Accidentally took execute privileges off my /home

As bodhi.zazen says, you should boot to recovery mode and change the permissions back. Recovery mode should still work fine--this change is unlikely to render it unusable--but if for any reason you cannot use recovery mode, you can use a live CD/DVD/USB.

Hold down shift while booting so the GRUB menu is shown. Select Advanced options for Ubuntu, then select the first entry whose name ends in (recovery mode). Then on the recovery menu, select the option labeled:

root              Drop to root shell prompt

This should give you a # root shell prompt. Remount your / filesystem readwrite by running:

mount -o remount,rw /

(Note that you don't need sudo for that--nor for the chmod commands below--because you are already in a root shell, provided to you by recovery mode.)

Assuming the only changes you made were to execute permissions, you can then simply run:

chmod a+x /home
chmod -R u+X /home/tom

+X sets execute permissions specifically when a file is already executable by some user or a directory (see man chmod for details; note that capital +X is different from +x, which always sets execute permissions). On directories, execute permissions confer the ability to go into the directory. Losing that ability appears to be what has effectively locked you out of your account.

Since you just took away executable permissions, there's no need to walk the directory hierarchy with a more complicated find command and identify each file by type to change their permissions. Running chmod recursively with +X will make all the directories "executable" (i.e., enterable) by their owner again, which is precisely what you need here. (There's nothing really wrong with a find-based method, such as the one presented in tfmertz's answer--either way will work fine by itself. And if you happened to do both, what's fine too.)

Then boot normally, either by running reboot or by running exit (which brings you back to the recovery menu) and selecting the resume option.

Those chmod commands won't necessarily put things back to exactly what they were before--for that, it would probably be necessary to see what command you ran (but you may be able to find that by running history after logging back in). However, this will likely be sufficient to enable you to log in and use your Ubuntu system normally again.

This situation, and the solution, is similar to the more common situation where the sole administrator of a system has lost their password. Thus, while you're changing permissions rather than a password and the solution is not exactly the same, you might find it useful to take a look at How do I reset a lost administrative password? Some of the answers there contain screenshots showing how to get a root shell from recovery mode. And if you are unable to access recovery mode, the instructions there (and in this other question) about accessing your system from a live CD/DVD/USB should help.


Try this to fix:

You need to use the ntfsfix command, which is part of NTFS-3g. NTFS-3g should be installed by default.  If for some reason its not, then just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command below:

sudo apt-get install ntfs-3g

Once done, run this command in terminal:

sudo ntfsfix /dev/sda1

You may have to convert the volume.  To do that you might want to take a look at this.


terminator problem with running custom command in layout

ok I just found out :) I just need to add ; bash after the custom command, should be worth mentioning that in the menu...


Unable to install a kernel even though it compiled successfully

If you want to use another installed kernel, you need to choose it in the GRUB boot menu:

During boot, hold down either ESC (for EFI systems) or Shift (for BIOS systems).

Select "Advanced options for Ubuntu"

Select the kernel you wish to use.


There is no solution. When using Teams in Linux, you depend on the Linux version of the Teams' application as provided by Microsoft.
The Linux version is essentially a wrapped version of the web app and may not have all features of their dedicated Teams' application on the Windows desktop.
However, with respect to essential functionality, you are more than 95% set with the Linux or Web version.


How do I turn Ubuntu 12.04 server into an open SOCKS5 proxy?

You can fix the first error easily:

Go into the dash, and search Passwords and Keys. Go into your keys and go to File>New and chose the SSH key. Don't give it a password. Then, set it to use RSA, any key size, and then when prompted to set it up to be used for logon, allow it to do so, and choose the following settings:

Hostname: localhost
Username: Your username

and give your password if prompted. Reboot and try again with the first command.


The guest account is supposed to be there by default. And press "ctrl+alt+f1" all at a time to switch to tty1 and login with your user name and password. After logging into the tty1 shell, run sudo chown -R your_username:your_username /home/your_username, after a successful run, reboot your machine and see if it works.


How to use Cubic to create a custom Ubuntu live CD image?

Cubic (Custom Ubuntu ISO Creator) is a GUI wizard to create a customized Ubuntu Live ISO image.
Cubic permits effortless navigation through the ISO customization steps and features an integrated virtual command line environment to customize the Linux file system. You can create new customization projects or modify existing projects. Important parameters are dynamically populated with intelligent defaults to simplify the customization process.
Installing Cubic
To install Cubic, add the PPA, and install using apt.
sudo apt-add-repository ppa:cubic-wizard/release
sudo apt install cubic

Using Cubic
Launch Cubic from the dock or application menu.
The Start Page
On the Start Page, select a new empty directory to keep all your project files.  You can have multiple customization projects, but you must pick a different directory for each project.

The Project Page
On the Project Page, select an original ISO image to customize. Information on the Project page will be automatically filled out for you.  You can accept the recommended defaults.  If you chose to change some of the values, the related parameters will automatically be updated as you type.

The Extract Page
The next page will display progress as the original ISO is analyzed, important files are copied, and the compressed Linux file system is extracted.

The Terminal Page
The Terminal Page automatically appears once the Linux file system has been extracted.  This is a container environment in which you can make customizations using the command line.  Since you are logged in as a root user, you do not need to use sudo when typing commands. (You can safely ignore the "couldn't connect to zsys" error messages, or if you do not need zsys, you can execute apt remove zsys to eliminate these messages).
Use command line tools to customize Ubuntu.

