Installation of Windows 10 alongside Ubuntu 16.04 LTS (32 bits) (Windows after Ubuntu)

I'm afraid you're heading down a path to frustration, but it's not too late to correct course.

In Brief

If your computer is this one, it looks like it's got a 64-bit CPU and 64-bit EFI. As such, installing a 32-bit Ubuntu (apparently in BIOS/CSM/legacy mode) was a mistake. You're now trying to install (apparently 64-bit) Windows, and the Windows installer is complaining about the MBR partition table, but that's a misleading error message -- it should really be complaining about your boot mode (you've booted in EFI mode, but it needs to be in BIOS mode to be happy).

The Details

Almost all modern computers use EFI (or UEFI, which is EFI 2.x) firmware. This type of firmware replaces the much older and less capable BIOS firmware. Confusingly, many people, and even manufacturers, refer to EFI as "BIOS." This encourages applying BIOS-specific knowledge to EFIs, but doing so usually results in incorrect inferences being drawn. Adding to the confusion is the fact that most EFIs provide a feature called the Compatibility Support Module (CSM), which enables EFI-based computers to launch boot loaders and OSes designed for older BIOS (or "legacy") firmware.

One of the drawbacks to EFI is that it's difficult to boot an OS of a different bit depth than the firmware itself. That is, if you've got a 32-bit EFI, you're limited to running a 32-bit OS; and if you've got a 64-bit EFI, you're limited to running a 64-bit OS. The easiest way around this limit is to enable the CSM and install in BIOS mode. This seems to be what you've done. There are few or no real advantages to running a 32-bit OS on a 64-bit computer, though; in fact, as described by Linus Torvalds himself, 32-bit imposes significant limits once your RAM expands above 1.33 GiB. Thus, the better choice for you would have been to install a 64-bit version of Ubuntu. This would have given you better options today. As it is, you have a number of possible choices, but the two best ones are:

Reconfigure for 64-bit EFI-mode -- You can back up your personal data, delete the existing partitions, disable the CSM, install Windows 64-bit in EFI mode, install Ubuntu 64-bit in EFI mode, and restore your data. In the long term, this is the best solution, but of course you'll need to back up and restore your personal data, do two OS installations, and possibly deal with some hurdles concerning boot mode and the partition table.
Install Windows in BIOS mode -- You can boot the Windows installer in BIOS/CSM/legacy mode and install it that way. The result will be that both OSes will boot in BIOS mode, and you won't have to re-install your 32-bit Ubuntu. In the long term, though, you'll deal with the drawbacks of a 32-bit Ubuntu installation, slightly slower BIOS-mode booting, and perhaps other minor disadvantages with to this installation method. There's also a modest chance that the Windows installer will damage the partition table. (It does poorly with MBR configurations with more than four partitions.) Thus, backing up your personal data, just as in the preceding option, is highly recommended; and you may have to deal with unexpected problems.

Key to either of these options is learning how to control your boot mode. Unfortunately, details vary from one computer to another. Completely disabling the CSM is usually a reliable way to force an EFI-mode boot, but the option to do this in the firmware setup utility goes by various names, so you may end up poking around a bit to find it. If you go with a BIOS-mode Windows install, you'll need to find an option to boot the installer in BIOS mode. Typically, the computer's built-in boot manager has two options to boot external media. One option usually includes the string "UEFI" and boots in EFI mode, while the other option lacks this string and boots in BIOS mode.

Complicating this control is the fact that boot media may include BIOS-mode boot loaders, EFI-mode boot loaders, or both. If the medium lacks a given boot loader, you won't be able to boot it in that mode. Tools to convert .iso files to bootable USB flash drives can omit one or the other boot loader, even if the original .iso file has both. Thus, you may need to adjust options in whatever tool you used to create the .iso file or switch tools entirely.

For more on the CSM, see my page on the subject.


Ubuntu 20: Gedit missing from Activities Menu

Work Around option
Copy-paste content of original gedit.desktop file to a new .desktop file
Open the terminal and do
cd ~/.local/share/applications
sudo cp /usr/share/applications/org.gnome.gedit.desktop textEditor.desktop
:))


Installed mouse cursor theme but it only shows in some applications

First of all, change the permission of extracted directory (including sub-directories and files) to 755:

sudo chmod -R 755 cursors/

Then change the theme presented in /usr/share/icons/default/index.theme to your Cursor theme

Then Select it in gnome-tweak-tool

I've tried every instructions and it didn't work (default Arrow cursor remained DMZ-White), until i changed the permission.

Hope it helps.


Problem with apt-get upgrade and dependencies

Let's take a look at the key part of the error message:

Los siguientes paquetes tienen dependencias incumplidas:
  libgail-3-0 : Depende: libgtk-3-0 (=3.22.30-1ubuntu4) pero 3.22.30-1ubuntu1 está instalado
  libgtk-3-bin : Depende: libgtk-3-0 (>= 3.22.30-1ubuntu4) pero 3.22.30-1ubuntu1 está instalado

It says that you are trying to upgrade newer packages with older versions. Read it again, playing close attention to the difference between the version numbers.

Let's use a handy apt tool to see which repository these packages came from:

$ apt cache madison libgtk-3-bin
libgtk-3-bin | 3.22.30-1ubuntu1 | http://us.archive.ubuntu.com/ubuntu bionic/main amd64 Packages
libgtk-3-bin | 3.22.30-1ubuntu4 | http://us.archive.ubuntu.com/ubuntu bionic-updates/main amd64 Packages

Oh look, BOTH packages are listed. One is in bionic, the other in bionic-updates.

So the system is complaining that it NEEDS the version from bionic-updates, but cannot install it.

Time to look at your sources in your Software & Updates control panel (or in /etc/apt/sources.list). Ensure that the repo for bionic-updates is present and enabled.


sleep() function in C doesn't work on Ubuntu 20.04 (WSL). Is there any way to make the sleep() work?

sleep() is a system call. In WSL 1 the instructions are translated and further handled by Windows NT kernel since WSL 1 doesn't consist of a real Linux kernel. On the other hand, WSL 2 consists of a real Linux kernel built by Microsoft based on the Linux kernel's source code and thus handle system calls.
For your reference this is an overview of WSL 1 architecture:

And this is an overview of WSL 2 architecture:

Image credits: What is Windows Subsystem for Linux (WSL and WSL2)? — Linux in Windows - FOSSBYTES
So, there's no guarantee that all system calls specific to Linux kernel are translated and will be understood by Windows NT kernel.
To make sleep() work, you need to use real Linux kernel, i.e., WSL 2. To see which WSL version you're currently using, open command prompt or Powershell and run
wsl -l -v

This would list all distributions you're currently using with the WSL version and state. To switch WSL versions run
wsl --set-version distributionName WSLversion # eg:  wsl --set-version ubuntu-20.04 2

You might need to install the kernel first. You can refer to Update to WSL 2 - Microsoft Docs.

On a lighter note, sleep() takes time in milliseconds as an argument and 1 ms is very less to be noticed. I suggest trying with at least 15000 ms, i.e., 15 seconds.

Relevant topics:

WSL System Calls - Microsoft Docs

Windows Subsystem for Linux Overview - Microsoft Docs

What's New in WSL 2? - Microsoft Docs

Comparing WSL 1 and WSL 2 - Microsoft Docs

What is Windows Subsystem for Linux (WSL and WSL2)? — Linux in Windows - FOSSBYTES


Extending Ubuntu partiton on a windows dual boot

This is a very common task with dual boot systems, and your setup looks fairly standard so it should be fine, its just that some partitions may have to move as well as resize to create the space, which is all easily doable. There are a lot of existing guides such as the one posted in the comment above, and the simple guide I followed is listed in my tips below.  Its not hard to do, nevertheless feels "scary" even for more experienced users - just have everything backed up and there is no problem!
Many guides are old and do not mention some extra complications present in some modern dual boot systems, such as Bitlocker and Secure Boot.
Preparation Tips

Create a bootable Live USB: with gparted on it (I like to use DRBL Live USB, which has both Clonezilla and gparted on it).
BACKUP Recommended: use a Clonezilla live USB to back up the entire drive and all its partitions.  Or at minimum, back up your important files and documents you cant afford to loose!
Bitlocker: If you have Bitlocker encryption on the Windows partition, you must first log into Windows and disable it, then wait for the drive to decrypt before proceeding with resize.  This can take a while, be patient.  By the looks of it if you can see the used/free space of the Windows partition in Linux then you likely dont have Bitlocker.
Secure Boot: If you have Secure Boot enabled in your BIOS, you will likely need to disable that as well in order to boot from a Live USB drive.  You can always re-enable later if you really want it.

Perform the resize

When ready, follow the steps here to resize, beginning with step 2 if you already created the DRBL Live USB like I mentioned above. To boot from your USB drive, you will need to search for instructions specific to your PC or use the UEFI menu.

It might take a very long time to resize. On a very fast nvme drive it took about 12 minutes to resize a 250GB partition, but slower PCs or larger drives could take hours.

If your PC fails to boot after resize DONT PANIC. This often happens with older systems as the OS partition moved and bootloader cant find it.  Modern GRUB versions can usually autodetect changes.  Check here for solutions.


Software to automatically remove background from images?

The imagemagick package includes a convert command.

Example commands:

convert image1.jpg -fuzz 20%% -transparent White image2.png
convert image1.png -threshold 10%% image2.png

Both are simple versions of removing a background and might make all other none-background white in the image transparent (the fuzzy/threshold options can adjust that).

