How come after first install can only boot in recovery with video=800x600 acpi=off nomodereset hp mini 1030 14 lts

If you've got the black bar at left and repeated top inch of window at bottom, it's hardware... keep your clamshell mostly closed (only an inch or two open to allow the screen wires and hinges to stay clear of each other.

Power down, close clamshell, open clamshell just an inch or two, power up. If it doesn't work give the closed laptop a few **GENTLE* knocks upside it's noggin on the side to make the wires giggle just a bit, then repeat power down and power up with clamshell open just a bit.


After installing ubuntu 14.04 my windows 8.1 seems to be missing?

It looks like it deleted your NTFS partition

I took a quick look, and this utility might let you restore the lost partition:

https://apps.ubuntu.com/cat/applications/precise/testdisk/

Hope that Helps


Did you try scrolling down to windows vista sda1 or sda2
and Press Enter?

One of those partition is vista, the other is Vista Recovery Utility.
In my computer sda1 is vista and sd2 is the recovery.

You can also access the Vista Recovery Utility when you turn on the computer from
HP bios Screen. In mines you type F11 but yours may  be different.

If you want revert to boot in windows follow this instructions from Microsoft
http://support.microsoft.com/kb/927392
from the recovery utility console.

You will have to do some disk cleaning, afterwards to recover the space.


Ubuntu amd64 instead of i386 - cause for slow booting?

No, i386 is for 32-bit CPUs. amd64 is for 64-bit CPUs, like your i5. There is never a speed difference when on a 64-bit CPU.

DO NOT switch to the i386 version of Ubuntu. It will, in some cases, actually slow your computer down further by limiting it to 2 GB of RAM.


ASUS Eee PC 1215B: Washed Out Display with AMD Catalyst drivers

These settings work fine for me:

Brightness -10
Contrast 70
Saturation 120
Hue -30
Temperature 6300


Add and Remove a Shortcut on Applications Tab and Dock

Use this application It allows you to create, edit, or delete everything you see in the applications dialogues (Launchpad, applications menu).


How do I edit a file in /proc that can be viewed with cat, but is not editable by mousepad and abiword?

/proc (manpage, kernel docs) is a virtual filesystem (as is /sys - kernel docs). Files in /proc aren't real files, but ways to access information and settings from the kernel. You shouldn't use an editor to edit files in /proc, but write directly to these files:

sudo sh -c 'echo foo > /proc/some/file'
echo foo | sudo tee /proc/some/file

When you attempt to read or write from it, the kernel converts the actions to system calls internally and does the right thing. Some editors can still view the contents (try Vim, for example), but writing to it is a different story.

For a special class of files, those in /proc/sys (kernel docs, Arch Wiki), there's another alternative. You can use the configuration files in /etc/sysctl.conf and /etc/sysctl.d/*.conf to make permanent changes to their values. A file /proc/sys/foo/bar can be set using a key foo.bar in one of these files.

For example, /proc/sys/vm/swappiness can be set by adding a /etc/sysctl.d/90-swappiness.conf containing:

vm.swappiness = 10

And running:

service procps start

You can also make one-off changes (that won't survive the next reboot) by using the sysctl command directly:

sudo systecl -w vm.swappiness = 10


How to permanently remove "@public.talk.google.com" contact from Pidgin?

If you haven't found out, its to do with people in your google+ circles.
Source:
http://productforums.google.com/d/msg/gmail/OhaG1DWHoXs/AqpOnnRj9ZMJ

Remove this person from your google+ circles, or follow the instructions on:
http://www.gaumire.com/2012/02/01/i-appear-publicly-on-google-talk-a-wtf/
or turn it off completely:
 http://possiblyuseless.wordpress.com/2014/02/07/how-to-get-rid-of-public-talk-google-com-contacts/

I know this is a little late, but thought it might be helpful to someone else.


processes came into halt and new started process halt as well

It seems that simply killing some processes will renew the long halted remaining tasks.


Simple way to consistently access a SMB mount?

Gigolo is an SMB broswer with an 'autoconnect' option when you bookmark a share. Click on the icon to install gigolo (from Software Center or sudo apt-get install gigolo) and it's pretty easy from there.

(Another answer, no extra apps, but it's not perfect: Navigate to the location in Nautilus and Add a Bookmark (Bookmarks -> Add, or CTRL-D). Each login you'll need to navigate to the share to mount it (sorry!), but once you have, it will be mounted in /home/username/.gvfs/ )


How to start / stop a process using a .sh file?

To run the .sh files:

give them execute permissions chmod +x start-conlfuence.sh stop-confluence.sh
to run: sudo ./start-conlfuence.sh or sudo ./stop-confluence.sh

Or easilu you can just run by the command sudo sh start-conlfuence.sh or sudo sh stop-confluence.sh


How to paste a code to terminal and execute it line by line? (it has sudo)

Pasting multiple commands at once may lead to problems if one of them waits for terminal input. In this case the rest of the paste will be taken as input for that command and not as separate command to be run afterwards. The most common example is probably the sudo password prompt.

However, Bash is capable of opening a text editor to enter commands, by default it is nano. You start the command editor by pressing Ctrl+X followed by Ctrl+E. The editor launches and everything you typed into the current command line so far will also appear there and can be edited. If the command line was empty though, the editor will be empty as well.

In the editor you can now easily paste or type multiple commands, simply put one command per line and Bash will execute them one by one. You can also put a whole script in there, it does not matter. The content you write gets internally saved as temporary file and executed almost like a Bash script. The only difference here is that if you have multiple commands, Bash will first print the command itself before executing it.

If you're done with editing and want to submit your list of commands, simply exit the editor (Ctrl+X for nano). It will ask you whether to save the changes and you answer "Yes" and hit Enter to accept the proposed temporary file name. Bash will then start to execute all the commands one after the other.


Apache permissions to allow both user and web server to edit /var/www

It's possible to set different group and user access for files and directories, and this will allow both Apache and your user1 user to edit what's in /var/www without requiring root/sudo and without making anything world-writable.

So, set the "user" permission inside /var/www to user1.  Set the "group" permission to www-data (but ONLY for the specific files or directories that the web server needs to write to).

sudo chown -R user1:user1 /var/www
sudo chgrp www-data /var/www/specific-file

You should avoid letting the web server write to the entire /var/www directory and its contents, instead giving the above group permission only to the specific files where this is necessary.  It is a good security principle to limit the web server's access to write to files to only those files that it is strictly necessary for - and it is a good idea to try and ensure those files are not executed directly (aren't .php or other executable scripts, for example).


How to Silence Commands Being Broadcast?

You have inadvertently turned on Screen Reader.

Go to System Settings -> Univalsal Access -> Click the Screen Reader On/Off switch to off.

You can also use the Keyboard Shortcut: Alt+Super+S


Directly connect Windows and Ubuntu computers via ethernet cable

The short of it is, unless you've got a really bad router, that's probably just as fast as anything else.

The following are the main bottlenecks exist in a network for file transfers in the order of most likely to be limiting you.

Bad wireless chipsets (some Broadcom) are capped at low speeds like 72mbps so won't give you more than 9MB/s.
100mbps network hardware will limit things to a maximum of 12MB/s
Average 300mbps wifi will stop you going faster than 37MB/s
Slow hard disks (5400rpm laptop disks for example) will cap out at 40-70MB/s
Faster 7200rpm disk are then there at about 110MB/s write
Gigabit hardware and great wifi (802.11AC on dual band) will raise its head now at ~120MB/s
Average SSDs will cap out at 100-200MB/s
Good SSDs will cap out at 500-1000MB/s
10gbps ethernet will predictably limit you to ~1.2GB/s provided the hardware is good.

Even with a direct (no router, no switch) network, you're limited by your crappiest component. In the laptops, we're talking about cheap 100mbps ethernet adaptors and those energy efficient hard disks.

And while I'm talking about routers and switches, most of these can allow massive throughputs. Many cheaper gigabit routers will allow ~200+MB/s to flow through them. Routing is not an expensive procedure.

If you need to move something fast and often, you're probably going to need to overhaul a lot of hardware.


You need to source your script. If not it will be run in a separate subshell, changing the working directory of the subshell but not of the shell you run it in.

To source it :

. myfile.sh

or

source myfile.sh

You can read more here


Follow the steps described below

1: add the PPA maintained by Ondrej Surý

sudo add-apt-repository ppa:ondrej/php

2: update the system

sudo apt update

3: install PHP versions 7.2

sudo apt install php7.2

4: Select the standard version of PHP

sudo update-alternatives --set php /usr/bin/php7.2

5: Disable version 7.4 or the one you are using

sudo a2dismod php7.4

6: enable version 7.2

sudo a2enmod php7.2

7: Restart the apache server

sudo systemctl restart apache2

Hope this helps!


How often are the regional mirrors of ubuntu updated?

Here is a list of mirrors where it also mentions how up to date it is.

  How often are the local servers of ubuntu updated?

It depends on the local server. They pull the software in at their convenience.

But specific to Nepal (you have 1 mirror): Nepal Telecom is one day behind for Yakkaty Yak and up to date for all other releases.

If you look at my country below it (Netherlands; 16 mirrors) it shows a mix of "up to date", "one day behind", "1 week behind" and even "unkown".


How can I force turbo boost work constantly in Ubuntu?

Turbo-boost is on "all the time" by default in the default ondemand CPU governor.

But that doesn't mean the clock speed is always the turbo boost's level all the time and certainly not for all cores. Turbo boost allows the CPU to scale up one or two cores (depending on the CPU) to an overclocked level on demand. This will happen in Ubuntu.

What you can't (and shouldn't) do is try to turbo boost while overclocking. I'm not even sure it's possible. You'd be mixing two things that shouldn't be mixed.

But what you can do is set a manual overclock in your BIOS. CPU scaling will probably still happen but that isn't an issue because ondemand is just as fast as the performance governor in most situations. You can set it if you wish.


Windows cannot read the Linux filesystems without third party drivers.

You have several options,

use FAT32 --does not support Linux permissions so you will have issues with files that need to maintain ownership.
use NTFS --also does not support Linux permissions, also susceptible to corruption(Linux will have issues with a corrupted NTFS)
use EXT file systems and install third party drivers in Windows

The program you need to install in Windows is Ext2Read

for more detailed info on Ex2Read see the sourgeforce page(in the link above), or the page I used as my source for this answer: How to read Ext3/Ext4 linux partition from windows 7(this page also tells you how to install and use Ext2read as well as screenshots).