Note, on some Ubuntu based distributions, DNS lookups may not work, and you may not be able to use apt due to a "Name or service not known" error. This is because the link /etc/resolv.conf points to /run/systemd/resolve/stub-resolv.conf. But stub-resolv.conf does not exist.
To resolve this,  execute the following command in the Cubic Terminal...
ln -sr /run/systemd/resolve/resolv.conf /run/systemd/resolve/stub-resolv.conf

Or try this approach, proposed by Ark74.
mkdir /run/systemd/resolve/
echo "nameserver 127.0.1.1
search network" | tee /run/systemd/resolve/resolv.conf
ln -sr /run/systemd/resolve/resolv.conf /run/systemd/resolve/stub-resolv.conf

To verify DNS resolution works, execute...
cat /etc/resolv.conf
ping google.com

Here are a few examples of customizing Ubuntu using the command line...
You may use the nano text editor to edit files.  For example, to edit the sources repositories list, type
nano /etc/apt/sources.list

To exit nano, type Ctrl-X and you will be prompted to save the file.  To not save the file, type N.  To save the file, type Y, and press Enter to accept the default file name.

After editing the sources list, remember to update the list of available packages using:
apt update

You can use apt to update sources and install applications.  For example, you can install other Linux kernels.
apt install linux-headers-5.8.0-44-generic linux-image-5.8.0-44-generic

You may click the Back button to change some of your the project parameters you entered on the Project Page.  If you quit the application, you can always open your project and continue making customizations on the Terminal Page, where you left off.

The Copy Files Page
You can copy files or directories into the current directory by dragging them onto the terminal window, by using the copy button in the header bar, or by using the right-click context menu.
The right-click context menu also allows you to copy-and-paste text in the terminal, or you can use Ctrl-Shift-C and Ctrl-Shift-V shortcuts.
Here is an example to copy additional wallpapers into your customized environment.
cd /usr/share/backgrounds

Then simply drag the new wallpapers onto the Cubic window, and click the Copy button on the Copy Page that appears.
Note that the Cubic GUI currently does not support copying files over the network, but you can use the rcp or scp commands from within the terminal environment.

Tip: Be sure to list the new wallpapers in an XML file under /usr/share/gnome-background-properties, so they will be listed in the Change Background dialog when the user right-clicks on his/her desktop.

When you are done making your changes, click the Next button.  Remember, you can always come back to the terminal environment for this project to make additional customizations in the future.
The Prepare Page
On the Prepare Page, Cubic will automatically identify kernels available to boot the custom ISO, and Cubic will create manifest files based on the installed packages. You do not need to do anything on this page.

The Packages Page
The Packages Page automatically appears, listing of all packages installed in your customized Linux system.  The packages with a check mark next to them are flagged to be automatically removed by the "Ubiquity live CD installer".  If you do not want Ubiquity to remove a package after installing your customized Linux system, simply un-check that package.
If your installer supports both Typical and Minimal installs, you will see two columns with check boxes.  When you select a package to be removed for a Typical install, the package will automatically be removed for a Minimal install as well.
If your installer does not support Minimal installs, you will only see one column with check boxes for a Typical install.
Be careful when selecting packages for removal, because additional dependent packages may also be removed, and these will not be indicated in the list. Here is an example where gparted was selected to not be removed (i.e. un-checked). However, gparted-common is still flagged to be removed. When the installer encounters this, it will remove gparted-common and gparted will automatically be removed because it depends on gparted-common.
Therefore, it's a good idea to just accept the recommended defaults on this page, unless you know what you are doing.

The Options Page
On the next page, you will see three tabs in the header bar:

Kernel Tab
Preseed Tab
Boot Tab

The Options Page - Kernel Tab
The Kernel Tab lists all the kernels available to boot your new Live ISO, including kernels you have installed to your customized Linux system.  You can chose to use one of these as the boot kernel for your new Live ISO.  It's a good idea to accept the recommended default on this tab.
(Note: On this page you are not selecting the kernel that is used inside your customized Linux system, nor are you selecting the default kernel that will be installed onto a computer by your new Live ISO; instead, this is the kernel that is used to boostrap your new Live ISO).
The ISO Boot files (listed on the Boot Tab) will automatically be updated with your selected kernel files (vmlinuz and initrd). Cubic will also automatically correct file extension (initrd.lz, initrd.gz, etc.) even if the original ISO had the wrong file extension.

The Options Page - Preseed Tab
The Preseed Tab allows you to optionally create, edit, or delete Preseed files.

The Options Page - Boot Tab
The Boot Tab allows you to optionally update the boot parameters used while booting the customized Live ISO. These files are automatically updated to reflect the correct kernel files (vmlinuz and initrd). It's a good idea to accept the recommended defaults on this tab.
(Note: On this page you are not updating the Grub boot loader files that are used to boot your customized Linux system; instead, this is the Grub boot loader that is used to boostrap your new Live ISO).

The Compression Page
The Compression Page allows you to select the algorithm used to compress your customized Linux file system (lz4, lzo, gzip, zstd, lzma, or xz).
Algorithms listed towards the top left of the chart are faster, use less CPU resources, but produce larger files. Algorithms listed towards the bottom right of the chart are slower, use more CPU resources, but produce smaller files.
For most users, it is OK to proceed with the default algorithm, gzip.

The Generate Page
Click the Next button, and Cubic will automatically package your customizations into a new *.iso disk image.  The progress and results of each step are shown.  Note that the "Compress the customized Linux filesystem" step may take a long time, depending on the selected algorithm and your system hardware.  (You may want to open System Monitor to track your CPU utilization during this step).
At any time during this process, you can click the Back button to immediately go back to the Terminal Page, and make additional changes or customizations you may have overlooked. There is no practical size limit for the generated ISO.
After generating the new customized disk image, Cubic will also generate an MD5 checksum file that can be used to verify your customized *.iso file.

The Finish Page
Click the Finish button, and information about the customized disk image will be displayed.
If you want to delete all working project files (in order to save disk space) check the "Delete all project files..." checkbox. Otherwise, you will be able to continue customizing this project in the future.