But Imagemagick has examples on removing backgrounds using masks.

What works best depends on the original. JPG tend to be fuzzy (what looks like the same color often are slightly different colors) so they will have mixed results.


Startup Applications missing from System Settings screen. Where can I find it?

Startup Applications can be found in the Panel in the upper right of the screen below the screen icon:

HTH. Have a nice day. :)

Just moved a bit, but it is there.


How to manage multiple imap accounts with mutt

Even though there are some useful guides on this site and this one, I thought I would just show you my currently working solution. You might note that it is similar to the aforementioned guides, but with additions and differences: I have found it is possible not to use account-hooks or folder-hooks in some cases. See the Mutt wiki for an alternative take on setting this up.

I will post the elements of the setup and then post my entire .muttrc so you can see how it all fits together.

It is easiest to enter the settings of both of your accounts in separate files and save them in the ~/.mutt folder. As an example, your two accounts could be called account.gmail1 and account.gmail2. So create two text files with those names and follow this template below for the contents; they should be both identical apart from the user@ part; just replace all occurrences of that with your real email (e.g. mik123@) in both files.

set imap_user = "user@gmail.com"
set imap_pass = ""
set from = "user@gmail.com"
set realname = "user"
set hostname = gmail.com
set folder = "imaps://user@imap.gmail.com:993"
set spoolfile = "imaps://user@imap.gmail.com/INBOX"
set postponed = "imaps://user@imap.gmail.com/[Gmail]/Drafts"
set record = "imaps://user@imap.gmail.com/[Gmail]/Sent Mail"
set smtp_url = "smtp://user@smtp.gmail.com:587"
set smtp_pass = ""

Note that I have left the password blank (""), which means you will be prompted for it, and that is what I prefer, but you can integrate your own solution if you don't want to have to keep entering the password.
If you want a default account loaded at startup, you can use in your .muttrc a similar line to this, just specify your own config file.

source "~/.mutt/account.gmail1"
To actually switch between the accounts, place a shortcut in your .muttrc referring to the actual location and name of your account configs:

macro index <f4> '<sync-mailbox><enter-command>source ~/.mutt/account.gmail1<enter><change-folder>!<enter>'
macro index <f5> '<sync-mailbox><enter-command>source ~/.mutt/account.gmail2<enter><change-folder>!<enter>'
You will be able to switch between folders within both accounts with pager commands such as

macro index,pager ga "<change-folder>=[Gmail]/All Mail<enter>" "Go to all mail"

that are defined in your .muttrc; these will still work for each account (see my attached .muttrc).

I tested these particular settings with the additional general ones in my .muttrc, so you can use that file and/or collate it with your own, it is up to you.

Now just load mutt in terminal and you should be able to load up one account and then switch to the other one using your shortcut. My .muttrc is pasted here if you need a working example of a configuration.

See the good article on this site on Mutt and the Mutt wiki for further ways of setting up mutt such as using folder-hooks to associate setings with various mailboxes, which is also explained here.


Disk Drive / not ready yet or not available

This code works fine on my machine (try it just once and the problem should be fixed):

mount -o remount, rw /

My Ubuntu is:
Ubuntu 12.04:  3.2.0-49-generic #75-Ubuntu x86_64 GNU/Linux


How do I turn "sudo apt-get" text into clickable download links in Firefox?

The solution comprises two steps:

connect firefox and apt-get
modify apt-get install textual content of web pages into hyperlinks pointing to apt://...

Regarding the first step, there's apturl to handle hyperlinks that implement the apt:// "protocol".

Regarding the second step, you could use the greasemonkey add-on together with a greasemonkey script that modifies the page content as desired. I didn't test it myself, but there are different examples to do this only, for example the "Apt-Linker for Greasemonkey" script.


The system is running in low graphics mode?

I had the same problem, and if I remember well, I reinstalled ubuntu...

Did you tried to do as it says here ?


Are you sure Ubuntu was installed ? If so, then you can recover your grub .
Follow the procedure as explained on this post.


Dual boot : Ubuntu detects Windows Boot Manager instead of Windows 7

Yup, it's perfectly safe. I dualboot Windows 7 with Ubuntu 14.04 LTS as well.
You get Windows Boot Manager because the boot partition of Windows was installed in another partition. (sda2 as shown in the picture below)

Once you select the boot manager, it will ask you to select Windows 7 and then boot it up.


Music player / database for read-only music collection

Try foobar2000 with the m-TAGS plugin. It is a Windows program, but runs reasonably well with Wine.


please, use this command in thumbnailer

Exec=/usr/bin/convert %i -resize %sx%s png:%o


Because Google Chrome uses deb packages in the distribution, the full Chrome package will be downloaded for each release. In using deb packages and the dpkg framework, it's not possible to use the patching system that it uses on Windows.


I am also using Ubuntu 16.10, and the default version of mysql-server in my computer is 5.7 and it's working fine.

Try following commands:

    sudo apt-get install -f
    sudo apt-get purge mysql-server-5.6
    sudo apt-get update && sudo apt-get install mysql-server-5.7

If you still get broken packages error, try sudo dpkg --configure -a to fix it. This might be also helpful for you to fix broken packages.

(PS: This may not work, I put my answer cause I don't have enough reputations to comment, Hope it can help you!)


Alternative to sudo add-apt-repository ppa:upubuntu-com/web

Follow the instructions on adding PPAs here: What are PPAs and how do I use them?
(alternatively, use the method below)

Yes. The PPA page on Launchpad has the information needed in "Technical details about this PPA":

Select the version from the drop down and it will show you the exact lines to copy. For example, for 12.04 (precise), you can add the following two lines to your sources.list file, or a new .list file in /etc/apt/sources.list.d:
deb http://ppa.launchpad.net/upubuntu-com/web/ubuntu precise main
deb-src http://ppa.launchpad.net/upubuntu-com/web/ubuntu precise main

You then need to run the following, using the key fingerprint:
gpg --keyserver subkeys.pgp.net --recv DED04C8CBB517AE45B073F12A5D712AEE06E6293
gpg --export --armor E06E6293 | sudo apt-key add -

Or use a web interface like http://keyserver.ubuntu.com/ to get the key manually, and then add it using sudo apt-key add path/to/file.
Then update your sources to use the new PPA:
sudo apt-get update


Does the Picasa 3.9 wine/winetricks/ie6 fix leave any vulnerabilities?

Adding Wine of Winetricks does not make your system vulnerable.

However, applications which run in Wine are vulnerable as if they were on Windows, in the sense that if you for example run IE6, it is suceptable to vulnerabilities just as if it were running on Windows. To make it more secure, you can use a Firewall, and only use it to login the one time that is needed. Beyond this point, you should have no worries about vulnerabilities.


How can I get access to python 3.4 after installing Anaconda?

You have to add anaconda path to your .bashrc file like this:

# added by Anaconda2 4.2.0 installer
export PATH="/home/george/anaconda2/bin:$PATH"

Why your installer didn't add it is another issue, but source your .bashrc file just to be sure, or better still look in there if not there then add the line above and source it to make it take effect.


VNC Viewer unable to connect: Encryption Issue

Oh, okay! Good news! I found out the issue. I did the command on the top of my question, but this time without sudo. This managed to do the trick, and it works great now! So follow the command above, but do NOT use sudo.

gsettings set org.gnome.Vino require-encryption false

run the command like this, without the sudo.


if you've installed amdgpu on Ubuntu 18.04.4 then the radeon driver will have been disabled. You need the radeon driver for older cards - I have a Radeon HD5000 and a Radeon R9 290X. I was able to get the 290X running with amdgpu but the HD5000 stopped working.
Re-enabling the radeon driver and forcing the HD5000 to use it made both displays work again!
Here's what you need to do:

Delete the blacklist file for radeon (Store a copy of this first)
sudo cp /etc/modprobe.d/blacklist-radeon.conf ~
sudo rm /etc/modprobe.d/blacklist-radeon.conf

Create an Xorg config file
sudo vim /etc/X11/xorg.conf

This should contain details of each of your video cards and which drivers you would like to use for them.
Section "Device"
    Identifier             "Screen0"
    Driver                 "amdgpu"
    VendorName             "Advanced Micro Devices, Inc. [AMD/ATI]"
    BusID                  "PCI:X:0:0"
EndSection

Section "Device"
    Identifier             "Screen1"
    Driver                 "radeon"
    VendorName             "Advanced Micro Devices, Inc. [AMD/ATI]"
    BusID                  "PCI:X:0:0"
EndSection

You can get the value for BusID (PCI:X:0:0) from the following command:
lspci | grep VGA

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Hawaii XT / Grenada XT [Radeon R9 290X/390X]
05:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Cedar [Radeon HD 5000/6000/7350/8350 Series]

The first card is on bus 1 and the value for xorg would be PCI:1:0:0. The second card is on bus 5 and the value in the xorg file would be PCI:5:0:0.
Hope this helps someone.


I'ld be more inclined to set up a docker container, but the deadsnakes ppa does carry various python builds you could install to get exactly the version you need.

For bionic, they do have a few builds.


Make sure the information of the packages is downloaded correctly. On commandline this can be done with

sudo apt-get update

In the GUI package-managers, I believe should be an option like update packages or something like that, which does the same.


Add a custom command to your Nomachine NXClient, which says gnome-session --session=ubuntu-2d. That will launch Unity 2D which uses Metacity instead of Compiz. NX is not capable of using Compiz (Unity) or Mutter (Gnome Shell). Unity 2D with Metacity works nicely though.