If you wish to also use Windows to write to the Ext file system then you would need to install Ext2Fsd, this is also mentioned on my source page.

Personally, if I only needed to access the EXT files(read only) I would avoid Ext2Fsd ; I don't have any reason to doubt the program, I would be afraid that Windows would clumsily botch the files(I have no hard facts for this opinion, but as Microsoft has no love for Linux, they have no reason to prevent regressions in their updates that would injure a Linux FS).

Disclaimer:   I no longer use Windows so I cannot test this information, but ubuntugeek.com is a good website and I would use this info and the program myself if I needed it.


There is unfortunately no settings option provided for that. There's only option to show and hide the name

$ gsettings list-recursively com.canonical.indicator.session
com.canonical.indicator.session show-real-name-on-panel true
com.canonical.indicator.session suppress-logout-menuitem false
com.canonical.indicator.session suppress-restart-menuitem true
com.canonical.indicator.session suppress-shutdown-menuitem false
com.canonical.indicator.session suppress-logout-restart-shutdown false
com.canonical.indicator.session user-show-menu true


How can I bypass a wireless switch which is broken on a Sony Vaio VGN-FW31E?

I believe the module that translates key presses to action in your device is sony-laptop. Confirm with:

lsmod | grep sony

If so, you might remove it temporarily:

sudo modprobe -r sony_laptop
sudo rfkill unblock all
rfkill list all

If that enables your wireless and there are no other negative effects, blacklist it so it never loads in the future:

sudo su
echo "blacklist sony-laptop"  >> /etc/modprobe.d/blacklist.conf
exit


Free URW postscript fonts versus TrueType

Many people would argue that Postscript fonts are actually superior to TrueType. In fact, in a professional setting, Postscript and OpenType are used more frequently than TT. Advocates of TT argue that TT allows for better hinting (note that PS fonts can also have hinting), even though in many cases the popular fonts do not take full advantage of TT capabilities. PostScript fonts used to look jagged on vintage Windows machines without Adobe Type Manager, but that is the past.

Bottom line is, you will not notice much difference between the free TT and PS fonts, at least not in the price range you are paying.

See also:

Purple Fusion Graphics: Font Wars: PostScript vs. TrueType vs. OpenType
TrueType & PostScript Type 1: What's the Difference?


Dependency problems installing eViacam on 12.04

libcv2.1 isn't available on Ubuntu 12.04 (according to packages.ubuntu.com it was replaced by libcv2.3). You'll need to contact the author of that PPA, which it seems the only way to do so is via their forum and ask if eViacam is compatible with libcv2.3 and if so, if they will update their packaging in the PPA to depend on that package rather than libcv2.1.

The same thing happened for libhighgui2.1 (it was replaced by libhighgui2.3) so you'll want to ask about it at the same time.


I had similar problems with Ubuntu 18.04 LTS on Notebook model: DELL LATITUDE 7400
The black screen was (violet'ish color of grub)
I can boot either with linux 4.15.0-1087-oem or 4.15.0-1081-oem but only when I boot up from the power button.
But hangs if I power up from plugin AC or USB-C Dock cable or if I use software reboot.
So I uncheck in the BIOS the options "Wake on Dell USB-C Dock" and "Wake on AC" in "Power Management" section. And try not to use reboot with software command but use the power button.
I thinks the issue is with Grub 2.02.
I modified /etc/default/grub with the following:
GRUB_DEFAULT="1>0"
GRUB_TIMEOUT_STYLE=menu
...
GRUB_TIMEOUT=30
GRUB_CMDLINE_LINUX_DEFAULT=""
GRUB_CMDLINE_LINUX=""

So now when I reboot(with software command) it display indefinitely "loading kernel 4.15.0-1087-oem"
But I can boot when I power up my laptop using the power button (with plugin AC or USB-C Dock cable) and selecting manually kernel 4.15.0-1087-oem in grub menu.
it seems the auto selection of kernel in grub 2.02 doesn't work well on dell latitude 7400 laptops!


My computer is not receiving the 16.04.1 update

I had this issue too. Following this answer:

You can see what version you have by running:

lsb_release -a

And you can upgrade by running (apt instead of apt-get):

sudo apt update && sudo apt upgrade

Let me know how it works?

And, yes, you would see 16.04.1 instead of 16.04. Here is a screenshot of my output:


Compiz doesn't work after trying to enable the desktop cube

Fresh installs don't include it with Compiz. You should install it via the terminal or the Ubuntu software center.

Via the terminal you should type:

sudo apt-get install compizconfig-setting-manager

Then, enter your password and wait.

Via the Ubuntu software manager you should type compiz and then install it.

I hope this is useful.


"OpenOffice decided not to have a learning curve"

The OpenOffice.org and LibreOffice office suites have retained a traditional interface that most users (of them or any other office suite) are likely to find familiar and pretty easy to use, without having to learn it or get used to it first.

In contrast, some other office suites, including newer versions of Microsoft Office, have implemented substantial interface changes, often again and again with each version. These changes arguably introduce some substantial benefits, but at the cost of confusing users and making them learn something new. Learning new things is great, but most people don't use word processors and spreadsheet software for its own sake.

While making sure users continue to be able to migrate from Microsoft Office is a substantial consideration that goes into the development of OpenOffice.org and LibreOffice, it's worth taking note that these office suites have deliberately not changed their interfaces to mirror the newer Microsoft Office interfaces. It's more important that OpenOffice.org and LibreOffice users be able to use OpenOffice.org and LibreOffice without interruption, than for people who have only used new versions of Microsoft Office to be able to switch to them without having to figure anything out.

Fortunately, the OpenOffice.org and LibreOffice interfaces are designed reasonably intuitively and they are well-documented (with pretty good help materials), so people who have only used office suites with different interfaces should be able to learn to use them without too much difficulty, even many years from now.

  "Firefox tries very hard to make sure pages written in 1995 look like they did in 1995."

The Firefox web browser is written in such a way as to maintain backward compatibility as well as possible with old web content. Not only should old web pages load and function as well as they did with browsers that were current when the pages were created, but they should do so seamlessly (without the user having to enable any sort of "compatibility mode") and they should look as close as possible as they used to look...or at least as close as possible to the way they looked with previous versions of Firefox.

  "Windows isn't a poor man's Linux."

Either the reverse is intended ("Linux isn't a poor man's Windows"), or this statement is unclear and needs to be modified and/or further explained. Either way, this should probably be reported as a bug in Ubuntu's community documentation. Perhaps you would be willing to do this? In any case, if we wait for some more answers here, maybe we can gain more insight into what may be intended by that statement, which could help in reporting the bug.

EDIT: There's been a great deal of speculation in comments and answers as to what "Linux isn't a poor man's Windows" means. Several peripherally similar but ultimately different ideas have been proposed. I think this shows even more strongly that this sentence is unclear, and that its current form in documentation for novices constitutes a bug.


You likely have the drive mounted in /etc/fstab using /dev/sdX and the identifying letter got changed. Drives get assigned a letter by the order they are found. Make a live USB stick and fix your /etc/fstab.

lsblk

will show the drives.

Also, its a good habit to mount drives in /etc/fstab using an UUID rather than /dev/sdX. You can find out the UUIDs with

sudo blkid


To install Dash Reports:

Download the binary core tar.gz of Apache Tomcat 7.0 (Assuming Java 1.6 or higher is installed; This method is easier than using Ubuntu's package management which delivers Tomcat using tight security settings)
Unpack it somewhere in your home folder (I will be using ~/bin/apache-tomcat-7.0.52)
Download the latest release of Dash Reporter
Put the .war in Tomcat's webapps folder (eg, ~/bin/apache-tomcat-7.0.52/webapps/dashreports-1.1.war
Start Tomcat from the command line

Go to Tomcats's binary folder: cd ~/bin/apache-tomcat-7.0.52/bin
Start the Tomcat server: ./startup.sh

In your browser go to: http://localhost:8080/dashreports-1.1
Log in with the default credentials

Username: admin
Password: password

Some basic Dash Reports usage:

Add your database via Manage -> Datasources (if you connect to a remote database, make sure your database user is allowed to connect from the machine where Dash Reports is installed)
Create a chart

Go to My Groups -> Example Group (this is the default; you can create different groups)
Select Chart from the pull-down menu and click Add
Type a name and insert your SQL query (it is easiest to create your query in your normal database management program like for example HeidiSQL)
An example of an SQL query output useable by Chart:

| NAME | AGE |
--------------
| Mary | 25  |
| John | 23  |
| Kate | 27  |

Under the Layout tab you can set the size of the chart and once you have multiple charts, grids, etc. you can arrange them using Display Column and Display Row
Under the Schedule tab you can set when the query has to be run in order to refresh the chart (default is once every minute)
For the chart to work, go to tab Chart Details and fill in the Y-Axis Label, X-Axis Column Name and Value Column Name


My Toshiba's fans do not work automatically

This has been reported here and here and here (kernel).

There appears to be one workaround:

Boot up
Suspend
Wake it up
ACPI should work (fans should work, the lid should sleep it, etc)

If this doesn't work, I recommend you don't run Ubuntu until it's fixed as letting it overheat is very dangerous to the hardware.

Of course if you can help the kernel devs find a fix for this, the faster you get the fix.


How to view FAT32 Ubuntu files from Windows 10?

You seem to admit this in your question, but using FAT32 is not a good idea for installing your Ubuntu system.  It doesn't even have basic security features expected by Linux.

It is better to set up a system partition for each OS using an appropriate filesystem for that OS, and then have a separate partition which is to be shared by both OSes.  While FAT32 is an option for such a partition, NTFS is probably a better choice now as FAT32 still has that 4GB file size limit, very relevant these days, and it's a little easier to corrupt if your computer doesn't shut down cleanly.  NTFS is now supported well by most operating systems, including Linux.

That said, I don't know why your FAT32 partition isn't showing on Windows.  That may be a Windows issue that you'll need to sort out, if you do want to continue trying this.


Oracle Java 7 as default and one in the system?

Yes, it's okay to do so, unless you're running some software that specifically requires openjdk. Most probably you are not. Also, yes, you can install IcedTea back later on if needed.

man 8 update-alternatives tells

   automatic mode
          When a link group is in automatic mode, the alternatives system
          ensures that the links in the group point to the highest priority
          alternative appropriate for the group.

   manual mode
          When a link group is in manual mode, the alternatives system will
          not make any changes to the system administrator's settings.