Click the Close button to exit Cubic.
Finally, use your favorite disk burning program, such as Brasero, to burn a copy of the *.iso image to CD or DVD, or use a USB image writing tool, such as Startup Disk Creator or mkusb, to create a bootable USB.
Using the MD5 Checksum
If you are distributing your customized Linux, the corresponding MD5 checksum file can be used to verify that it has not been altered.  For example, ensure both files are in the same directory, and type the following…
md5sum --check ubuntu-20.04.0-2021.03.04-desktop-amd64.md5

ubuntu-20.04.0-2021.03.04-desktop-amd64.iso: OK

Making Changes
The Project Page for an Existing Project
Launch Cubic, and select an existing project directory on the Start Page.  Click the Next button, and you see your Cubic project information. Simply click the Customize button in the header bar to go directly to the Terminal page to continue customizing your project to make additional changes.

The Delete Project Page
You can also delete an existing project by clicking the Delete button in the header bar. All project working files will be deleted and you will not be able to customize or make additional changes to this project.  If you do not want the generated *.iso image and *.md5 files to be deleted uncheck the "Delete..." check box at the bottom of the page.


Close all CALC windows
open a new one
Go to bottom right slider and move it to 100% (or whatever value you need)
Close CALC
open it again; cells are now in correct size :)

you can also do it from Menu > View > Zoom


Installing grub boot on Uefi 64 bit HP LAPTOP

Congratulations on getting the boot to work.  Let me describe the boot process a little, so you can decide what if anything you want to do about the boot order in the grub menu, which is really another question (answered elsewhere here).
  Legacy boot uses simple firmware that knows how to start executing at the first block of a device (the Master Boot Block or MBR).  This is grub-pc after you install it -- a small binary blob, which needs more code to do much (the second bigger binary blob called core.img, but since both binary blobs are not even in a filesystem, the concept of a "name" is misleading.  On an MSDOS type partition, the second binary blob fits into the partition structure right after the MBR, but on a GPT partitioning, there is no room there, so you need another place, the small 1M partition with the grub-bios flag.  Again, what's in this grub-bios partition is just a binary blob, no filesystem, so not much for you to "read".
  Enter UEFI, with smarter firmware.  Now the firmware knows about FAT filesystems, and can actually be set up to select a file in that type of filesystem -- no more binary blobs to worry about, just files.  You can use any standard file-copy mechanism to move these files, no more special tools needed to write binary blobs into selected block locations on the disk.   Now the location of this FAT filesystem for booting is any partition with the boot flag.  (However, on the current crop of hugh disks, maybe it's still good to keep it near the beginning of the disks).  All the bootloaders you want (space allowing), can go into the filesystem, which uses the standard directory/subdirectory method to keep them separate.  The Ubuntu bootloaders go into the /EFI/ubuntu (kubuntu, ... whatever) directory.  There is really only the new grubx64.efi, but it comes in both a cryptographically signed and unsigned version. Canonical signs the grubx64.efi, which basically still cannot run because the firmware only comes with the ability to run Microsoft signed code (when secure boot is enabled).  So Canonical paid Microsoft to sign a tiny little program which can only run grubx64.efi -- that's the shimx64.efi.  Nothing in this UEFI description precludes the use of the old MBR boot mechanism -- and that's exactly what the live media uses, both of them.
  I'd suggest reading more about UEFI, and look up the grub menu reordering if you want to change the grub defaults. Good Luck.


Try with SUPER + P (Super is WINDOWS KEY)
If this doesn't works try with sudo apt-get install arandr and then open the screen layout editor you just installed with arandrcommand.
Once you opened it you could place the second screen above the first to do the mirroring:

Once you've dragged the second one over the first one (DVI-I-1 over DVI-I-0 in my case) you could save it with the check mark (✓)
Done, you've just mirrored your screen. Have fun watching footbal on TV with your friends!
Psst! Have you tried by simply dragging the football match window on the second screen?


Setting a randomly generated password to a variable?

You have to use a command substitution:

#Generate random password
PASSWORD=$(date +%s|sha256sum|base64|head -c 32)
echo $PASSWORD

then it should work.

Prefer the "$" sign, read more here: Using backticks or dollar in shell scripts


How to configure a fallback static IP address when there is no DHCP server present

You can solve this by creating two profiles (aka. connection).

A DHCP config with high priority that tries for some time
A static config with lower priority that connects if DHCP fails

In config files (e.g. /etc/NetworkManager/system-connections/*.nmconnection) :

The DHCP profile

[connection]
id=dhcp
uuid=<an UUID>
type=ethernet
interface-name=eth0
autoconnect-priority=1
autoconnect-retries=2

[ipv4]
dns-search=
method=auto
dhcp-timeout=10
may-fail=false

The static profile

[connection]
id=static
uuid=<an UUID>
type=ethernet
interface-name=eth0
autoconnect-priority=0
autoconnect-retries=-1

[ipv4]
address1=192.168.1.10/24,192.168.1.1
dns=192.168.1.1
dns-search=
method=manual

Note : by default, autoconnect=true when not specified, otherwise it wouldn't work.


Firefox 57 shows dark input boxes/dropdown menus with dark text on Gnome dark themes

I found the best solution was to add a string value in about:config for widget.content.gtk-theme-override to override the GTK theme. You can use a related theme with light text boxes (obviously this only works for consistency if said related theme exists). For example, using Arc-Dark set the override to Arc-Darker which has light widget elements.

Credit for the solution here: https://www.mkammerer.de/blog/gtk-dark-theme-and-firefox/

-- sss


How to mount Touch phone as external drive on MacOS

You should be able to mount it if it makes a device node in /dev. Just watch for disk0s9, where 9 will be the partition #, to appear in /dev after you plug the device in. Then run 'mkdir /mnt/disk -p && sudo mount /dev/disk0s9 /mnt/disk' to make a folder to mount the disk to, and to mount the disk!