How can I auto align desktop icons on right side?

Sometimes gconf-editor will reveal additional options.  In this case, there's nothing relevant in the apps/nautilus section.

This issue was queried on launchpad a couple of years ago :
https://answers.launchpad.net/ubuntu/+question/48705, but there was no bug filed subsequently.

Your only option is to manually align your icons.


Machine becomes totally unresponsive whilst modifying files via samba

I've experienced a lot of issues running anything on 11.04. The latest version introduces a lot of overhead. I've found that running 10.04 LTS is much more stable. I'm currently running a Samba file server on Ubuntu Server 10.04 and it runs like a dream.


Update Ubuntu 14.04 LTS to 14.04.2 LTS without any command

14.04.2 is only a version for the image release. The version of Ubuntu itself is still 14.04. The appended numbers on LTS versions are simply later image milestone releases, to differentiate them from the original installer images. If you've installed all the updates, then you have the same packages as are on the 14.04.2 image already. If you need the HWE updates, you can install them, though they are not necessarily required, depending on your hardware.


Is there software like Mac's 'Logic Pro'?

Linux MultiMedia Studio

sudo apt-get install lmms

is an easy to use but powerful piece of software for creating music.

It is included in Ubuntu Studio, which I highly recommend you to use as it bundles many other useful software for audio creation and editing. You can install Ubuntu Studio using the ISO image like you used to install ubuntu or you can install it from your existing intallation via the ubuntustudio-desktop package.

Ubuntu Studio comes bundled with lots of other software for media creation (video editing, graphics etc.) and also sets a new default theme. You may not want all of these things if you are primarily interested in audio software. For this reason, Ubuntu Studio is split up into a set of packages. For audio software you can install the ubuntustudio-audio package.


Fast LiveCD without xserver to look up mac adresses

Try System Rescue CD instead

http://www.sysresccd.org/


using ufw to block outgoing traffic to website

It will be:

sudo ufw deny out from any to _ipaddress_


How do I ensure that security updates are installed on Juju machines?

I think currently the options are:

Log into each node regularily and do package updates manually
Use Landscape (requires a subscription). There is a landscape client charm: http://jujucharms.com/charms/precise/landscape-client
For each node, manually do one of these alternatives using SSH login: https://help.ubuntu.com/community/AutomaticSecurityUpdates#Using_the_.22unattended-upgrades.22_package (easiest is probably just to run "sudo dpkg-reconfigure unattended-upgrades" and answer yes on all nodes)

This might be discussed here: https://blueprints.launchpad.net/ubuntu/+spec/security-r-juju-charms.

Whishlist:

Global environment/service/machine option to do automatic updates
Unattended updates subordinate charm to associate with nodes I want to automatically update. Seems it is made here: https://bugs.launchpad.net/charms/+bug/1160736 and it waiting to be included in Charm store.


The reason why the inetaddr is missing could be that you're not connected to the internet.

As was in my case, if your Linux is hosted in a VM, ensure you have enabled networking.


What does "apt-get install !!" do and how to make it work?

!! is a shortcut in bash that means last command executed.

Try this:

 echo hello
 !!

In this context, the !! will be expanded to another echo hello.

I imagine what happened was they tried to run a command and it failed and complained it wasn't installed.  So then they typed sudo apt-get install !! because the package name was coincidentally the same as the name of the command they tried to run.  The resulting command would attempt to install a package by the same name as the command they had just attempted to execute.


How can I make sure that pinning with apt-get is compatible with virtual packages?

I found the problem. I made a mistake with the pinning conditions.

Edit:

The version of the pinning did not match what could be found or was missing for the package depending on the virtual package.


You best bet would to use Play-ON-linux and Wine, then install the proprietary software needed.

For Play on Linux:

Ubuntu
Deb files:

PlayOnLinux_4.0.16.deb

For the Oneiric version

Type the following commands:

wget -q "http://deb.playonlinux.com/public.gpg" -O- | sudo apt-key add -
sudo wget http://deb.playonlinux.com/playonlinux_oneiric.list -O /etc/apt/sources.list.d/playonlinux.list
sudo apt-get update
sudo apt-get install playonlinux

For the Natty version

Type the following commands:

wget -q "http://deb.playonlinux.com/public.gpg" -O- | sudo apt-key add -
sudo wget http://deb.playonlinux.com/playonlinux_natty.list -O /etc/apt/sources.list.d/playonlinux.list
sudo apt-get update
sudo apt-get install playonlinux

Configuring Wine can occasionally be a challenge, but Wine installs quite easily and runs just fine on Ubuntu. To install Wine, use this command at the Terminal prompt:

sudo apt-get install wine


how to create an empty virtual machine without os in kvm?

First, create an empty image which will be used by the virtual machine to store data as:

qemu-img create vm_no_os 8G

Here, an 8GB disk is created of type raw with name vm_no_os.

Next, use this image as the hard-disk for the virtual machine and boot the virtual machine without any OS:

qemu-system-x86_64 -m 512 -hda vm_no_os -name vm -net nic

Here, you can replace qemu-system-x86_64 with qemu-system-i386 if you are using a 32-bit system.

-m 512 represents using 512 MB of RAM

-name vm represents a name given to the VM being created

-net nic creates a new Network Interface Card for the VM.

Refer manual page of qemu-system-x86_64 for more.


Most non tech savvy friendly Ubuntu version for a company to implement?

Ubuntu, clearly.

Gnome is built first of all to be easy to use. Whereas the KDE and, especially, XFCE people have other things on their agendas, such as Performance (xfce), Über-Modern technologies (kde) and so on.

Gnome is used by some of the major Linux implementers, such as the city of Largo or Swiss federal court - they certainly bought this argument.

  GNOME understands that usability is
  about creating software that is easy
  for everyone to use, not about piling
  on features. GNOME's community of
  professional and volunteer usability
  experts have created Free Software's
  first and only Human Interface
  Guidelines, and all core GNOME
  software is adopting these principles. (via http://live.gnome.org/SWOT)

I would not only recommend ubuntu, i'd strongly discourage you from using anything else. For any reason you like, but firstly Usability and Support.


All dpkg history is stored in

 /var/log/dpkg.log

If you specifically want apt-get history, you'll find it in .

  /var/log/apt/history.log


cpupower frequency-set asks for permission despite being added to /etc/sudoers

Your sudoers file entry does NOT give you root all the time, just when you invoke rootness by prefacing your command with sudo, e.g.
sudo cpupower ...


Ubuntu (and Linux in general) uses the X11 cursor format, which isn't supported by Windows. On Ubuntu, these files are located in /usr/share/icons/<name-of-cursor-theme>. The default is DMZ-White.

If you want to use the DMZ cursor theme on Windows, you can use this set converted to Windows cursor format: http://nighted.deviantart.com/art/DMZ-Cursors-58429447


ubuntu software center and update manager is not working

Reinstalling the corresponding package will solves your problem. Try the below command to reinstall the package mentioned in the error report.

sudo apt-get install --reinstall adobereader-enu:i386


Unable to uninstall fedora 24 and install Ubuntu

If you want make ubuntu 14.04 your primary OS for your laptop then do the following steps:

Download the ubuntu 14.04 iso file.
Download and install PowerISO on your System.
Install the iso in your Pendrive using powerISO  using terminal command wget or download physically and un-tar it. http://www.poweriso.com/poweriso-1.3.tar.gz
open powerISO and click on tool tab,the select Bootable usb.
Burn dialog box will open, choose the un-tar iso file and click on start button.
viola you are half way done.
Now restart your os and boot your lappy to read usb storage first.
Follow the instruction and your ubuntu will be installed..

Note: you can also install the powerISO package from here


Make Ubuntu 16.04 server ask for a password when logged in

AWS Linux system comes with by default key-based authentication,
if you prefer only password-based authentication, here are the steps

login using the key file,

ssh ubuntu@ip_address

change the password for the current user,

sudo passwd ubuntu

set the new password.

then change the ssd_config file to allow password-based authentication.

in file /etc/ssh/sshd_config

replace PasswordAuthentication to yes

save and exit.

now I strictly suggest you exit the system and try password-based method before you log out since if you log out messing up the sshd_config file, it is difficult to revert it.

try logging in with a password, and if it works.

set PubkeyAuthentication to no, to disable key based authentication.


Answer to question one is usually the Downloads folder under the users home directory.

Answer to question two needs more  information to be answered such as what do you mean by not working. Do you see your network but cant log in? can you see networks but  not yours? Does it say no wireless networks found? Any error messages?  All relevant information would be helpful.

This may sound foolish but make sure your wireless is turned on on your laptop. I know that some laptops have a physical  switch that can turn off the wifi so first step would be to verify that it is on if you have a computer with a physical switch.


E: Package 'python-software-properties' has no installation candidate

Install software-properties-common by running,

sudo apt-get install software-properties-common

software-properties-common package is an alternate one for python-software-properties.

for <= 12.04

sudo apt-get install python-software-properties

for >= 12.10

sudo apt-get install software-properties-common


Go to System settings -> Application appearance (or Workspace appearance).

In some items (Colors, Icons, etc) you have the option to:

Get new (you can search in a dialog box)
Import (search a downloaded file and install it)

In other items (Style):

If it's in the repositories: use synaptics (or similar)
If it isn't in ther repositories: see if there's a PPA and use it

There are other situations that involve compiling a theme, but that's a longer story.


I managed to get them automounting using AriOS Automount. I'll wait to see if anyone can explain why ubuntu isn't doing what I expect it to do naturally before accepting my own answer.