Basically, in automatic mode, installing new package might change the default. In manual mode, what you choose will stay.


Opera web browser in Ubuntu Software Center

Opera used to be available in the Canonical partner repository (software in the partner repository is available in the Software Centre), but it was removed in December 2008 (the version in the repository at the time was very out of date).

My analysis of this is that there is not a huge desire in the Ubuntu community for Opera, but if either Canonical or Opera had a strong desire to have it there, then it certainly could happen again.


How do I disable Firefox push notifications in Kubuntu?

In System Settings → Notifications, under "Application progress", uncheck the "Show in Notifications" checkbox.


What the difference between the output of kill -l on Bash and Zsh?

Use which command

as can be seen below, those are different implementation of kill. zsh uses an internal one.

zsh:

~ % which kill
kill: shell built-in command

bash:

~$ which kill
/bin/kill


Dell N5110 Touch pad Scroll bar not recognized in Ubuntu 12.0.4

I had a similar problem with my alps touchpad.  It worked on 12.10, but not on 12.04.  (Have you tried yours in 12.10?)  I wanted 12.04, however, so what I ended up doing was testing newer and newer kernels.  I ended up with the 3.6.3 kernel, and everything is working great.  (If you try this, of course do the research & take the necessary precautions, e.g. back-up.)


Ubuntu 16.04 second monitor goes black after login

Sounds like a problem with your Nvidia drivers. Nvidia drivers (especially ones downloaded from Nvidia website) are notorious for wreaking havoc on your GPU-enabled laptops. Have you checked your System settings -> Software & Updates -> Additional drivers? How many drivers do you see there? There should be Nvidia drivers (atleast one) and possibly an X-server Nouveau (open source).

1) If not try running
sudo apt-get install xorg xserver-xorg; sudo dpkg-reconfigure xorg or sudo apt-get install xserver-xorg-video-nouveau
This should install the Nouveau. Try switching it to that driver in the Additional drivers menu and restart and see if that solves the problem.

2) If you have older Nvidia drivers try installing new version:
sudo add-apt-repository ppa:graphics-drivers/ppa
sudo apt update && sudo apt install nvidia-<number>. The number I have is 390, but you can try 380, 387 etc.

3) Switching to Nvidia driver can cause you to run into a login loop in which case you need to press Ctrl+Alt+F1 at login screen, and type:
sudo apt-get purge nvidia-* and
sudo dpkg-reconfigure lightdm and
sudo reboot -i to switch back to nouveau and get back to your desktop


http://localhost/example/ test.php not working?

In short, to access http://localhost/xampp within the default configuration of XAMPP you must:

Create a sub dir called xampp/ into the DocumentRoot directory. The default DocumentRoot of XAMPP is /opt/lampp/htdocs/ - source:

sudo mkdir /opt/lampp/htdocs/xampp

Create a simple index.html or index.php file:

echo '<?php phpinfo(); ?>' | sudo tee /opt/lampp/htdocs/xampp/index.php

The above command will create index.php file in the directory /opt/lampp/htdocs/xampp/, that will contain the code: <?php phpinfo(); ?>.

If that works and you are able to see a page as this shown here, you must read the documentation of XAMPP and some relevant articles to gain a basic knowledge: How to setup a Virtual Host locally with XAMPP in Ubuntu.


Trouble installing Elementary desktop environment on Ubuntu 15

Open a terminal and run

mkdir somedir
cd somedir
sudo apt-get install -y debhelper
wget http://archive.ubuntu.com/ubuntu/pool/main/u/ubuntu-extras-keyring/ubuntu-extras-keyring_2010.09.27.{tar.gz,dsc}
tar -xf *.tar.gz
cd ubuntu-extras-keyring-2010.09.17
debuild -i -us -uc -b
sudo dpkg -i ../ubuntu-extras-keyring_2010.09.27_all.deb

After that, elementary-desktop will install, but will error out at the end because it depends on systemd-shim which is no longer needed nor wanted with 15.04 having a full SystemD implementation.

When it errors out, run

sudo dpkg --force-depends -r indicator-datetime
sudo apt-get purge unity-control-center unity-control-center-signon

and it should complete the installation.


I'm battling with the same issue for a different linux OS.  Just some brief comments: note that my 'experience' (ha!) is with RAID 0; if you are mirroring from first to second disk (RAID 1) then some of what I suggest below may not apply - others much more experienced than me may help better.

you haven't said what RAID (0 or 1) you set up.
The RAID'd disks should appear as one device - if you do anything at all to individual disks I suspect you may kill the raid.
linux will use either mdadm or dmraid to assemble the raid array, and present the RAID device in /dev/mapper/(something).  dmraid is older and reportedly barely /not maintained, but some folk need it if dual-booting with MS-Win on the same RAID.  mdadm is the supposedly preferred modern alternative (but won't work on my hardware).  From my reading of Ubuntu discussions, I think U uses mdadm behind the scenes for your install.
If the raid is recognized/assembled, then in /dev/mapper you should see a file called 'control' and then  a file with a name like md (the whole raid device), plus md1, md2, md3 representing any partitions in the whole raid device.  The names might be much longer but should resemble each other with different numeric endings.  If you've only got the 'control' device and one other device, then I guess you've not created any partitions on the RAID yet.
You report it fails with "The RAID arrays all say: /dev/mdx doesn't contain a valid partition table".  I suspect that means just what it says; either the raid array has not been assembled (by mdadm) or more likely you haven't created a partition within the RAID on which to do the install. (or you're trying to look on the individual drives rather than looking at the RAID in /dev/mapper)
Installations are done to the raid device representing the partition you want to install on, in /dev/mapper/9something).  Don't go near /dev/sda or /dev/sdb; they are not the raid device and basically don't exist if you are in RAID 0.

Hope that much perspective helps, and is not out-of-keeping for how Ubuntu does it.
Tonyb


How to Extend Ubuntu 18.04 Manually Configured Disk?

the tool you're looking for is resize2fs

Or alternatively parted

check this answer out : https://askubuntu.com/a/517365/307184
you'll have to use it's subcommand resizepart passing it the arguments partitionnumber and endpoint


Can't do sudo commands on a user account that has no password

Since you are the main user who needs administrative privileges to install software, you should give your user id "bob" administrative privileges. If you are the only user on this computer, then you only need one account and it should have administrative privileges. Ubuntu will safely run "bob" with out administrative privileges until it is needed (example installing software). Ubuntu will then ask you for your password allowing you to run an administrator task.
If your home folder and documents are already saved under "bob", I would give "bob" administrative privileges first and then delete the "smallcomputer" user. To do this you will need to login as "smallcomputer" first:

Log in as "smallcomputer"
Go under "system settings" > "user accounts" > select "bob" > select "unlock" button in upper right window > authenticate "smallcomputer" by entering in "smallcomputer's" password > change "Account Type" to "administrator" > select "Password" and enter a secure password > log out of "smallcomputer"
Log in as "bob" and you should have to enter a password. Go under "system settings" > "user accounts" > select "smallcomputer" > select "unlock" button in upper right window > authenticate "bob" by entering in "bob's" password > you can delete the account "smallcomputer". If you do not want to delete the account, you should change the account type to "standard" for security purposes.


You shouldn't be that worried if you have not installed the nvidia driver on the newer computer in the same way that you did on the first one. There are a few things you should be aware of.

First:

the nvidia drivers will use dkms if it is installed when you manually install the driver. Before installing the nvidia driver, run the following command:

sudo apt-get install dkms

Then, you may install or reinstall the nvidia driver and should not have any issues updating to new kernels and will not have to reinstall the drivers after updating kernels.

Next:

you should be able to log in from grub using the old kernel. Select "Advanced Options" and then select the older kernel from the next menu. This will give you a way to use the machine until you install dkms and reinstall the driver (on the older computer).

Finally:

You can manually apply updates on any machine using the command-line and doing so will offer two options. Run the following commands in an open terminal.

Option one:

sudo apt-get update
sudo apt-get upgrade

Using the above option is safe and should not perform any updates that will break the system. This way, you can perform security updates and other bug fixes without disrupting the system. This is for when you are working on a project or using the machine for production and need to maintain function.

Option two:

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

This option will perform all updates including kernel upgrades and other updates that  make changes to the system and could affect the overall function. Use this when you are not in the middle of a project and have some time to fix any problems that may arise. Problems are not likely but are possible as you have found out. Also, problems are not typical. Installing dkms before manually installing nvidia should prevent future issues.


The simplest way is to have GRUB remember the last boot choice made at the GRUB menu.

Edit /etc/default/grub and change/add the following lines near the top of the file...

GRUB_DEFAULT=saved    # change an existing line to this

GRUB_SAVEDEFAULT=true # add this line

Then...

sudo update-grub # update the GRUB menu

reboot # reboot the system


"exec: gnome-session: not found" when logging in using lightdm

Resolved. There was a syntax error in .pam_environment. I missed out the DEFAULT in

PATH DEFAULT=${PATH}:${HOME}/MyPrograms

See Ubuntu help wiki page on environment variables


Reducing bitrate in conversion of mp3 and ogg

Do not do this. Transcoding from a lossy format to another lossy format will only decrease quality. You won't save any meaningful space. No matter if it is from mp3 to mp3, ogg to ogg or mp3 to ogg. You will lose quality. They are called lossy formats for a reason.

Do the test yourself: convert the same song 5 (or 10) times from 128 to 128. Yes, same bitrate. Quality will be inferior than original file. Every conversion introduces artifacts that will lower the perceived quality. A file that was transcoded from 320 to 256 than to 160 will sound worse than if encoded directly from source to 160

If you really want to save space, get your original, un-encoded, lossless files, and convert them once to your desired bitrate. My strong suggestion? Go VBR. lame's -V5 for casual listening (average ~130, much higher quality than any other 160 or 192 CBR), or -V3 if you're very picky about quality.

Do not use CBR if you're trying to save space. Its a dumb format: why keep a constant, say, 160 kpbs if some passages of the song would require much less than that to achieve "perceived perfection"? Those "wasted" bits could be used more efficiently in other passages where complexity (lots of instruments, multiple (and high) frequencies, etc) would require more bits.

VBR can do that. Goes up all the way to 320 when that is needed, to keep quality, and reduce down to 96 (or less) to save space when it doesnt require many bits for same perceived quality.