Xubuntu 13.04 boots to command line instead of GUI. How to get back GUI?

So I managed to get GUI back without any command line typing. I did nothing, just hit Enter on Ubuntu option the next boot attempt. Just didn't let GRUB stopwatch to reach 0 and didn't use arrows in GRUB menu, just hit Enter. Very strange.

First of all, I remember when it happened. I turned on the computer and left my room to do other things. Before it I always manually selected in GRUB menu what system to load, either Xubuntu or Windows. I never let GRUB stopwatch to reach 0 and boot itself, I always hit Enter earlier. So when I came back to computer I saw the command line prompt instead of GUI.

I didn't know how to restart Xubuntu safely from the command line, so in this situation I just hit the restart button. The following boot I immediate used arrows in GRUB to go down the menu (up to Windows XP option) and then go up to select Ubuntu again. Just to stop GRUB stopwatch. Then hit Enter. But got command line again. I again reset the computer with the reset button.

This time I switched to Windows, surfed the Internet for answers, wrote this question. Found this 7 pages thread http://ubuntuforums.org/showthread.php?t=1570540. A user experienced the same problem in 2010. The main solution is on page six http://ubuntuforums.org/showthread.php?t=1570540&page=6&p=9935242#post9935242. So I did the same.

I tried to boot again but this time I didn't use arrows. I just immediately hit Enter on Ubuntu option in GRUB. And I got GUI. Xubuntu is installed but GRUB's option is Ubuntu, not Xubuntu.

Xubuntu also fixed some crash when I entered GUI:

execution path:
   usr/bin/Xorg
package:
   xserver-xorg-core 2:1, 13,3 - Oubuntu6
problem type:
   Crash
title
   Xorg crashed with SIGABRT in raise()

So my conclusion is: if you want Xubuntu, immediately hit Enter in GRUB menu. Don't let stopwatch to get 0 and don't use arrows. I you want Windows, choose a Windows option using arrows and hit Enter. Isn't it ridiculous?


How can I get the Similar Package list from the terminal?

maybe

apt-cache search <package_name> | grep <another_keyword>


Where can I find video pixel formats' definitions/characteristics?

You can find it on this Linux Media Subsystem Documentation site:

YUV Formats:

Y8I: This is a grey-scale image with a depth of 8 bits per pixel, but with pixels from 2 sources interleaved. Each pixel is stored in a 16-bit word. E.g. the R200 RealSense camera stores pixel from the left sensor in lower and from the right sensor in the higher 8 bits
Y12I: This is a grey-scale image with a depth of 12 bits per pixel, but with pixels from 2 sources interleaved and bit-packed. Each pixel is stored in a 24-bit word in the little-endian order. On a little-endian machine these pixels can be deinterlaced using

Depth format Z16: This is a 16-bit format, representing depth data. Each pixel is a distance to the respective point in the image coordinates. Distance unit can vary and has to be negotiated with the device separately. Each pixel is stored in a 16-bit word in the little endian byte order.


Wireless stops immediately after I log in Ubuntu 12.04 LTS on Lenovo IdeaPad Z710

Your wireless might be disabled, run the following commands in the terminal (ctrl+alt+t):

iwconfig this will output the name of your wireless card, it's
usually wlan0
Assuming the name was wlan0, run ifconfig wlan0 up, if the name is
not wlan0 the replace it for the correct one.

I hope this helps, good luck.


Use disown command:

gedit & disown

This way launched process is disconnected from the terminal it was launched in.


not able to reach 'us.archive.ubuntu.com' through terminal

The problem can be solved by configuring the proxy for apt.check answer this answer


Getting error "dependency is not satisfiable libpng12-0" while installing TeamViewer

libpng is a library implementing an interface for reading and writing
  PNG (Portable Network Graphics) format files.

  This package contains the runtime library files needed to run software
  using libpng.

If you search in Synaptic you can install it and then install teamviewer, not sure what version do you have tho!


That has nothing to do with the distro. It sounds like your board is a little funky when it comes to general Linux support.

http://www.amazon.com/review/R1LPS5LC21G3ZA/ref=cm_cr_pr_viewpnt#R1LPS5LC21G3ZA

  This board is not directly compatible with Linux, specifically the
  built-in Ethernet. In order for it to work you must enable IOMMU in
  BIOS, but disable IOMMU on the linux kernel command line with
  “iommu=soft”. Without this all will appear working, but you will have
  absolutely no connectivity. This bug / compatibility issue affects all
  revisions past 1.1 that have the new UEFI BIOS.

So IOMMUs are usually a nice to have for virtualized environments, it basically lets you assign pci devices to virtual hosts. Why you would need to explicitly enable it to gain access to your RAID controller is weird. iommu=soft is really bad news for performance.

https://www.kernel.org/doc/Documentation/x86/x86_64/boot-options.txt

   General iommu options:
     off                Don't initialize and use any kind of IOMMU.
     noforce            Don't force hardware IOMMU usage when it is not needed.
                        (default).
     force              Force the use of the hardware IOMMU even when it is
                        not actually needed (e.g. because < 3 GB memory).
     soft               Use software bounce buffering (SWIOTLB) (default for
                        Intel machines). This can be used to prevent the usage
                        of an available hardware IOMMU.

What that means is the kernel has to copy whatever it needs to read/write to an intermediate location before it can complete the DMA. So at least a 2x latency hit.

You might be better off without it honestly. Consider using a different board for more intense server applications.


Ubuntu 16.04 not running scripts in /etc/profile.d/

Those files should be sourced by the display manager.