I would suggest starting with opening a terminal and checking the output of:

/usr/lib/nux/unity_support_test -p

If everything shows yes, your graphic card shouldn't have a problem with unity. If not, you'll have to switch something your graphic card supports, gnome is an alternative to unity.

Given that the problem isn't your graphic card and you havn't installed any new graphic drivers prior to this error I would suggest to reinstall unity.

sudo apt-get install ppa-purge
sudo ppa-purge ppa:unity-team/staging

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


How do I access my NAS from an application?

Connect to your NAS

Assuming that you can connect to your NAS via samba:

First create a folder where you will mount the NAS

sudo mkdir /media/windows

Now mount the NAS - in my case its on an IP address shown under a share called "tvshows" - connecting via a Guest account

sudo mount -t smbfs //192.168.1.64/tvshows /media/windows -o username=Guest,password=

Navigating using Sheetmaker

Start Sheetmaker - you will be able to browse to this folder:

Double clicking "windows" will show your NAS folders, for example:


How do I autohide the top panel in Unity?

You can't currently autohide the panel in Unity. It is also not a planned feature.

There are ways you could possibly make the panel autohide:

Post an idea on Ubuntu Brainstorm to add this option and hope a developer sees it and implements it or creates a for with this feature.
Report a bug on Launchpad stating that this option should be available and hope a developer sees it and implements it or creates a for with this feature. This will probably get marked as opinion or invalid or at best a wishlist bug.
Get the code and add this option then merge with trunk or create your own fork.

None of these are immediate or even likely.


Touchpad right click doesn't work on touchpad, only the buttons above it. Thinkpad 13

Install and open gnome-tweak and go to Keybord & Mouse >>> mouse click emulation and just click on Area and close the window.


Ubuntu Unity 16.10 'sudo: no tty present and no askpass program specified'

You should not use sudo in a script. You can use policykit instead of sudo in your script:

#!/bin/bash
pkexec env DISPLAY=:0 XAUTHORITY=/home/$USER/.Xauthority service cntlm stop & sed whatever is missing here
pkexec env DISPLAY=:0 XAUTHORITY=/home/$USER/.Xauthority service cntlm start

or, better yet . . . just do the sed command first and then restart the service so that you only need to enter a password twice

#!/bin/bash
pkexec env DISPLAY=:0 XAUTHORITY=/home/$USER/.Xauthority sed 'some sed stuff'
pkexec env DISPLAY=:0 XAUTHORITY=/home/$USER/.Xauthority service cntlm restart

Also, if you still have problems, I would suggest running the script from "startup applications" instead of from your .profile file. You can search for "startup applications in your dash"


Is there any lite Ubuntu version for an old PC?

You have Xubuntu

And Lubuntu

And Ubuntu MATE

I would go for mate, it looks very nice =D


How can I replace [0] with ascending numbers in a text file?

Perl to the rescue!

perl -pe 's/\[0\]/"[" . $i++ . "]"/e' < input

-p reads the input line by line and returns each after processing
s/PATTERN/REPLACEMENT/ replaces the pattern by the replacement. Square brackets in the pattern must be escaped to match literally, as they have a special meaning otherwise.
/e evaluates the replacement as code, so $i++ increments $i and . concatenates the result to the square brackets


How do I use gpg-agent as with ssh-agent+ssh-add?

I decided to have a look at this again and found out how it works. GPG uses the terminology "cache" for storing passwords. Two constraints can be imposed on the maximum storage time:

The time to keep a passphrase since the key was initially added.
The time to keep a passphrase since it was last accessed.

In addition, two variations exist for both constraints, one for GPG keys and one for SSH keys (if support was enabled).

The relevant manual page entries from gpg-agent(1):

   --default-cache-ttl n
          Set  the  time a cache entry is valid to n seconds.  The default
          is 600 seconds.

   --default-cache-ttl-ssh n
          Set the time a cache entry used for SSH keys is valid to n  sec‐
          onds.  The default is 1800 seconds.

   --max-cache-ttl n
          Set the maximum time a cache entry is valid to n seconds.  After
          this time a cache entry will be expired  even  if  it  has  been
          accessed recently.  The default is 2 hours (7200 seconds).

   --max-cache-ttl-ssh n
          Set the maximum time a cache entry used for SSH keys is valid to
          n seconds.  After this time a cache entry will be  expired  even
          if  it has been accessed recently.  The default is 2 hours (7200
          seconds).

Passphrases are always cached (in memory, not on disk! Verified with a git repo of $HOME), so there is no explicit need for ssh-add. For example, signing dummy data triggers the cache already:

$ echo | gpg -s >/dev/null
(passphrase requested
$ echo | gpg -s >/dev/null
(signing proceeds without asking for passphrase)

To make permanent changes to the cache settings of gpg-agent, edit ~/.gnupg/gpg-agent.conf` and add something like:

default-cache-ttl  60     # Expire GPG keys when unused for 1 minute
max-cache-ttl     600     # Expire GPG keys after 10 minutes since addition

I have tried to enable SSH agent support by specifying enable-ssh-support, but this makes the gpg-agent ask you for another key to encrypt the key, and then stores your private key in ~/.gnupg/private-keys.d/. No go for me, I'll stick to a dual ssh-agent / gpg-agent approach then.

Some bonus tips:

SSH agent's equivalent of max-cache-ttl-ssh can be specified when adding the key, for example: ssh-add -t 600 ~/.ssh/id_rsa
To prevent storing the GPG passphrase in the agent, disable the agent. In newer GPG versions the option --no-use-agent is ignored, but you can prevent the agent from being used by clearing the related environment-variable. Some ways to do so:

echo | GPG_AGENT_INFO= gpg -s         # temporary
export GPG_AGENT_INFO=; echo | gpg -s # until the current shell is closed


Sony Vaio Fit with Ubuntu 12.04, sound missing

I had the same problem (headphones working fine, but no audio from internal speakers) with the same audio specs under Ubuntu 13.04, Linux kernel 3.8.

I updated the alsa drivers according to the instructions given in the Ubuntu help wiki page on Alsa for my kernel version.

After installation of the new drivers (package oem-audio-hda-daily-lts-raring-dkms) and reboot, the sound worked perfectly.


Stop/kill running script if $USER != "root"

I would have done this like this:

#!/bin/bash
if [ "$(id -u)" != "0" ]; then
   echo "This script must be run as root" 1>&2
   exit 1
fi

Mind that id=0 is what is used inside the kernel to identify the superuser (or root).

edit: it will be even better to redirect to STDERR.

Here is a one-liner :)

(( EUID )) && echo ‘You need to be root.’ && exit 1


Combining PDF files while retaining bookmarks

Yes, this is possible with sejda:

Download and install the latest sejda-console debfile
Use the following commandline to merge your documents:

sejda-console merge -b  one_entry_each_doc -f file1.pdf file2.pdf -o merge.pdf

where file1.pdf and file2.pdf are the paths to your PDF files and merge.pdf the path to save the resulting PDF to. You can include as many PDF documents as you want.

-b one_entry_each_doc will discard of all existing bookmarks and replace them by one entry for each document. If you want to preserve all bookmarks for all documents you will have to use the -b retain option.

I am afraid there is no way to both retain all bookmarks and add a new entry for each document, at the moment. Though there is a feature request regarding this very functionality.

For a full listing of all sejda merge options check out my answer over at superuser.com.


Can not install simultaneusly gstreamer1.0-plugins-ugly:i386 and gstreamer1.0-plugins-ugly

This is a known bug, which has been fixed in bionic.

I built libsidplay in a PPA:

https://launchpad.net/~gunnarhj/+archive/ubuntu/libsidplay

So if on xenial or artful you can solve it by opening a terminal window and running these commands:

sudo add-apt-repository ppa:gunnarhj/libsidplay
sudo apt update
sudo apt upgrade
sudo apt install gstreamer1.0-plugins-ugly:i386


Looks like you broke the access permissions inside your user home directory by running applications as super-user within the same home directory. You can reset the ownership and thus regain access with:

sudo chown -R "$USER:" "$HOME"

See Why should users never use normal sudo to start graphical applications? for an explanation why you shouldn't use sudo to start graphical applications and How do I start Nautilus as root? for alternatives (applies to other graphical applications too).


While installing Ubuntu 20.04 some package are being removed..will this cause any problems?

When installing Ubuntu unneeded packages like packages for extra languages that you haven't selected during the installation of Ubuntu are automatically removed towards the end of the installation process, so that Ubuntu will not take too much space on the hard disk. The reason why removing unnecessary packages occurs towards the end of the installation process is in order to give the Ubuntu installer a chance to calculate the package requirements after drivers, third-party codecs and updates have been installed if these options were selected, so that the Ubuntu installer can check if there are any packages that are no longer needed and can be safely removed.


Lubuntu 18.04 Steam not loading properly

try purging steam

sudo apt-get remove steam
sudo apt-get purge steam

then remove files

rm $HOME/.steam* (i think .steampid is the folder you want to delete here)

then reinstall steam.


Is there a PPA with the latest version of LibreOffice?

There is an official LibreOffice PPA here.

You need to add ppa:libreoffice/ppa in your software sources to add it to the software center, just follow the instructions for the GUI way.

More information:

Is the ppa of LibreOffice to be considered safe for the system?

To add ppa and upgrade libre office using command line:

sudo add-apt-repository ppa:libreoffice/ppa
sudo apt-get update
sudo apt-get upgrade


Ubuntu Server - Synchronize Dropbox with no logged user

The problem was the home directory was encrypted!
Just followed this article to disable encryption, reboot and it works.