In other words: VBR's are both more economical (saves when not needed) and higher quality (increases when needeed). A wise choice if you want a good balance between less disk space and great quality.


Software Updater and Software & Updates are two separate apps even though their icons are similar in Ubuntu 20.04.


How to optimize RAM memory in Ubuntu 12.04?

I have 2Gib of RAM but I think system uses too much.

You got this wrong: the more used the better. RAM not used is RAM wasted.

  The Internet goes slowly

RAM usage is not the cause for this. Your connection itself is the slowest part when it is about connecting to internet.

  Can you tell me if I have to do something?

Nothing to be done here. At least not based on that image alone.


Replace ack with ack-grep on a prebuilt VM?

You have several options, depending on your specific needs and preferences.
In this situation, it's best not to manually remove and rename these files, because:

Something might need them.

Your changes might be partly or fully undone when you update your system.
(You could tell the package manager not to do so, but that's not likely to be the easiest way to achieve your goal.)

And, consistent with the first two considerations, you've expressed a preference to completely uninstall the existing ack, which just removing that one file will not generally do.

So it's better to check if /usr/bin/ack appears needed and, if not, remove it with the package manager. But you probably do not need to remove it at all, as detailed below.
Ubuntu Packages Search reveals that in Ubuntu 12.04, /usr/bin/ack is provided by the ack package.
Uninstall ack, after making sure it's safe to do so.
You don't have to uninstall ack: if you use the alias way, or put a symbolic link in /usr/local/bin, or in your private ~/bin, it will be run even if /usr/bin/ack remains installed. Thus this is actually optional.
Run apt-get -s remove ack to simulate a deinstallation of ack. This will reveal what other packages, if any, depend strongly enough on ack that they would be uninstalled along with it.
Feel free to expand your question with the output of that apt-get -s command, if you want help or confirmation in determining if removing ack would also uninstall anything possibly important.
If no other package removals are revealed, or if you know the other packages that would be removed are also unneeded, you can then proceed with the real removal operation:
sudo apt-get remove ack

That is, for the real thing, omit -s (and run it as root with sudo).

The Alias Way
As Brian Z suggests, making a shell alias so ack runs ack-grep may be sufficient for your needs. This will:

affect just your user account.
not typically work in scripts (so if the reason you need it to be ack is you have scripts that call ack, this won't be sufficient).
not work for commands like sudo ack ....

But it is quick, easy, simple, and often sufficient.
If you want to create something that can be used in all the ways an "installed" ack command can be used, you can skip the following section (and continue at "Symlinks are good...").
Making an Alias to ack-grep called ack
If you decide a shell alias is what you want, the best way to make it is probably to put it in .bash_aliases in your home folder.
That file probably doesn't exist yet, but if it exists when you start a shell (for example, when you open a new Terminal window or tab), it will be used. This is because .bashrc runs when the bash shell starts, and that file checks if .bash_aliases exists and runs what's in it if it does.
Run gedit ~/.bash_aliases. In the text editor, write alias ack='ack-grep' and save the file. The alias should work for all shells started after that.

Symlinks are good for running commands under alternate names.
If you don't want to make an alias (or doing so wouldn't give you what you need), a symbolic link is probably what you need.
When you create your ack command, it's better for it to be a symbolic link to ack-grep rather than a copy, because then when ack-grep changes (for example, if it is upgraded to a newer version), ack will run the new version automatically.
Places Programs Can Go
You could put the new ack in /usr/bin, but I recommend making it /usr/local/bin/ack instead. /usr/local/bin is probably in your PATH environment variable already, ahead of /usr/bin. For example, on my machine:
$ echo $PATH
/home/ek/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games

In Ubuntu, /usr/bin is one of the normal places for the system's package manager to put executables. /usr/local/bin is one of the normal places for you to put software you install yourself. This is not quite that situation, in that you're just making a link to run software that's already installed. But it's similar, and more importantly, stuff you put in /usr/local/bin is much less likely ever to conflict with anything created or managed by Ubuntu's package manager, than if you put it in /usr/bin.
Or you might prefer to create the symbolic link in your home folder. If you do this, it will work for your user account, and not affect any others. If you prefer this, skip down to "Alternative: Make the Symbolic Link in ~/bin."

Making the Symbolic Link in /usr/local/bin
To create a symbolic link /usr/local/bin/ack, pointed at /usr/bin/ack-grep, run:
cd /usr/local/bin
sudo ln -s /usr/bin/ack-grep ack

If the cd command fails with bash: cd: /usr/local/bin: No such file or directory, make the directory with sudo mkdir /usr/local/bin and try again. (Even if the directory doesn't yet exist, it may be in  your PATH environment variable, in which case your ack command will be run.)
If /usr/local/bin Isn't in $PATH
To check if programs in /usr/local/bin (including symbolic links to programs elsewhere) will be run--or troubleshoot if they aren't being run--you can see if /usr/local/bin is in your PATH environment variable. To do that, run echo $PATH.
It probably is there, but if not, you can edit the PATH= line in /etc/environment and add it. You can back up that file with sudo cp /etc/environment /etc/environment.old and edit it with gksudo gedit /etc/environment. Then log out and back in.
I'm suggesting changing environment variables systemwide because putting the symbolic link in /usr/local/bin applies to the whole system. And I'm suggesting this way because you seem to be expressing a preference for changing these commands for your whole system. I wouldn't recommend a systemwide change in environment variables if you were putting the symlink in ~/bin. See below if you're interested in that option.

Alternative: Make the Symbolic Link in ~/bin
In Ubuntu, the default .profile file placed in each user's home folder contains:
# set PATH so it includes user's private bin if it exists
if [ -d "$HOME/bin" ] ; then
    PATH="$HOME/bin:$PATH"
fi

You can create ~/bin (~ means "your home directory" and you can use that shorthand when you type commands in the terminal) and log out and back in, and it will be added to $PATH. Executables (and symbolic links to them) placed in ~/bin will then run.
To make your private bin and put an ack symlink to /usr/bin/ack-grep, run:
mkdir ~/bin
cd ~/bin
ln -s /usr/bin/ack-grep ack

In your next login session (and all those after that), you can run ack for ack-grep.


Creating a mixed network. for windows and ubuntu

Install samba

sudo apt-get install samba
sudo apt-get install samba samba-common
sudo apt-get install python-glade2
sudo apt-get install system-config-samba

do a google search on ubuntu to windows share + samba


"Installing fonts on request isn't supported" Error message

This looks like a document that was created with Windows and the fonts are not installed. Try installing the MS-Corefonts:

sudo apt-get install ttf-mscorefonts-installer

That should fix your problem.

There are meta-packages for restricted extras, like codecs and fonts. This depends on your desktop-environment. Choose one of them.

sudo apt-get install ubuntu-restricted-extras   # Gnome based
sudo apt-get install kubuntu-restricted-extras  # KDE
sudo apt-get install lubuntu-restricted-extras  # LXDE
sudo apt-get install xubuntu-restricted-extras  # XFCE


groups: cannot find name for group ID #########

I have a similar issue on a machine I'm provisioning, but I don't yet know how to solve the problem directly, which in my case involves LDAP group enumeration.

However, /etc/bash.bashrc has a configurable flag to disable the section of bashrc that checks to see whether it should remind you how to use sudo.  It is that section of bashrc that calls groups(1), which generates the error you are seeing.

To disable that check, and thus work around this error message, you can:

touch ~/.hushlogin


Running a .sh to execute multiple commands

Simple really - you need to separate the commands. For instance this:

#!/bin/bash
sudo apt-get update
sudo apt-get upgrade

will update the package lists, and then the packages. Another possibility is this (probably better, as the && will only allow the upgrade command to run if the update exits successfully):

#!/bin/bash
sudo apt-get update && sudo apt-get upgrade

This should run the commands for updating the list of packages and then the package themselves. This would need to be saved into a text file (e.g. updatescript in the home directory). You can then make it executable by running:

 chmod +x ./updatescript

or by right clicking on the file and making it executable in its properties:

and run it with this in terminal:

 ./updatescript

Note(s):

There is an option (-y) available that can be used with the upgrade command so it does not prompt before upgrading the packages. It is a good idea to check what apt-get is doing before it upgrades the packages, as it may/will do something stupid or something you don't want it do. More info on options like this can be found by running man apt-get.

This also means it is more ideal to use the terminal to run the script, as you can check what it is updating, and then run it. If you want a GUI way to run the updates, use the software-center as that it is what it is for.


Screen periodically freezing after playing game

swap
Let's increase your /swapfile from 2G to 4G.
Note: Incorrect use of the dd command can cause data loss. Suggest copy/paste.
In the terminal...
sudo swapoff -a           # turn off swap
sudo rm -i /swapfile      # remove old /swapfile

sudo dd if=/dev/zero of=/swapfile bs=1M count=4096

sudo chmod 600 /swapfile  # set proper file protections
sudo mkswap /swapfile     # init /swapfile
sudo swapon /swapfile     # turn on swap
free -h                   # confirm 16G RAM and 4G swap

Confirm this /swapfile line at the end of /etc/fstab... and confirm no other “swap” lines...
To edit, use sudo -H gedit /etc/fstab or sudo pico /etc/fstab
/swapfile  none  swap  sw  0  0

reboot                    # reboot and verify operation

BIOS
ASRock b550m-itx/ac
You have BIOS 1.00.
There's a newer BIOS available, version 1.31, dated 11/6/2020, and can be downloaded here.
Note: Verify that I've got the correct web page for your model #.
Note: Have good backups before updating the BIOS.
memory
Ryzen processors are notorious for memory compatibility issues.
Determine which Ryzen processor family you have here.
Determine if your memory is supported here and here. These are processor family specific lists.
Go to https://www.memtest86.com/ and download/run their free memtest to test your memory. Get at least one complete pass of all the 4/4 tests to confirm good memory. This may take many hours to complete.


Can you suggest any tool for automated crop/rotate of multiple images on scanned on A4 pages?

For quite some time I'm using Gimp with this script.


How do you execute software that needs root access?

Firstly, I am assuming that the motivation of your question is to install packages, so correct me if I'm wrong.

To run commands a root, you can either execute the commands as the root user, or you can append sudo to the beginning of the command. For most applications, using sudo is safer that being root because, among other things, it will force you to make sure that you know what you're doing.

To become root, you can use sudo -i as Michael has commented below, but that shouldn't be necessary to install Google Chrome. To do this, you can simply enter

sudo apt-get install google-chrome

into the command line, but if I understand correctly, you either don't have the password or something is messed up that prevents you from using sudo.