LightDM: /usr/sbin/lightdm-session

GDM: /etc/gdm3/Xsession

(I don't know how other DMs work in this respect.)

Please note that the script names must end with .sh.


Yes you can update linux kernel without updating your linux distro.
To install the latest kernel you can always visit http://kernel.ubuntu.com and https://wiki.ubuntu.com/Kernel to see what's going on.
As of today the latest kernel is 3.17.
If you are using ubuntu 14.04, for example goto this link: Install/Upgrade to Linux Kernel 3.17 in Ubuntu 14.04

Similar tutorials are for other Ubuntu version and other linux kernel version are available, just google it or comment here i'll help you.


Are there any unwanted gnome libraries for a unity user?

As Unity is a shell for Gnome you still need about all of the Gnome stack. Removing metacity and gnome-panel should be safe, but that doesn't free up much space.


How do I get Synapse to search my Tomboy notes?

I am the person who developed zeitgeist-datasource-tomboy. Due to tomboy note format you can only search by the title of the Note and not by the contents.

This is a limitation because for that the whole content of the note has to be stored as an event. (Actually it can be, but doesn't make much sense to fill the database with content already present in Notes)

Try searching by Note Title, if it doesn't work then I can look further.

If you have not enabled this plugin, then please goto Tomboy preferences, and check Zeitgeist Dataprovider


UFW Allows 22 for IPv4 and IPv6 but SSH Disconnects When Enabling

Background, and bounds for the issue:

The issue only occurs when UFW, or iptables, with these ssh allow rules, is enabled and an ssh session is started. i.e. Any SSH session that was started with no iptables at all works fine, but may be subject to random drop outs once the rule set are put in place.
recall that ufw is merely a front end for iptables.
The issue is present even with kernel 4.18-rc8.

What is going on?

The sudo ufw allow in port 22 results in the following iptables rules segment:

Chain ufw-before-input (1 references)
    pkts      bytes target     prot opt in     out     source               destination
      16     1553 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
     386   300622 ACCEPT     all  --  *      *       0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
      15     1068 ufw-logging-deny  all  --  *      *       0.0.0.0/0            0.0.0.0/0            ctstate INVALID
      15     1068 DROP       all  --  *      *       0.0.0.0/0            0.0.0.0/0            ctstate INVALID

Upon sudo ufw disable followed by sudo ufw enable, and even though the ssh connection itself remains fine, the resulting iptables rule set seems to have forgotten the association with that particular connection and therefore classifies any incoming packets as invalid. Somehow the connection tracking table has become confused and the packet is not even considered NEW, but with incorrect flags, nor is it considered part of the existing connection.

Consider a very basic iptables equivalent of what ufw is doing. Two scripts, one for clearing the rule set and one for creating it:

#!/bin/sh
FWVER=0.01
#
# clear_firewall_min 2018.08.10 Ver:0.01
#       clear iptables minimum.
#       Currently for this question:
#       https://askubuntu.com/questions/1059781/ufw-allows-22-for-ipv4-and-ipv6-but-ssh-disconnects-when-enabling
#
echo "Loading clear_firewall_min version $FWVER..\n"

# The location of the iptables program
#
IPTABLES=/sbin/iptables

#Set some stuff
#
EXTIF="ens5"
UNIVERSE="0.0.0.0/0"

#Clearing any previous configuration
#
echo "  Clearing any existing rules and setting default policies.."
$IPTABLES -P INPUT ACCEPT
$IPTABLES -F INPUT

# Reset all IPTABLES counters
$IPTABLES -Z

#sleep 10

echo clear_firewall_min $FWVER done.

And:

#!/bin/sh
#
# test_firewall 2018.08.13 Ver:0.01
#       Minimum version of most basic iptables firewall.
#
# test_firewall 2018.08.09 Ver:0.01
#       Most basic iptables firewall.
#       Currently for this question:
#       https://askubuntu.com/questions/1059781/ufw-allows-22-for-ipv4-and-ipv6-but-ssh-disconnects-when-enabling
#

#sleep 50

# The location of the iptables program
#
IPTABLES=/sbin/iptables

#Set some stuff
#
EXTIF="ens5"
UNIVERSE="0.0.0.0/0"

#Clearing any previous configuration
#
#echo "  Clearing any existing rules and setting default policies.."
$IPTABLES -P INPUT DROP
$IPTABLES -F INPUT

# loopback interfaces are valid.
#
$IPTABLES -A INPUT -i lo -s $UNIVERSE -d $UNIVERSE -j ACCEPT

$IPTABLES -A INPUT -i $EXTIF -p tcp -m conntrack --ctstate INVALID -j LOG --log-prefix "IINVALID:" --log-level info
$IPTABLES -A INPUT -i $EXTIF -p tcp -m conntrack --ctstate INVALID -j DROP
$IPTABLES -A INPUT -p tcp ! --syn -m conntrack --ctstate NEW -j LOG --log-prefix "NEW TCP no SYN:" --log-level info
$IPTABLES -A INPUT -p tcp ! --syn -m conntrack --ctstate NEW -j DROP
$IPTABLES -A INPUT -i $EXTIF -m conntrack --ctstate ESTABLISHED,RELATED -j ACCEPT
$IPTABLES -A INPUT -i $EXTIF -p tcp -m conntrack --ctstate NEW --dport 22 -j ACCEPT

echo "test_firewall_min $FWVER done..." >> /dev/kmsg

sleep 3

Resulting in these packets counts after a clear/load cycle with an ssh session that was started after a load cycle:

doug@s17:~$ sudo iptables -v -x -n -L
Chain INPUT (policy DROP 3 packets, 220 bytes)
    pkts      bytes target     prot opt in     out     source               destination
       0        0 ACCEPT     all  --  lo     *       0.0.0.0/0            0.0.0.0/0
      35     6388 LOG        tcp  --  ens5   *       0.0.0.0/0            0.0.0.0/0            ctstate INVALID LOG flags 0 level 6 prefix "IINVALID:"
      35     6388 DROP       tcp  --  ens5   *       0.0.0.0/0            0.0.0.0/0            ctstate INVALID
       0        0 LOG        tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:!0x17/0x02 ctstate NEW LOG flags 0 level 6 prefix "NEW TCP no SYN:"
       0        0 DROP       tcp  --  *      *       0.0.0.0/0            0.0.0.0/0            tcp flags:!0x17/0x02 ctstate NEW
       9      680 ACCEPT     all  --  ens5   *       0.0.0.0/0            0.0.0.0/0            ctstate RELATED,ESTABLISHED
       0        0 ACCEPT     tcp  --  ens5   *       0.0.0.0/0            0.0.0.0/0            ctstate NEW tcp dpt:22

Chain FORWARD (policy ACCEPT 0 packets, 0 bytes)
    pkts      bytes target     prot opt in     out     source               destination

Chain OUTPUT (policy ACCEPT 12 packets, 1408 bytes)
    pkts      bytes target     prot opt in     out     source               destination

Notice the 35 invalid packets as I typed on the crippled ssh session terminal, and before PuTTY terminated.

Why did this stop working, it used to work?

Because this is 100% repeatable, a kernel bisection was relatively easy, just time consuming. The results were:

4d3a57f23dec59f0a2362e63540b2d01b37afe0a is the first bad commit
commit 4d3a57f23dec59f0a2362e63540b2d01b37afe0a
Author: Florian Westphal <fw@strlen.de>
Date:   Fri Jul 28 11:22:04 2017 +0200

    netfilter: conntrack: do not enable connection tracking unless needed

    Discussion during NFWS 2017 in Faro has shown that the current
    conntrack behaviour is unreasonable.

    Even if conntrack module is loaded on behalf of a single net namespace,
    its turned on for all namespaces, which is expensive.  Commit
    481fa373476 ("netfilter: conntrack: add nf_conntrack_default_on sysctl")
    attempted to provide an alternative to the 'default on' behaviour by
    adding a sysctl to change it.

    However, as Eric points out, the sysctl only becomes available
    once the module is loaded, and then its too late.

    So we either have to move the sysctl to the core, or, alternatively,
    change conntrack to become active only once the rule set requires this.

    This does the latter, conntrack is only enabled when a rule needs it.

    Reported-by: Eric Dumazet <edumazet@google.com>
    Signed-off-by: Florian Westphal <fw@strlen.de>
    Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

Link to the entire commit.

How to revert to the expected behavior?

After disabling ufw or clearing the iptables rules set, create a new SSH session. It will survive a subsequent ufw enable, but might be subject to a random drop out at some point.

This issue will be taken upstream at some point, via the related e-mail list.

EDIT: upstream e-mail thread (contains a work around). Workaround copied here:

echo 1 | sudo tee /proc/sys/net/netfilter/nf_conntrack_tcp_be_liberal

EDIT 2: upstream proposed patch , which I have tested and reported back.

EDIT 3: 2018.11.06: This has stalled upstream, and I haven't had time to pester them. I'll try to get back to it soon.

EDIT 4: 2019.03.17: I can not reliably reproduce this issue with kernel 5.0.


The solution was given in a comment by GabrielaGarcia:

  Your phone uses MTP to enable mounting it's internal memory in a USB connect PC. This has to be enabled in the phone itself. Connect the cable then go to the dropdown menu in your phone, tap USB connection and choose the proper option.

– GabrielaGarcia Feb 6 at 13:51


GLVis: Linker error "undefined reference to symbol 'XGetWindowAttributs'"

The problem lies in an old environment variable that is no longer used in Ubuntu 18.04 LTS, called $X11_LIB_DIR. That doesn't evaluate to anything, and breaks the mpicc compiler when -L is used.

See below:

mpicxx -O3 -I../mfem -I../mfem/../hypre-2.10.0b/src/hypre/include -DGLVIS_MULTISAMPLE=4 -DGLVIS_MS_LINEWIDTH=1.4 -I/usr/include -DGLVIS_USE_LIBPNG -DGLVIS_USE_FREETYPE -I/usr/include/freetype2 -o glvis glvis.cpp -Llib -lglvis -L../mfem -lmfem -L../mfem/../hypre-2.10.0b/src/hypre/lib -lHYPRE -L../mfem/../metis-4.0 -lmetis -lrt -L -lX11 -lGL -lGLU -lpng -lfreetype -lfontconfig -lpthread

Notice the random "-L" before "-lX11"?

It should be this:

mpicxx -O3 -I../mfem -I../mfem/../hypre-2.10.0b/src/hypre/include -DGLVIS_MULTISAMPLE=4 -DGLVIS_MS_LINEWIDTH=1.4 -I/usr/include -DGLVIS_USE_LIBPNG -DGLVIS_USE_FREETYPE -I/usr/include/freetype2 -o glvis glvis.cpp -Llib -lglvis -L../mfem -lmfem -L../mfem/../hypre-2.10.0b/src/hypre/lib -lHYPRE -L../mfem/../metis-4.0 -lmetis -lrt -lX11 -lGL -lGLU -lpng -lfreetype -lfontconfig -lpthread

So, to fix this, change line #121 in makefile to read:

GL_LIBS = -lX11 -lGL -lGLU


apt-get doesnt download files from NFS location

deb-file is mainly used for CDROMs, so downloading them into a cache makes no sense.

Use deb-copy instead.

Source: $ man sources.list


How to install pip for Python 3.6 on Ubuntu 16.10?