In the specific case of files for a web server, it's ok to simply give ownership of that directory to the ubuntu user.

 sudo chown -R ubuntu:ubuntu /var/www

Then you can drop files there easily.

You might also find some useful information about the EC2 user setup on Ubuntu in this article I wrote a while back:

  Using sudo, ssh, rsync on the Official Ubuntu Images for EC2
  http://alestic.com/2009/04/ubuntu-ec2-sudo-ssh-rsync


Did Ubuntu move from installing an MTA by default to not installing an MTA by default?

Default MTA for Ubuntu is Postfix. You still to install it. Exim is still in the repo's. It sounds like you probably installed a package which pulled Exim in as a dependency.


Acer swift 3 high CPU temperature and fan not running

Configuration

Computing device=Acer TravelMateB113
cpu = i3-2377 (Sandy Bridge), TDP=17watt[1]
sys = Ubuntu 20.04 LTS

Situation:

permanently removed the rechargeable battery from computing device
upgraded dual install of Ubuntu 14+16 to Ubuntu 20
The system now randomly emergency shutsdown, sometimes even 5 secs after login to an account = 40 secs after boot (see [2])

Suspect: overheat
Diagnosis:
% grep -i -e therm /var/log/syslog*

No matches found except for Registered thermal governor ... and thermald: [WARN] ... Heat seemed to build up too fast up to emergency shutdown for any log facility to emit a warning or panic message.
Reading into the matter of system/intel-cpu heat reduction,
suggested topics:

Running Average Power Limit – RAPL
Power State (pstate)
thermal daemon

The cpu does an emergency shutdown once 100C° have been sensored.
Question: Why does heat build up in less than half a second from 50°C to 100°C ?
Suspect: intel turbo boost
Disable it:
% cat /sys/devices/system/cpu/intel_pstate/no_turbo

% echo "1" | sudo tee /sys/devices/system/cpu/intel_pstate/no_turbo

On login to an account the fan still started to vent at limits ([2]).
And the system still did emergency shutdown once an internet-browser was executed.
Used
% top

to identify the most cpu% consuming processes on login to an account.

tracker-miner-fs
snap-store
Both of these produce heavy io-load (disk read and also write, monitorable with i.e. iotop).
Disabled trackers as suggested on Ubuntu help www-pages.

Turned attention to thermald, sensor-polling cpu heat at 1 Hz (once per sec), probably too slow to be useful in this scenario. As suggested in docs for thermald: disable thermald, reboot, launch it without daemon and read the log output to std_out on terminal:
% systemctl disable thermald
% reboot
% ps -e | grep thermald  # make sure that no thermald is running

thermald --no-daemon --loglevel=info  # or: --loglevel=debug
% # use 'systemctl enable thermald' to reenable

The man page of thermald suggests to write a custom 'thermal-conf.xml'. There is a man page with some examples: man thermal-conf.xml
Yet, disabling thermald was sufficient to have the fan start venting early (built for TDP=17watt it is but a tiny fan, and now starts venting at about 45°C) to countermeasure uprising processing pressure heat. A ps auxc | grep -i therm now results in acpi_thermal_pm.
Summary: disable { intel turbo boost, tracker-miner-fs, snap-store, thermald }
trouble solving time: 20h
Thanks to gnu/linux/gnome/debian/ubuntu + trouble solving volunteers
refs
[1] in plain terms: a rather weak design on cpu-heat; see Intel Inc defs for reference.
[2] askubuntu.com/questions/1260698/high-cpu-temp-on-boot-fan-noise-on-ubuntu-thinkpad-t490/1260716#1260716
"Ubuntu boots with the CPU frequency scaling governor set to performance..."


Why system partition gets overfull quickly?

You can solve your issue using Recovery Mode

Only thing you have to do is to remove some junked files/folders from /dev/sda1 i,e where you have installed Ubuntu

Follow these simple steps:

Reboot your system and chose Recovery Mode (Safe Mode) 2nd option in Grub Menu.
Select grub option from the list (chose yes for the question)
Then go to root in order to login as root
Then execute these commands in series in order to free some spaces..

# apt-get autoclean
# apt-get autoremove
# apt-get clean

apt-get clean will remove packages that left after installing any package. So don't worry for that..
Then go to your Your Home directory and remove following directories ( I'm assuming that your Ubuntu's User name is 'maria`):

# cd /home/maria
# rm -r .config .local .cache .fontconfig

Above command will remove only your Users settings and Web history that you surfed using any web browser. So don't worry for that.. Your system will become new.
Then reboot your system:

# reboot

Hope after rebooting your problem would be solved. Reply for further assistance..


Here is the answer:

sudo dpkg --add-architecture i386
sudo apt-get update
sudo apt-get install wine

Worked


Inconsistent behaviour of applications and Launcher

You probably will want to directly call the launchers from the script, And create custom launchers for the java programs, Running a .desktop file in the terminal

How to make a launcher(.desktop file) for a binary file?

How can I add a bash script to the Unity launcher?

I'm making this Community Wiki so feel free to add and improve.


You can restart your computer and access recovery mode using the grub menu. Select "Drop to root shell prompt" and use nano or vim or whatever other text editor you have to undo the changes or simply use the copy and rename commands to reinstate you backup.

How to Access and Use Your Linux Distribution’s Boot Loader


Debian packages in private repository not visible in Muon

Muon (KDE Software) is like Gnome software, by default it shows only graphical tools. Filtering out some Debian package categories mainly used by advanced users.

Muon → View → Show technical packages


Stop Ubuntu 19.10 from asking for password from screen lock

Privacy" and turn off "Screen Lock" to disable the screen lock from being activated when your screen is blanked.

This will not prevent your lock screen from being activated when your computer resumes from hibernation or suspend.

To also disable the lock screen when resuming from suspend, set org.gnome.desktop.screensaver ubuntu-lock-on-suspend to false, as in

gsettings set org.gnome.desktop.screensaver ubuntu-lock-on-suspend false


How do I add Window Manager From Scratch (WMFS) to the Window Manager selection in the login screen?

From the ubuntu wiki:

  Ubuntu 12.04 uses LightDM by default.

  Create a new file /usr/share/xsessions/custom.desktop with:

[Desktop Entry]
Name=Xsession
Exec=/etc/X11/Xsession

  You should now have a new session option during login, Xsession will load the user's ~/.xsession file

The above allows you to create and use a .xsession file in your home directory. So now you should create said .xsession file and put the following in it:

exec wmfs

Then from the login screen you should see a new entry, log in with that and (hopefully) you should see your new, highly minimal window manager. Enjoy!


how to check what incorrect password as attempted

No, and that would be a HUGE security issue. Last time I checked anyone with a login or physical access to the machine can access this log.

I'm an untalented hacker and I want to elevate my rights on the machine: I would simply search the log for similar unsuccessful login attempt. Then I would be able to greatly improve the speed of a brute force attack.

What is it exactly you want to achieve? Some guru might be able to find a witty workaround for you.


/user/* is not a valid directory within a normal Linux system. It is /usr/. So ...

sudo cp -r apache-maven /usr/local/

can be valid. Though I probably would put maven into /opt/ myself.


How can I install a package in Gnu Octave?

run Octave as SU:

sudo octave

and then try the same as You did.


I was able to make it work through the command line based on this Ask Ubuntu answer and this Ubuntu Forums thread.

First unplug the bluetooth dongle and delete configuration files:

sudo \rm -rf /var/lib/bluetooth/*

Then replug the bluetooth dongle and run bluetoothctl. In the bluetoothctl prompt, type the following commands:

power on
agent on
default-agent
scan on

Turn on the bluetooth keyboard in discovery mode. Soon bluetoothctl will print the keyboard device ID in the format FF:EE:DD:CC:BB:AA. Then proceed with pairing:

pair FF:EE:DD:CC:BB:AA

It will request a PIN code, type that code in the keyboard and hit enter. You will get a success message. Then finalize the configuration:

trust FF:EE:DD:CC:BB:AA
connect FF:EE:DD:CC:BB:AA

The keyboard should now work.


External monitor resolution is 1024x768 (cvt+xrandr distorts the output)

Using -r option with cvt worked! I don't know what it means but it was the only command line option so I gave it a shot. With this option, cvt produced different parameters and those parameters produced a very crisp (even more than Windows) image.


Login failed when trying to log onto Ubuntu 16.04 from Windows 7 using Windows RDP

Based on the screenshots provided, you are using the xrdp version 0.6.x
this error can occur when password provided is incorrect.

Just an idea

By default, the xrdp login screen provided in the screenshot will use en-us keyboard layout.  Can you ensure that the password provided is correct based on your keyboard layout ? Type your password on the user name text box and check that the keyboard layout is not the problem...

Hope this help
Till next time
See ya


Various services (Terminal, gnome-disks, TTY) won't launch until I log out / back in

The goal is to make the "Ubuntu" environment work for you, and to move away from Wayland, as it's not really ready for prime time. There are a number of things that can be checked/tried.

Try and uninstall the Chrome Remote Desktop and the beta Chrome browser. Reboot. Retest the terminal app.
In terminal, type sudo dpkg-reconfigure gdm3, select gdm3, then reboot. Reboot into the "Ubuntu" environment and see if things are working now.
Check your file system...