Since you just got Ubuntu, and presumably haven't made any significant changes, you could try reinstalling from the live CD/USB. During the process, there is a prompt to set a password for the account, which you should definitely do -- this will be the password that you will use when using sudo. No doubt, this will be the easiest way to set up an admin account.

If that doesn't work for some reason, or if you are don't want to reinstall, you will probably have to provide more information to get decent answers. You should be able to see what type of account you have (admin or not), and that will tell you if you have sudo permission in the first place.


vmware workstation 10.0 installation on ubuntu 14.0.4

Thanks budiap for posting patch for Workstation 10! It just took me a while to figure out that you need to use that code to apply that code to a patch file. Here is the post I made to vmware workstation forums.

OKAY! I got it. Workstation 10 on Ubuntu15.04, or whatever-buntu. I tested this on Xubuntu 15.04 Kernel 3.19.0-18-generic

Created new pastie(10215458) for patch for Workstation 10.

After fresh install of Workstation 10.06 Specifically - > VMware-Workstation-Full-10.0.6-2700073.x86_64.bundle

Must be root, but you can basically copy/paste.

curl http://pastie.org/pastes/10215458/download -o /tmp/vmnet-3.19.patch_ws10

cd /usr/lib/vmware/modules/source
tar -xf vmnet.tar
patch -p0 -i /tmp/vmnet-3.19.patch_ws10
mv vmnet.tar vmnet.tar.SAVED
tar -cf vmnet.tar vmnet-only
rm -r vmnet-only
vmware-modconfig --console --install-all


Unity support for multitouch screens and touchpad laptop convertibles?

Don't mean to earn any reputation. But the multitouchscreen is supported out of the box. The application lack multitouchscreen support but that is not really a fault of Ubuntu but more like a lack of interest in the community. It has been always a rare amount of people using touchscreen devices on a normal desktop. Most people use Android or Ubuntu Touch instead. Also most touchscreens are glare.

There are even two application for adding multitouch support on applications that do not support it very well.

1) Easystroke - requires mtrack to work with Multitouch. Very good if you do not want to use standard strokes but define them all by yourself. But seems to require a patch to work with mtrack.

2) Touchegg: UI for configuration has to be downloaded and installed separately). For starters the superior option (you mentioned it yourself)

Concerning Wayland / Mir I really have not looked into this concerning multitouchscreens but it*s supported too.

Start looking for Qt/QML-based apps. They are most likely to have Multitouch support.


Fresh Ubuntu install mouse clicks only work once

try to update your ubuntu with this commande "apt-get upgrade"
but i recommand you to fully upgrade your ubuntu  "apt-get full-upgrade"
(if that dosen't work try to use the Software updater but only after upgrading)


SSH to host#1 and then ssh to host#2 from host#1 and then run command and then stay connected

Instead of tmux or screen as suggested by @heemayl, one can also use bash:

ssh host1 -t "command; ssh user@host2 -t 'command; cd /some/path/; bash'"


The reason you can't do this natively with tools built in to Windows is because if you installed the default options of Ubuntu then your partition is formatted in the EXT4 format.  Windows can't read EXT4, but there are tools which can.

Ext2Read is a pretty good tool to use.  It has helped me grab files off a non-bootable linux partition in the past. http://sourceforge.net/projects/ext2read/


type
fsck /dev/sda2
and press enter whenever the terminal asks for input.

Now after the process finishes, type: reboot

After rebooting, open the terminal. Make sure you have internet connectivity and type:
sudo apt-get clean
sudo apt-get update
sudo apt-get updrade

Now, your system will start normally from now on.


How to make remote desktops (Citrix) with resolutions above the native resolution work with Ubuntu?

The HP Pavilion 15-g009AX (G8D85PA) seems to ship with a built in display/panel with 1366x768 pixels native resolution. It wouldn't make sense to try forcing it into outputting a higher resolution. It would either fail to display anything at all or resize and make the image appear blurry.

If you really need a higher resolution to be able to work with your corporate desktop, you should attach an external monitor with a higher native resolution, as already suggested.
Alternatively – or better said, try this first – you should try to set the display size/resolution for this remote connection as described in the product documentation. As Citrix solutions usually use ICA files – which are just plain text files – you can edit a copy of the ICA file and enter a custom resolution that fits your screen. I don't remember the exact lines, but looking at some forum posts, you should look for something similar to this:

DesiredHRES=1024
DesiredVRES=768

This is usually not a big deal and as far as I can remember you can use any display size and aspect ratio, the same goes for RDP connections.

If you use a way of connecting to the remote desktop where you don't/shouldn't have access to the ICA file, you should file a request to whoever is in charge of this system to be provided with an option that works with your screen size or file a request to get a device that works with the current setup.

(Or replace the panel yourself with another that has a higher native resolution and matches your laptop model, which may also require replacing the internal display cable and probably access to HP support technician tools – that you can find online – to remove firmware warnings about changed hardware.)


How do I simulate removal of the LAMP server on Ubuntu 16.04?

A good way to do this is using the aptitude package manager. It's an advanced package manager that even includes an in terminal graphic display. Install it with

apt-get install aptitude

Now you can simply use simulate function with

aptitude -s purge phpmyadmin php5 mysql-server

(This command is only to show you how it works! I don't know which packages you exactly want to purge so add them yourself)

However this only shows what will be purged, not the actual purging(like @Rinzwind stated.


ubuntu 14.04 wont play amazon prime videos in fierfox anymore

It Looks like they want html5 player and that  is not available for firefox:


How to NOT become a root user? Are administrators root?

You are an administrator, but not root. The root user can do anything. Administrators can perform actions as root, but ordinarily what administrators do is not done by root. That way, you have full control over your own system, but only when you choose to use it.

Ubuntu asks for your password when you try to do stuff as root, to make sure it's really you.

User Accounts: Human, and Otherwise

Real human users have user accounts to represent them. You created one such account when you installed Ubuntu. But not all user accounts represent real human users.

Real human users are granted (and denied) abilities through their user accounts. They must use their user accounts to use the system; therefore, their user accounts' abilities and limitations apply to them.

User accounts are also used to codify sets of abilities and limitations. Some user accounts--most, actually, unless you have many human users of the machine--exist so that certain programs or commands can be run with their identity, an identity with the right abilities and limitations for the job.

For example, the www-data user exists so that if you run a web server, it owns the data the server make accessible. No real human user has to be empowered to make unchecked changes to those data, and the web server doesn't have to be empowered to perform any action unnecessary for serving the web. Consequently, both the web data and the rest of the system are more secure against accidental or intentional breakage, than if the web server were run by some human user who would have all the powers of the web server (and whose powers the web server would possess).

The Most Important Non-Human User Account

The superuser, whose username is root, is a non-human user account with a very specific combination of abilities and limitations: all abilities, and no limitations.

root's allowed to do anything. There are still things root cannot do because the system itself cannot perform or make sense out of them. So root cannot kill a process that is in uninterruptible sleep, or make a rock too heavy to move, then move it.

Many important system processes, like init, run as root, and root is used for performing administrative tasks.

Can I log in as root?

It's possible to configure the root account so it's possible to log in with a password, but this is not enabled by default in Ubuntu. Instead, you can think of root as being like www-data, lp, nobody, and other non-human accounts. (Run cat /etc/passwd or getent passwd to see them all.)

Human users log in with their own user accounts, and then if some task is to be performed with another user account, they cause that task to be performed with that identity, without actually having logged in as that user.

It's possible to configure the other non-human users, like www-data, so one can log in as them, too. That's quite rare, though, whereas in some other Unix-like OSes it's common to log in as root in a terminal. The risks of running a whole graphical interface as root, combined with how many graphical programs are not designed to run as root and may not work properly, mean that you should never attempt to get a root-owned desktop session.

Please note that while logging in as root is disabled by default in Ubuntu, there are ways to get a root shell without authenticating as root, which produce a similar effect: the most common are sudo -s or -i, recovery mode and similar techniques. (Don't worry if you don't know what those things are.) This is not actually logging in: in recovery mode, you become root before any login would occur; with the sudo-based methods, you're just running a shell as root.

Administrators

In Ubuntu, administrators are the users who can do whatever they want as root, when they choose to do so.

System Settings > User Accounts. "Eliah Kagan" is an administrator, so he can do stuff as root, but he is not root.

I'm an administrator on my Ubuntu system. When I run programs, ordinarily they run as ek ("Eliah Kagan" is the full name that corresponds to the ek username.)

When I run AbiWord or LibreOffice, it runs as ek. When I run Firefox, Chromium, Empathy, or Pidgin, it runs as ek. The programs that run to provide the desktop interface run as ek.

However, I am an administrator, so if I need to perform an administrative task, I can do so.

sudo

On the command line, I would ordinarily use sudo to run a command as root:

sudo command...

This will prompt me for my password. (Not root's password; root does not have one.)

Because I am an administrator, I can perform actions as root. In the default configuration, I must enter my password to do this.
Users who are not administrators cannot perform actions as root, even by putting in their password. sudo commands will fail if the user running them is not an administrator.

Because administrators are perfectly ordinary users except for the ability to perform actions as root, running a command requiring root privileges will still fail, except when the command is run as root.

Screenshot illustrating the need to use sudo to perform administrative tasks. (Based on "Sandwich" by Randall Munroe.)

sudo, Graphically

Graphical programs can run as root through graphical frontends for sudo, such as gksu/gksudo and kdesudo. For example, to run GParted as root I could run gksudo gparted. Then I would be prompted graphically for my password.

Since I'm prompted graphically, there doesn't have to be a terminal. This is one of the ways administrative tools are run as root.

Polkit

Polkit (once known as PolicyKit) is another way for administrators to do things as root. A program accesses a service that performs the action. Sometimes, the action is running a whole program; sometimes the action is more limited.

These days, many graphical system administration utilities are set up to use polkit by default, rather than to use sudo.

One example of such a utility is the Software Center. It takes full advantage of polkit, requiring the user to put in their password only when they want to do something that requires root privileges. (This is possible with sudo-based authentication also, but it is harder and uglier to accomplish.)

In the Software Center, I can find and read about an application; then I'm asked for my password when I want to install it.

How polkit Is Different

Any graphical program can be run as root with gksudo and other graphical sudo frontends. (The program might not work very well, depending on whether or not it's designed to be used as root. But the command to start the program will be executed as root.)