This answer assumes that you have python3.6 installed. For python3.7, replace 3.6 with 3.7. For python3.8, replace 3.6 with 3.8, but it may also first require the python3.8-distutils package.

Installation with sudo

With regard to installing pip, using curl (instead of wget) avoids writing the file to disk.

curl https://bootstrap.pypa.io/get-pip.py | sudo -H python3.6

The -H flag is evidently necessary with sudo in order to prevent errors such as the following when installing pip for an updated python interpreter:

  The directory '/home/someuser/.cache/pip/http' or its parent directory
  is not owned by the current user and the cache has been disabled.
  Please check the permissions and owner of that directory. If executing
  pip with sudo, you may want sudo's -H flag.

  The directory
  '/home/someuser/.cache/pip' or its parent directory is not owned by the
  current user and caching wheels has been disabled. check the
  permissions and owner of that directory. If executing pip with sudo,
  you may want sudo's -H flag.

Installation without sudo

curl https://bootstrap.pypa.io/get-pip.py | python3.6 - --user

This may sometimes give a warning such as:

  WARNING: The script wheel is installed in '/home/ubuntu/.local/bin'
  which is not on PATH.   Consider adding this directory to PATH or, if
  you prefer to suppress this warning, use --no-warn-script-location.

Verification

After this, pip, pip3, and pip3.6 can all be expected to point to the same target:

$ (pip -V && pip3 -V && pip3.6 -V) | uniq
pip 18.0 from /usr/local/lib/python3.6/dist-packages (python 3.6)

Of course you can alternatively use python3.6 -m pip as well.

$ python3.6 -m pip -V
pip 18.0 from /usr/local/lib/python3.6/dist-packages (python 3.6)


trying to overwrite '*', which is also in package faenza-icon-theme 0.8

What's happened is that when you updated, it tried to install an update of the dockmanager, but a theme package you installed previously has done naughty things and replaced one of the dockmanager's files.

To fix you need to do the following:

sudo apt-get purge faenza-icon-theme

Then try and reinstall your dockmanager, you also need to report to the maintainer of faenza-icon-theme that he's made a broken package and he should fix it as soon as possible. Basically he needs to make it so that it doesn't replace files from other packages.


The problem with this version is that the program tries to run the file /bin/unpack200 which does not exist. However, the file /usr/bin/unpack200 does exist. This is due to the fact that this file is in different places depending on the architecture of the machine used - if it is 32bits, it is in one place, if it is 64bits, it is in the other.

I am having this problem because the file was made to run on a 32bit architecture but I am using a 64bits machine.

Therefore to fix this problem one must install 32bits libraries. To do so just type: sudo apt-get install ia32-libs.

Source:

http://forums.visual-paradigm.com/posts/list/2501.html


Unable to swap telex and vin on ubuntu 13.10 (ibus error)

Install the ibus-m17n package

$ sudo apt-get install ibus-m17n

Restart ibus

$ ibus restart

Go to System Settings > Text Entry, click the plus sign (+) to add a new input source, select "Vietnamese (vni (m17n)) then you're good to go.


How does Ubuntu determine what updates a user needs?

I think you need to step back a little. I don't think you understand how package management works in Ubuntu. I'll have a stab at explaining it at a high level —as to not write a whole book on the subject— but still cover your questions.

Each Ubuntu release has its own set of online package repositories.
A package repository is (essentially) just a directory with a pile of package files and a release file that lets you see what packages versions it contains
The "frozen" state of the package versions doesn't mean they never get updated. Maintainers try to leave packages on the same major version as at release, but security patches do get backported. And there are exceptions to this, Firefox being the obvious one, but I won't get too bogged down in the politics here.
When an security issue arises and something can be patched, the maintainer applies that patch to the version of software being used in that version of Ubuntu —for each supported version of Ubuntu— and builds packages for them, uploads them to the repo and the release file is updated.
Ubuntu systems can then (via Apt, the package manager) download these updated release files, see which packages can be updated and can then download and install the updates.
The installer will also offer to download these updates while it's installing. The first proper run of Ubuntu can be using fully updated software.

That should give you some sort of idea of the process. There's a ton of stuff happening behind the scenes but as I said, I wanted to avoid writing a book about this here.

The "patch history" and difference between ISO and current aren't really something exposed to the user. Ubuntu will just try to get the latest in the repo and the package maintainers take care of the rest. That said, you can see the package changelogs for some packages with (eg) apt changelog gnome-shell.


How to view a particular unicode character?

The strange box like character filled with 0B5F indicates that the character being referenced is indeed U+0b5f, but the font doesn't support it.

Try changing the font you're using in gedit to a font that does support Oriya symbols

Menu > Edit > Preferences > TAB(Font & Color) > Editor Font


cc is an alias for the GNU C compiler (gcc). You can install it as follows:

 sudo apt install gcc

If, for some reason, the gcc compiler is already installed, but the symbolic link /usr/bin/cc is missing, you can also do:

 make CC=gcc


You can automatically export them when you close the browser.
Go to about:config and set browser.bookmarks.autoExportHTML to true.
Another way would be online not with an HTML file using the Firefox Sync: Settings->Sync.


Ok I found a way around if someone got the same issue:
- Disable the autoconnect checkbox for 'wifi0' in EditConnections->wifi0->Edit->General


How do I get videos on some streaming sites to play

Try installing ubuntu-restricted-extras and more codecs:

sudo apt install libdvdnav4 libdvdread4 gstreamer1.0-plugins-bad gstreamer1.0-plugins-ugly libdvd-pkg
sudo apt install ubuntu-restricted-extras

Close and re-open Firefox to so it can see the newly installed codecs and you should be able to view videos that previously wouldn't play.

