Network Security?

You should use 127.0.0.1, the so-called loopback address. Unlike 0.0.0.0, it is a valid IPv4 address.

While it is true that this mitigates some tracking issues, this does not improve security per se.

There are a gazillion sites that track you, and you can't keep up editing your hosts file. To prevent tracking, you'd better use plugins like AdblockPlus and NoScript that auto-update the list of sites to block.

Also note that security is a process, not some setting or configuration.

To strengthen your security, you also need to consider

setting up a firewall
physical access to your machine
lots of other things that would be out-of scope here.


Mount the windows shares using smbfs (for instructions check http://www.debian-administration.org/articles/165), then just copy from the terminal using rsync.


Renaming files by adding "cycling" suffix

With find + the perl based prename (aka rename on some earlier Ubuntus) you could match the sequence of digits before a literal . and then write it in the desired format using modulo division e.g.

find . -name '*.tif' -execdir prename -vn -- 's/(\d+)\./sprintf "%dc%d.", $1, ($1-1)%3+1/e' {} +

(the -vn flags alllow you to do a 'dry run' to see how the files would be renamed before committing).

Ex. given

$ tree
.
├── bar
│   ├── file1.tif
│   ├── file2.tif
│   ├── file3.tif
│   ├── file4.tif
│   ├── file5.tif
│   ├── file6.tif
│   └── file7.tif
├── foo
│   ├── egg
│   │   ├── file1.tif
│   │   └── file2.tif
│   ├── file1.tif
│   ├── file2.tif
│   └── file3.tif
└── spam
    ├── file1.tif
    └── file2.tif

4 directories, 14 files

Then

find . -name '*.tif' -execdir prename -- 's/(\d+)\./sprintf "%dc%d.", $1, ($1-1)%3+1/e' {} +

results in

$ tree
.
├── bar
│   ├── file1c1.tif
│   ├── file2c2.tif
│   ├── file3c3.tif
│   ├── file4c1.tif
│   ├── file5c2.tif
│   ├── file6c3.tif
│   └── file7c1.tif
├── foo
│   ├── egg
│   │   ├── file1c1.tif
│   │   └── file2c2.tif
│   ├── file1c1.tif
│   ├── file2c2.tif
│   └── file3c3.tif
└── spam
    ├── file1c1.tif
    └── file2c2.tif

4 directories, 14 files


Installed Ubuntu with "Erase Disk" option, all partitions deleted

"Erase Disk and Install Ubuntu" completely wipes the target drive(the one you are installing to) and allocates the entire drive for Ubuntu. Unfortunately, all the data on the drive has been overwritten, and your partitions are unrecoverable. You will have to restore from backups.


Installing 11.10 on fresh VirtualBox client hangs - how to debug?

I tried the following without resolving the problem, but they may be useful to know:

increasing client HDD space to 9GB (it actually won't install without this)
increasing client memory to 1GB (apparently there may be problems with only 512MB)
disabling client network adapter to stop the installer trying to make network connections

In my case, I needed to change my client storage options, which solved the problem with hanging:

Option 1: ext3

Ubuntu 11.10 creates an ext4 partition by default. This debian-installer bug gave me a hint to try an ext3 partition instead. When I did this, the installation completed successfully.

Option 2 (preferred): Enable host I/O cache

However, I think a better solution is to create a new client machine and then tick "Enable host I/O cache" on the SATA controller of the client machine (find it under Storage on the client machine settings). [1] [2] When I did this, I could successfully install Ubuntu using the default (ext4) partition options, which I prefer for no other reason than that it is the default.

Other candidates

If this didn't help you try:

checking if you need to install third-party software (thanks John)
running the memory test on both your host and client machines (you'll find the memory test as one of the options in the first menu of the installation CD/DVD) (thanks Barafu)

How to debug? I don't know.

I posted here on AU, the VirtualBox forums, and solved it by searching for my specific symptoms. I still don't know how to retrieve error messages from the installer itself.


Problem solved. The 'init' process is in fact a crypto-mining process, not the system process init. I deleted the malware and now everything has back to normal.


Do Ubuntu kernel updates happen automatically?

New Ubuntu kernels do get installed as part of normal update and upgrade procedures. For example, this week my 16.04 kernel version went from 4.4.0-34-generic to 4.4.0-36-generic when I ran my daily sudo apt update && sudo apt full-upgrade

If you don't run those commands very often, you will get prompted by a pop up to update software when important updates like a new kernel are available. You have to authenticate these updates, they won't happen otherwise, as @AndroidDev points out.

The system will always boot the newest kernel by default. After a kernel update, it's a good idea to run sudo apt autoremove to remove older kernels (it leaves one extra spare older kernel)

If you want to install a newer mainline kernel (4.6*, 4.7*) for some special reason then you must do so manually, but this is rarely a good idea, as the Ubuntu kernels are patched and configured to work well with Ubuntu.


I have solved the problem described in the OP by removing cordova-cli and installing Cordova via npm like this:

sudo npm install -g cordova