While polkit is now more common than sudo GUI frontends as the way applications on Ubuntu perform actions as root behind the scenes, polki will only run a graphical application as root if there is a configuration file allowing it and indicating what actions may be performed.

Polkit, Non-Graphically

pkexec is the command used to run a program with polkit.

Like sudo, pkexec can run non-graphical commands. (And it does not require a configuration file defining the command's capabilities--it simply runs the command as root.)

pkexec command...

pkexec prompts for a password graphically, even if it is run from a Terminal (this is one of the ways its behavior is more similar to gksudo than to running straight sudo).

(If there is no GUI--for example, if you're logged in from a virtual console or text-only SSH session, or the GUI is not functioning properly--then pkexec will degrade gracefully and prompt for your password on the command line.)

Once authentication is performed successfully, the command runs in the terminal.

Running Commands as Other Users Besides root

root is special because it gets to do anything that can be done. But it's a user account like any account, and the ways of running commands as root with sudo (directly or with a graphical frontend) or polkit can be modified slightly to run a command as any other user:

sudo -u username command...

gksudo -u username command...

pkexec --user username command...

What? You just type sudo first? How is that security?!

Running commands with sudo is sort of like invoking papal infalliblity.

When you run a command with sudo [invoke papal infallibility], Ubuntu [Catholic folks] tries hard to make sure you're really you [really the Pope].

Yes, I know papal infallibility (even when normative) is declarative; the parallel is not perfect.

Trying to do something as root with sudo (or polkit) is a big deal--Ubuntu is not just going to let that slide by like all the other times you run a program.

You are prompted for your password. (Then, that you have done so is remembered for a short time, so you don't have to constantly enter your password as you administer your system.)

Besides reminding you to be careful, this safeguards against two scenarios:

Someone uses your computer (or mobile device), maybe under the guise of checking their email or some similar innocuous purpose. Here, it's still possible for them to do some harm--for example, they could modify or delete your documents. However, they cannot administer the system, since they cannot put in your password.
Programs that aren't supposed to administer the system cannot do so, unless you enter your password. For example, if your web browser is compromised by a security bug and runs malicious code, it still cannot perform administrative tasks. It cannot create and delete users, modify programs installed as root (which includes anything installed by the package manager, such as LibreOffice), or alter the system at a deep level.

I've heard of su. What's that? Can I use that?

su authenticates as another user, and runs a command (or starts an interactive shell). It's possible to limit who is permitted to use su, but su authenticates with the target account's password, not the password of the user running.

For example, su username -c 'command...' runs command... as username, just like sudo -u username command....

But when you run a command as username with sudo, you enter your password. When you run a command as username with su, you enter username's password.

Since su performs authentication for the target user, with su you can only run commands as users whose accounts are enabled.

The root account (like www-data and nobody) is disabled by default. There is no password that will work to log in as root. So you cannot use su to run commands as root.

You can use su to run commands as another user who can log in (which typically includes all the user accounts on your system that represent human beings).

When logged in as a guest, you cannot use su at all.

Combining su and sudo

Someone who is not an administrator can even use su to run sudo as an administrator. (This is OK though, as they need the administrator's password to run commands as the administrator.) That is, a limited user can use su to run sudo to run a command as root. This can look like:

su username -c 'sudo command...'

(Running graphical programs this way requires special care.)

Wouldn't su be a more secure way to run commands as root?

Probably not.

What if a user shouldn't be allowed to act as root?

Make them a limited user instead of an administrator.

What if a program running as an administrator tries to sudo to root?

Unless you have reconfigured sudo to let it succeed without a password, it will fail.

Can't a program that shouldn't be run as root piggyback on a recent sudo command, so no password is required?

This would be very unlikely to succeed. These days, most operating systems (including Ubuntu) have sudo configured by default so that its timestamps apply only in a specific context.

For example, if I run sudo ... in one Terminal tab and authenticate successfully, sudo in another tab (or run by an unrelated GUI program, or that I run from a virtual console or SSH session) will still prompt for a password. Even if it's run immediately afterwards.

Doesn't a program running as user X have access to user X's password?

No.

If a malicious program is able to run as an administrator, can't it "listen in" to what's being typed when the administrator authenticates with sudo or polkit?

Potentially, yes. But then it could "listen in" to a password typed in for su.

If I tell someone my password—

Don't tell people your password.

What if someone has to know my password to do something on my behalf, but I don't want to let them administer the system?

Ideally, they should have a separate user account that lets them do what they need to do. For example, can share files between accounts, allowing multiple user to write to them, while still denying access to other users.

However, in a situation where a less-trusted person may be permitted to share your account, it should be a limited user account. You could make a separate account for this purpose (which makes sense--if it's an account for you and someone else who you want to have different capabilities, it should be a different account).

So, would the most secure thing be to disallow both sudo and su and make people log in as root, manually?

No, because there are serious disadvantages associated with letting people log in as root at all. Whenever possible, the smallest number of actions as possible should be undertaken as root. Even most acts relating directly to administering a system (e.g., looking at what users are configured, and reading logs) usually don't require root privileges.

Also, just as potentially a malicious program could watch what someone types when they run sudo or su, or create a fake sudo/su password prompt, potentially a malicious program could create a fake login screen, too.

What makes a user an administrator?

Group membership.

In Ubuntu 12.04 and later, administrators are members of the group called sudo.

In Ubuntu 11.10 and earlier, administrators are members of the group called admin.

When an Ubuntu system before 12.04 is upgraded to 12.04 or later, the admin group is kept for backward compatibility (and continues to confer administrative power to users in it), but the sudo group is used as well.

Limited User Accounts

Can I use a limited user account instead of an administrator account?

If you like, sure. Create a limited user account in System Settings > User Accounts, and log in as that user.

Can I make my administrator account a limited user account?

Yes, just remove it from the sudo and admin groups (see above).

But you should make sure there is at least one other administrator account, so you can administer your system. If there is not, then you'd have to boot to recovery mode or a live CD and make some user an administrator again. (This is similar to resetting a lost administrator password.)

Graphical tools for administering users and groups will usually keep you from creating a system with no administrators, or at least warn you. Command line tools typically will not (trusting that you know what you're doing).


Where can I find log of System program problem?

To view different types of logs, for like troubleshooting purposes the best way is to use Log File Viewer which is a GUI interface, that can be used to view different types of logs.

In your case particular open this Log File Viewer and then you will get an option stating syslog then double click on this option to view syslogs.

To troubleshoot your problem if this problem arises during startup of your system, Restart your system then view the logs for error messages. (You can take hint from the date and time stamp recorded in the log files.)

Or you can also use the tail command to view logs.

tail -f /var/log/syslog

-f : it will show logs which are dynamically added later on.

or to view a number of logs use:

tail -n 100 -f /var/log/syslog

-n : number of lines to display (In the above case it's 100.)


You can easily install comix via software center (or by clicking here) that way it is automatically added to your gnome menus and updated via the update manager.


updated chrome, now pipelight not working

Latest Chrome has dropped support for the old plugin APIs (see http://blog.chromium.org/2013/09/saying-goodbye-to-our-old-friend-npapi.html).

Therefore any plugins that use such an API will not work anymore on latest Chrome browser for Ubuntu. They will work however ok in Firefox.

It may take some time until developer can respond to that situation and create compatible plugins, if ever.


How to group fields having same data using basic command

Assuming that those fields are stored in a file, let's call it 'file.txt', you can use the following command:

cat file.txt | awk -F":" '{print $3}' | sort | uniq -c | awk '{print $2" "$1}'


What should my swap size be if I have 32GB of RAM?

If you want hibernation to work, it has to save everything in RAM to swap space so that it can be restored when the computer is turned on again, so you'd need at least 32 GB of swap space.

If you don't care about hibernation, unless you plan to use more than 32 GB on a regular basis, a small amount like 4 GB or 8 GB would be fine for now. Swap space can be resized later.


How can I collaps the icons of running applications?

Right click the task manager (where all those icons are), and pick "Task Manager Settings".

Under "Grouping and Sorting" you'll be able to pick a behaviour that fits your flow.


Can I use a kernel package from another distro?

In general, the answer is "yes". You can always install an alternative kernel without breaking anything in your system. And since you can have multiple kernel alternatives that can be selected at boot time, you don't risk much: if your new kernel is not really working well with Ubuntu, you can always boot the system using the previous kernel.

However, the particular repository and package you mention are tailored to be used with the Archlinux distro. What that means is that while you can most likely use the tailored kernel with your Ubuntu system, you will run into problems when trying to install this kernel as a package, because Archlinux uses a different packaging system. I would not try to install that particular kernel package without understanding pacman.

Probably the best solution would then be to use the git archive (mentioned at the kernel-eee Archlinux page) to copy the package sources to your computer, and then compile and install the kernel manually. This is actually easier than it sounds, but nonetheless requires some skill and reading. Nothing for you if you just "want it to work".

Alternatively, google for "eeepc kernel Ubuntu", maybe there are packages already compiled for Ubuntu.


Simply use crontab, instead of using a time intervall simply say @reboot

So login as the user who should start this script and type the command

crontab -e

and then enter

@reboot /better/enter/fullpath/here/docker-compose -f /usr/bin/myapp/docker-compose.yml -p myapp start

Reboot the system and see if it works. There's one advantage over upstart, even it it is started a little bit later, you don't have to worry much about dependcies like networking, etc. to be up already.


Ubuntu 18.04 Gnome blank file and directory icons

Running the following commands fixed the issues, though I'm not sure if both are needed or if it's only one of them:

gsettings reset org.gnome.desktop.interface gtk-theme
gsettings reset org.gnome.desktop.interface icon-theme

This didn't change anything else other than restoring the icons, probably due to the fact that I never changed the theme to begin with – so I have to assume that some of the settings on my machine were badly configured and this reset them back to their defaults.


Where can I find more documentation on building an Ubuntu-based cloud infrastructure?

Actually, I'm in the process of doing what you are talking about right now.
I have a small cluster at home that I am learning to deploy these technologies on.

All of these tools are changing VERY RAPIDLY in my opinion.

Two months ago, I started learning Orchestra. Last week I was posting here, and found out that Orchestra has been deprecated. Now MaaS on 12.04 is the way to go, and so far it has been just as rococo as Orchestra was.

Its hard to find documentation from people that are doing it. That is why I am posting alot of questions here.