For 18.04 or newer...

boot to a Ubuntu Live DVD/USB
open a terminal window
type sudo fdisk -l
identify the /dev/XXXX device name for your "Linux Filesystem"
type sudo fsck -f /dev/XXXX # replacing XXXX with the number you found earlier
repeat the fsck command if there were errors
type reboot

HOLD on this until we talk... after steps 1 & 2 & 3...

You may have a problem with an older computer, with an older GPU. Try this...

boot to recovery mode
choose root access

type:

sudo mount -o remount,rw /      # to remount the disk r/w

sudo pico /etc/gdm3/custom.conf # edit this file

change:

#WaylandEnable=false

to:

WaylandEnable=false

Then reboot into "Ubuntu" mode.


how can I publish my software for Ubuntu like extras or partner repositories, but closed source

I found a tutorial went through step by step to create a ubuntu repository on your own server.

Some key points:

1.Set up web server

Install Apache2

sudo apt-get update
sudo apt-get install apache2
sudo apache2ctl -k restart

setup configure

cat /Install Apache2/000-default.conf

make sure DocumentRoot /var/www is right

2. Create a deb package

build an executable named test

mkdir -p test/usr/local/bin
cp test test/usr/local/bin
vi /test/DEBIAN/control

enter

Package: test
Version: 1.0
Section: custom
Priority: optional
Architecture: all
Essential: no
Installed-Size: 1024
Maintainer: me
Description: Print hello on the screen

run

dpkg-deb --build petbotTest

3. put deb into special directory tree for apt-get to know

    cd /var/www
    mkdir -p repo/ubuntu_14.04
    cp /your_path/test.deb /var/www/repo/ubuntu_14.04
    dpkg-scanpackages ubuntu_14.04 /dev/null | gzip -9c > ubuntu_14.04/Packages.gz

4. for download

In your client computer:

sudo sh -c 'echo "deb http://YOUR_SERVER_IP/repo ubuntu_14.04/" > /etc/apt/sources.list.d/test_repo.list'
sudo apt-get update && sudo apt-get install test

5. to remove

sudo dpkg -P test


Install Canon 2900 driver in Ubuntu 16.04

you need the CAPT driver from here CAPT Printer Driver for Linux | Canon and click to download and SAVE and you will get linux-capt-drv-v271-uken.tar.gz

open a terminal and copy the commands below line by line and PASTE into the terminal

cd Downloads
tar -zxvf  linux-capt-drv-v271-uken.tar.gz
cd  linux-capt-drv-v271-uken/64-bit_Driver/Debian
sudo dpkg -i cndrvcups-common_3.21-1_amd64.deb
sudo dpkg -i cndrvcups-capt_2.71-1_amd64.deb

then sudo service cups restart

then to register the printer sudo /usr/sbin/lpadmin -p LBP2900 -m CNCUPSLBP2900CAPTK.ppd -v ccp://localhost:59787 -E

then to register with ccpd daemon sudo /usr/sbin/ccpdadmin -p LBP2900 -o /dev/usb/lp0

then restart ccpd with sudo /etc/init.d/ccpd start

...... and it should print

You must use the final command each time you turn the computer on; unless you set up the command to start automatically ...........

and this all assumes you have only ONE usb printer so it gets called lp0


How to start a VM on boot, and shutdown on VM stop?

I would go with a combination of cron job and usage of vboxmanage via bash scripts.

I'd have a bash script which would start up the virtual machines and fire up a cron job for checking the status of the machines.

The script should look something like:

#!/bin/bash

vboxmanage startvm "Server App VM name"
vboxmanage startvm "Windows XP VM name"
crontab ~/check_vms_and_shutdown_job.txt

Let's say we save it as start_vms_and_cronjob.sh. Remember to chmod +x it, so it can be actually executed.

You might wonder about the check_vms_and_shutdown_job.txt file. It's a text file containing information about a job that should be run at certain intervals. In this example we placed it in the user's home folder and it should read:

*/5 * * * * ~/check_vms_and_shutdown.sh

This file should have a new line at the end of the line (press enter before saving ;) ) What this file does is that it describes a cron job which is run every 5 minutes and it executes a bash script.

Now what is this check_vms_and_shutdown.sh script you might ask? Well, here's the whole point. It should say:

#!/bin/bash

if vboxmanage list runningvms | grep "Windows XP VM name"
then
    echo "Windows XP still running."
else
    echo "Windows XP shut down. Shutting down the rest."
    vboxmanage controlvm "Server App VM name" savestate
    crontab -r
    shutdown -h now
fi

Now what it does, that it will check if there is the XP virtual machine running. If it's not, it will then order the server app virtual machine to save it's state. After that the cronjob will be removed and the system shut down. Remember to chmod +x and here we also placed the file in user's home folder.

For convenience and better usage on the purpose you might also want to run the virtualboxes headless and have their usage be done through remote display.

Now add the start_vms_and_cronjob.sh into your startup applications and you should be set.

So what we have here is:

When the system starts, the virtual machines are started by a shell script and a new cron job (running a shell script) is created from a cron job rule txt file.
In every 5 minutes the cron job runs the script which checks if the XP virtual machine is still running and if not it will save the other virtual machine, remove the cron job and shutdown the system.

Hope this helps you to configure just what you need.


Brightness control not available in ubuntu 14.04 acer veriton desktop

command is not perfectly written..
I was having same problem too.. and sufferd a lot
 this  used to give me same error to  -   xrandr --output LVDS1 --brightness 0.5
 bt after searching .. i found out lvds1 is not the proper way to write
   right way is LVDS-1
this name u can find by running xrandr without any parameters :
hense use  this

xrandr --output LVDS-1 --brightness 0.5


This would require a Latin script translation package. Unfortunately, one does not exist for Japanese, and would need to be created. An appropriate locale definition for such a language pack would be ja@latin if you wish to take on the task of creating one.


Install rEFInd.
rEFInd is a boot manager that will allow you to choose between Mac OS X, Linux, Windows, and other operating systems when you boot your computer.

Partition your Mac.

Boot and install Linux.
Source: http://www.howtogeek.com/187410/how-to-install-and-dual-boot-linux-on-a-mac/
and http://lifehacker.com/5934942/how-to-dual-boot-linux-on-your-mac-and-take-back-your-powerhouse-apple-hardware


Why won't Steam work on my Dell INSPIRON E1705?

I looked up your Dell Inspiron e1705 specs and it seems to me like the integrated graphics from Intel or the optional Nvidia graphics chip that comes with it are not powerful enough to run the game.
The minimum system requirements for Team Fortress 2 are:
Graphics: nVidia GeForce 8600/9600GT, ATI/AMD Radeon HD2600/3600 (Graphic Drivers: nVidia 310, AMD 12.11), OpenGL 2.1
Your guess was correct, it's a hardware problem.


Why isn't Chrome rendering images and fonts correctly?

First see whether it has the same effect when you execute this command in your Terminal:

  sudo google-chrome --enable-webgl --ignore-gpu-blacklist --user-data-dir --enable-font-antialiasing

or this:

  sudo google-chrome --disable-gpu --user-data-dir --enable-font-antialiasing

Chrome has many different bugs regarding font rendering.

I suggest you to install Chrome's open source sibling Chromium by executing the below commands in your Terminal:

  sudo add-apt-repository ppa:saiarcot895/chromium-beta
  sudo apt-get update
  sudo apt-get install chromium-browser


This happens because the window compositor and decorator (compiz) is not running. It's probably crashing.

The black areas are "transparent" areas requiring a window compositor running.

Just to get you working again, install the package gnome-panel from the terminal. After booting, without logging in, press Control+Alt+F1, login in the console and use this command:

sudo apt-get install gnome-panel

Once you've installed gnome-panel, reboot or go back to the login screen with Alt+F7 and choose the session Gnome Classic (no effects).

To get compiz working again, so you can run Unity and Cairo-dock properly, we have to determine what's going wrong. That would be probably one of these:

Compiz is not installed properly. Run sudo apt-get install --reinstall compiz from a terminal to make sure that compiz is installed.
Your user profile has some bad configuration for Compiz. Create a new user and try to login with that user on Cairo Dock or Unity. If that succeeds, you'll have to reset the Compiz configuration on your user to fix it.
Your graphic drivers are not installed properly or are having some trouble running compiz. Run compiz --replace | tee output_compiz.txt from the Gnome Classic session to see what's going on. Paste here the generated file output_compiz.txt Please add what graphics card, driver are you using.

Please notice that, at any moment, you can login into a console by pressing Ctrl+Alt+F1 and run this command to kill your session:

killall gnome-session

This comes in handy if you're having trouble with the window compositor/decorator and want to go back to the login screen. Press Alt+F7 or Alt+F8 to go back to the graphical session after doing this.


Very high power demand after upgrading to 18.04

Problem: prime-select intel is not powering off the nvidia card

Workaround: Fast Switch Prime-Ubuntu-18.04


How can I change the keyboard model in 11.10?

There is a XKBMODEL variable in /etc/default/keyboard. However I don't know why was it removed from settings and what are the possible options.


If you have a USB drive that doesn't have any important data, I would recommend booting from an Ubuntu live system and reinstalling GRUB to your drive from there.

Watch this video. to find out how to do that.

It's a bit old but it is still for GRUB 2 so it should still work.
I haven't tried it though, sorry.


Ubuntu 15.10 DVD iso when boots is unreadable on a new PC with gtx 745 card

If you are simply trying to boot the live cd for the sake of installing it, then you can add nomodeset to the boot parameters.  For live CD's you usually need to select an "Advanced" option, but at some point you should be able to hit e to edit the boot parameters.