I did find the MaaS wiki pages, which are helpful: https://wiki.ubuntu.com/ServerTeam/MAAS

Maybe this helps you get started.


Try to reinstall the indicator applet.

sudo apt-get install indicator-applet-complete


Install Ruby 2.0 with OpenSSL and ReadLine support

In your source location, cd ext/openssl and then ruby extconf.rb.  This will generate a makefile in the ext/openssl directory.  Simply make && sudo make install it to build the ruby openssl extension, and install the .so into the appropriate location.

Ditto ext/readline for readline support.

Then you should be able to make ruby properly.

Edit: in case I wasn't clear enough:

pushd ext/openssl
ruby extconf.rb
make && sudo make install
popd

pushd ext/readline
ruby extconf.rb
make && sudo make install
popd

make
sudo make install


Is it possible to enter password for sudo only once, and configure it to not require for password on other terminals?

Sure it is. Run sudo visudo and add this line to your sudoers file:

Defaults        !tty_tickets

As explained in man sudoers:

 tty_tickets       If set, users must authenticate on a per-tty basis.
                   With this flag enabled, sudo will use a separate record
                   in the time stamp file for each tty.  If disabled, a
                   single record is used for all login sessions.  This
                   flag is on by default.

By setting tty_tickets to off (that's what the ! means), you enable a single authentication to be shared by multiple sessions.


After creating partitions on the disk in question you need to format the partitions to the desired form using the commands below after first quiting from parted:

sudo mkfs -t ext3 /dev/sdb1
sudo mkfs -t ext4 /dev/sdb2


System settings application crippled in i3

You should try to declare environment variable with GNOME desktop and launch GNOME Control Center with it:

env XDG_CURRENT_DESKTOP=GNOME gnome-control-center


Is there a way to disable laptop LCD on startup when external monitor is connected

After hacking away at it, I finally got it to work.. I was never able to get this to execute from LightDM but adding the sleep option and adding it to startup applications worked

#!/bin/bash
sleep 5
XRANDRexternal="xrandr --output HDMI1 --off --output LVDS1 --off --output DP1 --mode 2560x1600 --pos 0x0 --rotate normal --output VGA1 --off"
XRANDRnoexternal="xrandr --output HDMI1 --off --output LVDS1 --mode 1280x800 --pos 0x0 --rotate normal --output DP1 --off --output VGA1 --off"
if xrandr | grep -q ' connected'
then
${XRANDRexternal}
else
${XRANDRnoexternal}
fi


Remote Ubuntu Desktop 17.10, how to access it with ssh and GUI

You need to install VNC to make GUI connection easily from Windows and Mac even another Linux machine
check this tutorial for more help
How to Install and Configure VNC on Ubuntu

same way to install it on 17.10


Ubuntu 18.04.1 repositores are not working

The core issue is that the Mirror in use by the ir.archive.ubuntu.com DNS Round Robin that you landed on is not working properly.

About 2 minutes ago relative to this post,  the notification of this mirror timing out to the Ubuntu Mirrors team (part of Canonical's Systems Administration teams) indicating that they have, for now, removed the IP from the round robin rotation due to the timeouts (for now).


Unable to run Ubuntu 14.04 LTS in live environment: "processer context corrupt"

That definitely looks like a hardware issue, and is somewhat unrelated to Linux. As your machine looks to be several years old, it could most likely be a problem with the power supply or the mainboard (capacitors are prone to fail after a while). If you have a spare power supply, I would recommend you try replacing your power supply with that.

It might also be related to the memory, or the BIOS. In How to diagnose and fix Kernel Panic Fatal Machine Check error?, the problem was fixed by switching the BIOS boot mode to UEFI OS from UEFI and CSM OS. I would try that suggestion first.


For resetting to Out Of Box performance you DO NOT want to use the "write zeroes" technique of dd/fio. There is a BIG semantic difference saying "this area must contain and maintain zeroes" (fio/dd technique) and saying "this area is must be empty" (secure erase). For example the Solid State Storage (SSS) Performance Test Specification (PTS) specifies techniques it considers reasonable for preconditioning.


do-release-upgrade is the command-line equivalent...

... but if you're upgrading from 10.10 (as the screenshot suggests), you might do best to just reinstall 12.04.5 or 14.04. You'll save a ton of bandwidth and it'll almost certainly take less time.


Need help building shell script for copying

What you need is a single command: rsync

To do the very fist copy do a:

cd path/to/local/directory
rsync --verbose --recursive --progress /path/to/cloud

Whenever you get disconnected or want to update, just do a:

cd path/to/local/directory
rsync --verbose --recursive --progress --update /path/to/cloud

For more bells and whistles: man page here.


Dual Boot - Booting Ubuntu brings me to Grub Command Line - New User

You say you have windows 10 On your computer If I understand you,you also want to install ubuntu 16.04 on a partition and had it on once.
In windows 10 open the control panel click on Administrative tools on that window click computer management once in there click disc management. If you don't see it,click arrow infront of storage,once you see it  click disk management.Wait for your drive to show Part C: should be your windows 10 the partition you want Ubuntu to go should be re formated as to make it clean for installing your Ubuntu. If thats not right let us know.If you have installed Ubuntu 16.04 to a second drive reformat it then try a clean reinstall.


How to differentiate between Qt4.8 and Qt5.8.7

I think you may be confusing Qt (a software development framework) with Qt Creator (an Integrated Development Environment (IDE)). Qt Creator is the default IDE for Qt, however it isn't the only IDE that can be used and doesn't have anything to do with the version of the Qt framework you are using in your own development.

When you install using the online installer, the default installation will install the latest version of the Qt framework and the latest version of Qt Creator. During this installation process, you are able to select additional Qt framework versions to install, if required. For example, you could install 5.3 and 5.8. In all the installations I've performed, a maintenance tool is also installed. This can be used at any time to add/remove/update the installed components (i.e. you could launch this after installation and add Qt 5.6 to the above). The maintenance tool is located at {installation folder}/Qt.

A single installation of Qt Creator can be aware of a number of different Qt versions at the same time. You configure which version it should use within each of your projects. You can view the Qt versions that Qt Creator "knows about" by selecting Tools->Options from the menu and then selecting the Build & Run option and then the Qt Versions tab. The Qt Creator that you installed using the online installer will automatically detect the versions of Qt you installed during the installation process. However, different Qt versions can also be added manually from within the same dialog.

Hope the above helps. In summary:

You do not need to install more than one copy of Qt Creator. If you are installing using the online installer, I would recommend running the online installer using sudo and installing to /opt/.
To open the Qt Creator you have installed using the online installer, you would need to browse to {installation folder}/Qt/Tools/QtCreator/bin and then ./qtcreator. You should not need to launch this using sudo. You should also be able to launch it from the launcher or menu of your desktop.
To set the version(s) of the Qt framework in use for a particular project, click the project button and select/configure the versions as required.
The reason Qt Creator states "based on Qt 5.5.1" is because that particular version of Qt Creator was built using the Qt framework version 5.5.1.
I think Qt has some good documentation including guides, examples etc. This is available here.


I had tried re-installing Thunderbird,but the search still failed. Shortly after posting this question, I restarted the machine and all is back to normal again.


You can mount the casper-rw file, (and in your case the casper-rw-old file).

First CD to the location where the casper-rw files are located.

(in my case this was cd /media/cscameron/LIVE-LINUX)

Then make a directory to mount casper-rw-old in:

sudo mkdir /media/casper-old

Then mount it:

sudo mount -o loop casper-rw-old /media/casper-old/

Make another directory for casper-rw

sudo mkdir /media/casper

Mount casper-rw

sudo mount -o loop casper-rw /media/casper/

And copy all of the files from the casper-rw-old file to the mounted blank casper-rw file

I am not quite sure how this differs from what you did, perhaps cd'ing to media rather than to cdrom.
I am doing this while booted from internal drive, (or Live DVD), not from the persistent USB.


Double clicking delay too short on 20.04

Gu to Settings → Universal Access → Double-Click Delay
Reduce the value of Double-click delay according to your convenience and check whether the mouse Double-click is working or not. Continue this action till you are able to perform double-click.


How to Optimise SSD to increase lifetime?

TRIM function for SSD has been enabled by default since Ubuntu 14.04. This is the major function to help increase the performance and life of your disk.

So, short answer is yes it is optimized, since TRIM is the major function you should worry about. Although you can always check another settings, see link below.

TRIM enables an operating system to notify the SSD of pages which no longer contain valid data. For a file deletion operation, the operating system will mark the files sectors as free for new data, then send a TRIM command to the SSD. After trimming, the SSD will not preserve any contents of the block when writing new data to a page of flash memory, resulting in less write amplification (fewer writes), higher write throughput (no need for a read-erase-modify sequence), thus increasing drive life.

Reference:

Trim- Wikipedia
How to optimize your Solid State Drive for Linux Mint 18.1, Ubuntu 16.04 and Debian


How to resolve wireless soft blocking permanently

Please open a terminal and do:

gksudo gedit /etc/rc.local

Right above the line exit 0, add a single line:

rfkill unblock all

Proofread carefully, save and close gedit. You should be all set.


unable to upgrade to lts (or any supported distro) I am new no dvd

This might be of some help to you if you have a floppy drive.


I do not see my pen drive in the system after I have formatted it

Unplug it and plug it back in.

When you perform formatting, the device is unmounted and will remain unmounted until you unplug the device and then plug it back in.


You can edit the rc.local file to auto start lampp.

use root login and edit /etc/rc.local file and add line /opt/lampp/lampp start to end of the file.

Reboot the machine and you can check the status of the lampp using /opt/lampp/lampp status

Hope this helps you!


You can try this:

Open xfce4-session-settings and activate this option:

More options which could be useful in this case you will find in the light-locker-settings menu:

You can completely disable auto logging out if you disable light-locker.


How to uninstall Android Studio completely from Ubuntu?

If you installed it from Android website, then do rm -r the directory into which you extracted the android-studio-ide-141.1890965-linux.zip file.

Also remove .AndroidStudioPreview (or .AndroidStudio1.3 etc., depending on version) which generally resides in your home directory (/home/your-username/).

If you see the android-studio folder in your /home/user-name/android-studio, remove that too.


How to cat the `MAAS Key` of a user via `maas shell`?

maas shell

>>> from apiclient.creds import convert_tuple_to_string
>>> from django.contrib.auth.models import User
>>> from maasserver.models.user import get_creds_tuple
>>> admin = User.objects.get(username='admin')
>>> token = admin.tokens.all()[0]
>>> print convert_tuple_to_string(get_creds_tuple(token))


Messaging Menu missing after upgrade to 12.10

The way applications interact with the messaging menu was changed in 12.10, and not all applications have been updated. Pidgin (as of 20th Oct 2012) has not been updated. There is a ticket tracking what applications have been migrated. Until then Empathy could be used as an replacement.


opening a very long url in tmux terminal

It actually depends on how exactly your URLs appears on the screen.

If you just print out the lines as it naturally happens (e.g. with cat command), the lines get joined and the URLs can actually be clicked.

However, if you use vim or less or another viewer, they try to show the text line by line and it's actually the software to break the lines.

With less, the action that helps is: scroll back one screen with b and forward with space.

With vim something like :w !cat can help.

In other words, you should think of a way to just naturally print the URL so that it would wrap over the screen border.

Needless to say, your screen should occupy the full terminal width, i.e. not split vertically.

To temporary remove all other panes, there's 'zoom' for panes in tmux: activated by C-b z.


Problem connecting to Android wireless tether

I used the Hotspot Mobile app by Motorola and with that I could connect to the Android wireless tether using Ubuntu. You have to configure the Hotspot Mobile app preferably setting a password and Ubuntu will recognize it immediately and let you connect. I used Defy with Android 2.2 and Ubuntu 11.10. If you still have problems, here is the Ubuntu official guide on connecting to ad-hoc networks.


Why do some things always show up in the HUD when using other applications, but not others

For HUD, the rule seems to be, you can do something with only those things that you can see.

You can ALWAYS see app-indicators, so all menu items related to these are always available.

But for other applications, the menu items are available only when you are 'in' that application.


Execute a desktop shortcut to a jar file on Ubuntu 18.04

Defining Path might help. The following works for me:

#!/usr/bin/env xdg-open
[Desktop Entry]
Version=1.0
Type=Application
Terminal=false
Exec=java -jar '/home/cenap/someprogram.jar'
Path=/home/cenap/
Name=SomeProgram
Comment=SomeProgram
Icon=/home/cenap/SomeProgram-icon.png


Using AMD graphics card with Ubuntu (Sound)

The sound device on your HDMI should appear the same whether you use Proprietary (fglrx) or Open Source (Mesa) drivers.

On AMD cards it is run through the ALSA drivers, and is on a separate PCI sub-device as far as software is concerned.

You probably simply do not have it set as your default sound output.   You should be able to do this in the appropriate audio settings for your desktop environment(s).


Reverting swapping CTRL and CAPS key is not persistent

Use this command to reset the behavior:

gsettings reset org.gnome.desktop.input-sources xkb-options

and remove the setxkbdmap-thing in your .profile


How to create a bootable USB stick that really works?

The Ubuntu Startup Disk Creator in 14.04 LTS is buggy, and you are affected by a known bug, that is squashed by re-writing the Startup Disk Creator (from an extracting tool) to a robust cloning tool in Ubuntu 16.04 LTS (and newer versions).

I suggest that you use another tool, for example mkusb according to the following links.

help.ubuntu.com/community/mkusb

help.ubuntu.com/community/mkusb/persistent

If you run standard Ubuntu live, you need an extra instruction to get the repository Universe. (Kubuntu, Lubuntu ... Xubuntu have the repository Universe activated automatically.)

sudo add-apt-repository universe  # only for standard Ubuntu

sudo add-apt-repository ppa:mkusb/ppa  # and press Enter
sudo apt-get update
sudo apt-get install mkusb mkusb-nox usb-pack-efi

The following links explain what is happening, when you create a USB boot drive, and describe some tools.

Having trouble booting from flash drive

help.ubuntu.com/community/Installation/iso2usb


Okay, found the answer. For anyone that might have this issue.

When I've installed Ubuntu, RST is not supported so I had to switch to AHCI.
Windows won't boot in AHCI, it would just load the recovery mode.
After going back in the UEFI and switch it back to RST premium, both Windows and Ubuntu boot normally.


Seems you're using the Installer for Ubuntu 19.04 (which is End of Life) to do the job, that's the culprit.

According to https://launchpad.net/~yannubuntu/+archive/ubuntu/boot-repair
no packages are provided for disco (19.04).

You'll need to download a recent version of Ubuntu from https://ubuntu.com/#download and create a new installer USB.


How to uninstall a python package that I installed after compiling it with bazel?

Bazel is only used for building Tensorflow; the actual installation is done with pip. So you need to uninstall it via pip as well.

If you installed two versions of Python to /usr/local, it's possible that the second installation overwrote the /usr/local/bin/pip command from the first. So you no longer have a pip command for the first version. However, the command is just a wrapper, and you can use Python directly to run the pip module, which functions just like the pip command:

python3.5 -m pip ...

With this you can install/remove packages for that version of Python.

However, for the future, I strongly recommend using virtual environments (via pipenv or anaconda, etc.) instead of installing to /usr/local, for better isolation. Installing to /usr/local also typically requires root, and it's a security risk to run arbitrary scripts downloaded from the internet as root (which is essentially what pip does with setup.py).


By delete did you mean from the GUI file browser or rm -rf from the console? If it's the former than all those files are in the trash and you need to empty it to reclaim the space. The build is self-contained, if you truly wiped out the git/build tree then everything associated with the build is gone.

This is the procedure I use to build kernels:

https://wiki.ubuntu.com/Kernel/Dev/QuickBuildLocal

Most users usually don't have a good reason to build their own kernel, unless you're into tweaking that is in which case have a blast :-).


sudo add-apt-repository ppa:hanipouspilot/rtlwifi
sudo apt-get update
sudo apt-get install rtlwifi-new-dkms linux-firmware

this worked on ubuntu 14.06. test it and tell me if it worked for 16.04 too.


How can I get alt-tab to work in VirtualBox VM when in full screen?

Using right Ctrl you can move between real OS and Virtual for the shortcuts. So every time you hit that button, you change between VM and the real machine and there is where the shortcut will apply.

The default desktop that a shortcut applies when you open a VM in full screen is a little bit random. Sometimes inside the VM, sometimes on the real desktop.


/sbin/ldconfig.real: Warning: ignoring configuration file that cannot be opened: /etc/ld.so.conf.d/nvidia_settings.conf

I had a similar warning after upgrading from 16.04 to 18.04

I have removed nvidia-settings.conf from /etc/ld.so.conf.d since it was pointing to files which did not exist. So far so good...


Core i7 with 4GB - go 64 bit or stay 32bit..?

There may well be some annoyances along the way. A few of the proprietary components of Ubuntu (like the Oracle Java runtime and Adobe Flash) might be a bit harder to install that you would expect.

There may also be problems with some obscure wireless drivers and the like - but this is the exception rather than the rule.

Other than that, Linux' great 32 bit compatibility layer ensures that your system will be pretty much rock solid and, often time, quite a bit better at computational task that benefit from the larger address size.

Ubuntu server is now recommended by canonical in its 64 bit form per default. There is, all in all, much trust in the 64 bit linux architecture. It is no longer experimental, it is no longer just an add on. And even though some of the applications haven't caught up (flash is the only one of them that matters, really), the Linux kernel is now considered a 64 bit system with a 32 bit compatibility layer, rather than the other way round.

In short: Do it, go 64 bit - it's running millions and millions of Linux servers today, and it's completely ready for your desktop.

As Huygens points out, 32 bit is the safe bet. If you can stand the potential annoyance of re-installing the 32 bit version, it makes sense to try 64 bit first, and test for common issues.

The 32 bit installer will of course automatically enable a PAE kernel if you have more ram then can be addressed in 32 bits, rendering the ram issue a thing of the past. This has been said many times here, but why not include it again :)


How can I restore a deleted username using its old home folder?

The best option would be indeed to turn the new user into the old user.

Have a look at the /etc/passwd file:

new_user:x:1000:1000:New User,,,:/home/new_user:/bin/bash

Edit this line only as root to:

old_user:x:1000:1000:Old User,,,:/home/old_user:/bin/bash

Then reset the old users password: passwd old_user as root.


When you say you installed alsa, do you mean you installed alsamixer?  If not, install alsamixer, pull it up and check to make sure you microphones aren't muted.

$ sudo apt-get install alsamixer

Assuming alsamixer is ruled out, post up the output of:

$ arecord -l


-bash: ./my_file: cannot execute binary file:Exec format error, but my architecture and elf matches

ELF 32-bit LSB executable, ARM

This is a 32bit ARM executable file designed for the 32-bit ARM infrastructure environments (armhf, armel, arm64 when you have the 32bit ARM libs)

  aarch64

Your architecture is 64-bit ARM.  Specifically, aarch64 chips ONLY support the ARMv8 A64 instruction set, and do not support A/T32 runtime instruction sets like this binary needs 1.

So the system's complaining is actually valid - the 32-bit ARM executable has an invalid ELF header for a 64-bit aarch64 environment which can't execute A/T32 instruction sets.

1  Supposition based upon https://en.wikichip.org/wiki/arm/aarch64 which states:

  The AArch64 execution state was introduced with the ARMv8 ISA for machines executing A64 instructions. A machine in AArch64 can only execute A64 instructions and cannot execute A32 or T32 instructions.


How do I burn a DVD ISO using the terminal?

There are several ways to do this, but here are just two ways that I use regularly. Please replace /dev/sr1 with the device identifier of your target drive (find out what it is with inxi -d), and replace myiso with your iso and its disk location if necessary.

wodim -eject -tao  speed=2 dev=/dev/sr1 -v -data myiso.iso
growisofs -dvd-compat -Z /dev/sr1=myiso.iso

More information about the read and write capabilities of your drive can be found with the following command, again substututing my example /dev with your device identifier:

wodim -prcap dev=/dev/sr1

For more options relating to wodim and growisofs, see their respective manpages, by entering man wodim and man growisofs. (Note: wodim is a fork of the original cdrecord program)


If you're chrooting the users, you should either use ForceCommand internal-sftp or set up a shell (along with everything it needs) in each home directory. If neither of these was done, SSH won't be able to login the user.


Ubuntu 16.04 on OSX with VirtualBox, Unity incredibly slow?

This is most likely caused by the absence of 3D acceleration (settings -> display -> enable 3d acceleration).

Unfortunately, at this time, this option does not work for mac. See this link