You will get a screen that will have a bunch of text, and one of the lines will start with vmlinuz ...stuff.. quiet splash.  Use your arrow keys to go to the end of the line and add nomodeset to that line, and hit F10 to boot.  stuff should be the kernel version, and possibly some other flags.  This will boot it in "Simple Graphics Mode" which should work even without the NVIDIA drivers installed.  It will be very poor resolution, but you can at least function.

The only other alternative I have ever had success with was connecting the monitor to the motherboard output (rather than the GPU), and it usually doesn't even use the GPU.  Sometimes, though, you have to actually disconnect the GPU...which isn't a very practical solution.


How to use hashed passwords with netplan (for wpa2 enterprise) instead of plain text passwords?

You are affected by https://bugs.launchpad.net/ubuntu/+source/netplan.io/+bug/1819831 for which a fix is in progress.

Note that while the linked question speaks of storing credentials "securely", the hash that is stored in the config is plaintext-equivalent.  If someone has this hash, they have everything they need to access this network.  So hashing should be considered a mechanism only of hiding the actual text of the password, and not a mechanism for protecting your network connection.


Ubuntu 16.04 not booting - shuts down after GRUB

You should have a Live install of ubuntu already.

boot to it and reinstall grub or try to mount the installed ubuntu partition.

you could also install auto repair on the live install and try to fix the problem.


Setting keyboard shortcuts to additional workspaces

It seems that GNOME Control Center keyboard shortcut do not allow to set shortcuts for workspaces from 5 to 12. But you can specify them using terminal (not user-friendly, but will work):

gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-5 "['<Ctrl>5']"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-6 "['<Ctrl>6']"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-7 "['<Ctrl>7']"
gsettings set org.gnome.desktop.wm.keybindings switch-to-workspace-8 "['<Ctrl>8']"

Small note: on MATE DE, which looks very similar to macOS (if Pantheon layout is used) you can define 8 shortcuts from GUI in user-friendly way (up to 12).


How does Juju "co-exist" with Chef, taking the automation process "one step further"?

awesome questions!

the tl;dr

I'd like to break your question(s) down over a couple of comments... first off, here're
a couple of general approaches to integrating chef and juju:

charms hooks can use existing chef recipes that run solo-style on service
units (recommended)
juju service units register with an existing chef-server using a chef-node subordinate
service

These ideas haven't been implemented/tested yet for chef, but the puppet
equivalents exist.

the... um.. not-so-short answer

Here's a little more of a breakdown of two approaches to integrating chef and juju:

Juju as top-dog

Here juju runs the show.  The biggest value juju provides is event coordination
during distributed configuration management... hence the "service
orchestration" moniker.  Juju charms consist of hooks which are called by juju
at "the right time" when coordinating service management.  The implementation
of these hooks is pretty much open.  They're shell scripts, source code, puppet
manifests, or... chef recipes.

Juju breaks bits of any service config up into:

"installation".. the bits that're specific to installing a particular service
onto a node
"relation".. the bits of config that're needed to relate that service to some
other service

The key to using chef recipes as hook implementations is exactly this... you
have to make sure that the recipes you're using respect this separation of
concerns.  Otherwise, there's nothing that prevents using off-the-shelf
cookbooks.  You can leverage existing recipes you've spent time/money to develop.... You
just need to make sure you can call the relation-specific stuff separately from
the installation-specific stuff.

We need some examples of this, but I think it'll be popular b/c chef has a
great dsl, a great templating tool, and is much more pleasant to use than bash
when writing complex config.  For simple config, chef recipes are a little
overkill imo, so this method of integration is pretty much the best of both
worlds... and has serious legs going forward.

Chef as top-dog

The idea here is to integrate juju services into an existing chef-server
managed infrastructure.  To do this, you'd need to write a chef-node
subordinate charm.  This subordinate service would be attached to primary juju
services and would effectively register these services as nodes (in particular
roles) with the chef server.  Subs can be attached during juju service startup,
or anytime later throughout each service's lifecycle.

I'm thinking this'd be quite similar to the puppet-node sub.  All necessary
keys, roles, etc would be specified via config to the chef-node subordinate
charm.  I'd start there.  A more sophisticated approach would be for the
chef-node sub to interrogate both the primary service it's attached to and its
chef-server to dynamically determine roles, but that'd be quite a bit harder
than just specifying them in config for the sub.

Opinions

I'd definitely recommend method 1 above, if possible.  Having the coordination layer on top of the configuration tools will probably work well long-term.  Needless to say, real-world infrastructures might be some combo or variation of both approaches for a period of time...  especially during migration.    Planned coexistance using method 2 would probably only work if the components managed by both tools were somewhat orthogonal to each other.  Not sure exactly what that would look like.  Perhaps juju and chef manage separate relatively decoupled services?  I suspect it might work well to let juju manage primary services and have chef manage more infrastructure aspects.  Dunno.  That's a bit of a longer discussion though :)

Side note... you can also use juju to manage chef-server itself... even large
complex multi-tier chef-server installations.  I haven't looked at the
chef-server charm lately, but if it doesn't currently handle tiering and
separation of services, then it can certainly be made to.

I'd love to see more examples of both types of chef integration mentioned
above... it's been on my wish / todo list for a while, but has yet to bubble up
high enough in priority to get done...  please help if you're interested!

ok, that's a decent chunk of rambling :)... let's start there, then we can go into more detail in subsequent comment blocks.


Possible to add all subdirectories when adding a directory to $PATH

This script uses tree ...

sudo apt-get install tree

You can change the depth of directories by changeing -L 1
and you can choose whether or not to use ~/ ...

UPDATE 2:
.. modified the script to replace only a leading /home/user/ (not "any")
.. and added args..

UPDATE Added check:
.. Don't add directory to PATH when it's already in PATH
.. This check considers '~/' and '/home/user/' to be different.

Re your question 1... yes it is true; each specific directory must be spedified individually in the PATH..

Re your question 2... Here is a script which will do what you want..
I've tested it, but as it stands it will make the new PATH for the current session..
To make it permanent you can use export PATH (but I'm a bit sketchy on the details of export)

#
# name: path-add-dirs
# eg: $ path-add-dirs "$HOME/bin" "tilde" 1

# When directories are $HOME based, choose format.
# Add directories in tidle format: ~/...
#       ...or as fullly-qualified: /home/user/...

# mode values: "tilde", or  anything else for fully-qualified
mode="$2" # valid mode values: "tilde", or  anything else
maindir="$1"; dirs= ; echo
# Buld string of subdirectories to a depth/level of 1
while IFS= read -r dir ; do
  # Don't add directory if it is already in PATH
  if [[ "$mode" == "tilde" ]] ; then
    # replace only a *leading* :/home/user/
    homecheck=":$dir"
    dircheck="${homecheck/:$HOME\//:~/}"
    dircheck="${dircheck#:}"
  else
    dircheck="${dir}"
  fi;
  pathcheck=":$PATH:"
  if [[ "$pathcheck" != "${pathcheck/:$dircheck:/}" ]] ; then
    echo "ALREADY IN PATH: $dircheck"
  else
    dirs="$dirs:$dir"
    echo " added: $dircheck"
  fi
done < <(tree --noreport -L $3 -fi -d "$maindir")
# Choose one of these two options
if [[ "$mode" == "tilde" ]]
then PATH="$PATH${dirs//:$HOME\//:~/}" # change :$HOME to :~/
else PATH="$PATH$dirs" # this method has fully expanded $HOME
fi
echo
echo "$PATH"
echo


COMPUTER NAME CHANGE

First, run sudo hostnamectl | grep hostname and confirm that's the name of the PC you want to change.

Next, run sudo hostnamectl set-hostname whatever where whatever is the name you wish to use henceforth.

Confirm the change was effective with sudo hostnamectl | grep hostname  to see the change was effective.

When I check the man page for hostnamectl, I can't see if it require elevated priveleges, so you may be able to do it without the sudo.

USER NAME CHANGE

Set the "root" account password with sudo passwd root then log out with exit and log in using the "root" account and the password you just set.

Change the username and the home folder to the new name that you want with
 usermod -l <newname> -d /home/<newname> -m <oldname>

Return the root account to its usual unreachability with passwd -l root then logout with exit.

Login with your new username.


What is the import process in Thunderbird for backup.pst files

Mozillazine Article says:

  There are several open source utilities to convert .pst files to mbox
  files such as readpst , libpst and Outport . Thunderbird uses a
  separate mbox file for each folder to store all of the messages for
  that folder. None of those utilities seem to be under active
  development and they only support some of the versions of .pst files.
  You can use the ImportExporttools extension to import the mbox files.

readpst is in the repos, but lacking a .pst file I can't try it


If you simply want to crop every page of a pdf, then I suggest Briss. It can not only crop a pdf but also produce more pages from a single page.

It is a simple yet effective pdf cropper.

To install,

download the briss-0.9.tar.gz file,
Unzip it somewhere of your choice,
Create a script (I named it briss.sh) with the following content:

cd /path/to/briss/folder/briss
java -Xmx256m -Djava.library.path=. -jar briss-0.9.jar

Make it executable (right-click on nautilus, permissions).

Create a briss.desktop launcher in /home/username/.local/share/applications:

#!/usr/bin/env xdg-open

[Desktop Entry]
Version=1.0
Type=Application
Terminal=false
Exec=/path/to/briss/folder/briss.sh
Name=Briss
Icon=/path/to/briss/icon/briss.jpg

Change the Exec line and the Icon line accordingly (I created an icon myself).

Make the .desktop file executable.
Run it as any other application.


Does your system has enough hardware resources? You can use light weight desktop manager like LXDE instead of Gnome / Unity. If you still prefer using Gnome / Unity then, you can use it without any effects (you can choose these options from the login screen). That is, Unity 2D:

How do I install and switch to the Unity 2D desktop?
How do I install LXDE / Lubuntu?
How to revert to GNOME Classic Desktop?


How to keep Thunderbird and Pidgin running on background?

EDIT 3: Thanks to @Mik and @Karthik How to emulate pressing the Close button from a script? we now have the best solution so far!!

You will need to install a Thunderbird extension:

MinimizedToTray revived (MinTrayR) 1.1.2
    To make Thunderbird minimize on messenger indicator on close and minimize go to addon's "Preferences" and check "Instead of closing and when minimizing"

You also need to install "xdotool" to properly run the script below:

sudo apt-get install xdotool

To make Thunderbird start on system login and immediately minimize create the script below:

Create an "Empty Document" in your Documents directory, name it "thunderbird_start.sh".

Copy in it the following lines:
    #!bin/bash

    #wait for internet connection up to 15 seconds
    host=google.com
    CONNECTED=$(ping -w5 -c1 $host > /dev/null 2>&1 && echo "up" || echo "down")
    STOPWATCH=0
    while [ "$CONNECTED" = "down" ] && [ $STOPWATCH -lt 15 ]; do
        sleep 1;
        CONNECTED=$(ping -w5 -c1 $host > /dev/null 2>&1 && echo "up" || echo "down")
        let STOPWATCH++
    done

    #run Thunderbird
    thunderbird &

    #Search for Thunderbird window
    TB=$(xdotool search --class thunderbird)
    while [ -z "$TB" ]; do
        sleep 10 #Adjust this to your system needs
        TB=$(xdotool search --class thunderbird)
    done

    #dispose Thunderbird window
    xdotool search --class thunderbird windowunmap %@

*I'm not very experienced in shell scripting so if there is any better implementation please let me know!

Open "Startup Applications" and "Add" a new startup program.

In the name field, give a name of your choice

In the command field add the following line:

    bash /home/your-name/Documents/thunderbird_start.sh

*maybe you could also use "~/" to get your home directory, but I'm not sure if is gonna work, you can try it: sh ~/Documents/thunderbird_start.sh

EDIT: MinimizedToTray officially does not support Unity so It breaks the global menu bar after restoring thunderbird. A work around is to disable global menu extension, till a fix release, or use HUD (ubuntu 12.04) to access thunberbird's options.

EDIT 2: I can confirm Karthik's comment, "MinimizedToTray revived 1.1.2" no more breaks Unity's global menu bar! Great thanks to Nils Maier...

EDIT 4: I've changed a bit the script code. I've added some lines to check for Internet connection so that sleep 10 is not needed any more...
ATTENTION in the 5th step sh was replaced with bash

EDIT 5: There is still a sleep 10 command in the script. You should adjust the sleep time according to your system's speed. For example in my laptop I have an SSD, so Thunderbird opens fast, sleep 2 works perfect. In my desktop PC I had to add 10 seconds of sleep to make it work properly... I have already issued an other question to overcome this limitation!


How do I set the number of workspaces without CCSM?

If you still can not use CCSM you could also add an indicator. See the image:

Add ppa:geod/ppa-geod to your Software Sources, update and then search for indicator workspaces or do a sudo apt-get install indicator-workspaces

References:

What are PPAs and how do I use them?


Installing Ubuntu on another Hard Drive Disk (F:)

Keep in mind that Ubuntu will not list your drives as C: D: etc. but will refer to them as /dev/sda, /dev/sdb, etc.

  Please make a backup of your important data to be able to restore them if anything fails by accident

Boot the CD, and start the installation.  Once you get to the installation screen, choose Something else

Choose the second Drive

After you choose it, click on Create new partition table, and just follow the rest of the steps, as shown in the images.


Updated to Ubuntu 20.04 -now the Super key (win) is not working

For me, the super key works only on the FIRST keyboard layout under Settings/Input sources. So I just dragged 'en' to be the first one.


BIOS-Access Problems on Lenovo, Xubuntu installed over (a deleted) Windows 8

The Novo button on Lenovo's can usually give access to the BIOS settings and the button looks like

Shutdown the computer and use the button to start the computer and you should see a menu like

And from there you can get into the BIOS settings


How to hide a window from Super + W overview mode?

Simply minimize the window. Example from my 16.04  desktop:

Image 1: Terminal window not minimized - shows up in the window spread

Image 2: Terminal window minimized - doesn't show up in the window spread


You have to install the corresponding -dev package by:
sudo apt-get install libvulkan-dev

And also please note that VKD3D is packaged in Ubuntu, so you can install it with:
sudo apt-get install libvkd3d-dev vkd3d-demos

and then reboot, and check it by running gears-vkd3d demo.


Document Viewer (Evince) does not remember last page in 20.04

In my setup with Evince 3.36.7 on Ubuntu 20.04.1 LTS, the Evince viewer's behavior is exactly as follows.  If you happen to close the document at the last page, then the next time you open the same document it will open the same document at first page.  This is somewhat confusing if users don't know this behavior.  This means if the document has n pages, Evince will only remember last page if you close the document at page 2..n-1 and will return to the first page otherwise.  I suppose this makes at least some sense, since you can always go to the first and last page with home and end button on the keyboard.


How can I restore grub after switching from Windows 8 to 7 on a dual boot?

There are two ways to fix that,
1) After installing Win7, try re-installing grub from live ubuntu.
(or)
2) Use Easy BCD from Win7 to bring back grub entries.

Hope it helps :)


Are snapcraft.io apps 'main' repositories?

apt uses repositories (apt is used by many debian based unix flavors like ubuntu) - they install packages sometimes called debs (deb from debian)
ubuntu repositories have several types of repositories

Main - Canonical-supported free and open-source software.
Universe - Community-maintained free and open-source software.
Restricted - Proprietary drivers for devices.
Multiverse - Software restricted by copyright or legal issues.

snaps are another way than apt to install software for ubuntu
they don't use apt repositories
snaps are managed by snapcraft.io and the store can be found here : https://snapcraft.io/store
Canonical, the company that publishes ubuntu also manages the snapcraft.io store
but snaps can be installed on other unix flavors than ubuntu too

this answer explains why snaps were "invented" by canonical/ubuntu
Why is Ubuntu moving to Snap packages?


First of all, there is no difference between a for loop for directories and one for files. It's exactly the same thing. Remember that on *nix, everything is a file.

So, your loop would be something like this:

for institute in institute1 institute2 institute3
do
    for scenario in scenario1 scenario2 scenario3
    do
        paste "$institute"_*_"$scenario"* > "$institute"_"$scenario".out
    done
done

If you don't know the institute and scenario names, you could just run this for all files and extract them from the filenames (as long as your names don't contain whitespace):

for f in *; do echo "${f/_*} ${f##*_}"; done |
    sort -u | while read ins sce; do
        paste "$ins"_*_"$sce"* > "$ins"_"$sce".out
    done


You need to put a shebang to make your file callable like a script. Try using a bash interpreter like this:

sylvain@sylvain-ThinkPad-T430s:/tmp$ cat>PinkBunny
#!/bin/bash
echo "Hellow Guys!"
^C
sylvain@sylvain-ThinkPad-T430s:/tmp$ chmod +x PinkBunny
sylvain@sylvain-ThinkPad-T430s:/tmp$ ./PinkBunny
Hellow Guys!


How to change the color of Chromium (only chrome) downloads bar in a GTK3 theme?

Using DK Bose and user3154748 help, I found this solution:

cp /usr/share/applications/chromium-browser.desktop ~/.local/share/applications

perl -i -pe 's/(Exec=chromium-browser)/$1 --enable-features=WebUIDarkMode --force-dark-mode/g' ~/.local/share/applications/chromium-browser.desktop

For the above to be effective, open Google Chrome > Settings > Appearance > Themes. There, ensure that Classic is being used and not GTK.


About the 'who' command & it's Output on '14.04 TrustyTahr'

Try upgrading the package that contains the who command; even if you did use a strange version of the ISO to install from, an update should replace it:

Find out what package owns who:

which who    # find out where 'who' binary is
dpkg -S /path/to/who

Then:

apt-get update
apt-get install <package name from dpkg -S command>

If it still doesn't work, try a different shell with no environment (to get rid of any wonky environment variables, setups, bash-specific junk, etc.):

env -i /bin/dash
$ who

If it works in a bare shell, then the problem is likely a weird alias definition in a bashrc, or something similar.

Also, does who --all work?


Try like this:

[...] first press Ctrl+R then start typing the command or any part of the command that you are looking for. You'll see an auto-complete of a past command at your prompt. If you keep typing, more specific options will appear. You can also press Ctrl+R again as many times as you want to, this goes back in your history to the previous matching command each time
Once you see a command you like, you can either run it by pressing return, or start editing it by pressing arrows or other movement keys.

Source: Navigating Bash History with Ctrl+R.


Exactly what the above comments mentioned, you will need to share the file system with the data from machine 2 back to machine 1.

Enabling NFS is probably what you will want and a simple HowTo at https://help.ubuntu.com/community/SettingUpNFSHowTo is a good start to just get a basic setup for testing.

Next you will likely want to performance optimize and this following article is a decent beginnning: http://www.slashroot.in/how-do-linux-nfs-performance-tuning-and-optimization