If you are still unable to view the content (assuming it's even real content, many "streaming" sites are fake and don't actually host content) press F12 and look at the Network tab in Firefox to see which files are loading. If any of them are video files you can try to download them manually and play them with VLC.


Should i update via software updater after upgrading kernel?

As long as the kernel is the newest version it will be listed first in GRUB's boot list. In Ubuntu the kernel will not be replaced by the new one. So even if the updater brings the 3.13 in your system (reportedly) the 3.12 kernel will still remain.

You have to know that GRUB boot-loader automatically lists the newest kernel first and this depends on the number/version/upload number/ of the kernel.

So 3.11 considered as older than 3.12 and except that will never be replaced, as it is newest it will be listed first in GRUB menu.

Although from the version I can assume that you are using a mainline kernel, read here about mainline kernels.

  And is there any way to put software updater get me updates for
  3.12.4?

As far as I know, no. You must update these unofficial kernels by yourself.


Is there module-esound-protocol-tcp on 19.10

In previous Ubuntu versions this file was a part of pulseaudio-esound-compat package (up-to 18.04 LTS). The source code base for it is pulseaudio.

You have to open software-properties-gtk and enable Source Code here first.

Then you have to get all necessary build-dependencies with sudo apt-get build-dep pulseaudio.

Then get the source package:

cd ~/Downloads
apt-get source pulseaudio

And then configure the source code with --enable-esound and compile new version of package.

But better way is to simply reinstall Ubuntu 18.04 LTS and use it for another 3 years.


dvips: How to get correct fonts for eps (encapsulated postscript)?

I have had similar problems with xfig fonts. I have only a 13.04 system here, will check later on a 13.10 at home. TeX (and dvips) mappings for Courier in my system are:

(0)asus-romano:~/personal/archivio/Tricks% wajig whichpackage /usr/share/texlive/texmf-dist/fonts/vf/adobe/courier
texlive-fonts-recommended: /usr/share/texlive/texmf-dist/fonts/vf/adobe/courier

So it seems that the package is texlive-fonts-recommended, which you should have.

Have you tried to convert the eps to pdf manually with something like epstopdf (probably it will give the same error as you have)? Can you see the .eps files correctly in evince or gs?

Another try could be to install the package gsfonts-x11 which, in /etc/X11/fonts/Type1/gsfonts-x11.alias, has definitions for the two fonts you have errors for (at least this could make tgif work --- it does in my 13.04).


How to enable USB 3 for HP EliteBook Intel Core i7?

USB3 requires 4 things to operate at USB3 speeds:

1) USB3 support in your BIOS and Operating System

2) USB3 ports with blue ceramic in the center of the USB port

3) USB3 cable with blue ceramic in the center of the USB plug ends

4) USB3 device with blue ceramic in the center of the USB port

Update:

If your specific model # is 1040 G3, there's a recent BIOS update that you may wish to look into and install...

http://h20565.www2.hp.com/hpsc/swd/public/readIndex?sp4ts.oid=9789251&swLangOid=8&swEnvOid=4192


How can I make lcms available to imageinfo (via imagemagick)?

Turns out the issue was that I have previously built imagemagick from source (and forgot about it), so when I ran convert -list configure | grep 'DELEGATES\|LIBS' it was showing output from imagemagick installed from repositories while imageinfo --iccname test.jpg was using imagemagick that I built from source which did not have lcms support.


There is a setting for that!

Right click on your desktop and choose "Configure Desktop..."

Click the "Mouse Actions" tab.

Next to "Middle-Button", use the drop down menu to select a different action.  You can also click the - button to remove the action.

This setting only affects the middle mouse button behavior when you click on your desktop, so it does not affect your ability to use the middle mouse button to paste when using applications.


Why am I getting Error: need a single repository as argument for sudo add-apt-repository ppa: paolorotolo / android-studio

You have spaces in the repository name. It should be:

sudo add-apt-repository ppa:paolorotolo/android-studio


How do I boot Ubuntu Cloud images in vmware?

This answer is based on the NoCloud README from CloudInit and gives you cloud-init on VMWare player.

Create the file "meta-data", using "localhost" as a guaranteed-to-resolve hostname to avoid DNS timeouts that make sudo take ages in a local hypervisor environment:

local-hostname: localhost

Create the file "user-data" file for CloudInit info. This one sets password to ubuntu, and asks me to change it on first login:

#cloud-config
password: ubuntu

Generate seed.iso from these files:

genisoimage -output seed.iso -volid cidata -joliet -rock user-data meta-data

Attach "seed.iso" to the VM before first boot (set it to connect on start), and when grub appears, also add this kernel parameter for the first boot:

ds=nocloud-net

The machine will boot and configure itself.  For future boots, we need to edit edit /etc/default/grub and run sudo update-grub to tell it we are not in EC2 (no cloud metadata service):

GRUB_CMDLINE_LINUX_DEFAULT="console=ttyS0 ds=nocloud"


redshift can not find geoclude2, after ubuntu 17 update

Two Complementary solutions:

1: Edit GeoClue's config to allow redshift

Append the following lines to /etc/geoclue/geoclue.conf by running:

sudo nano /etc/geoclue/geoclue.conf

[redshift]
allowed=true
system=false
users=

2: Edit or create RedShift's config with manual options.

Example of a manual config, for Copenhagen, Denmark. See Redshift homepage for an additional config example. Change the latitude and longitude for you location.
nano ~/.config/redshift.conf

[redshift]
temp-day=6500
temp-night=3700
location-provider=manual

[manual]
lat=55.7
lon=12.6

To Test

In a terminal run kill $(pgrep '[r]edshift*') && redshift -t 3600:3600 to kill the current instances and run redshift at 3600k temp. Over a few seconds the screen should adjust. If this works ctrl+c to interrupt the current redshift instance. Edit the redshift config to your desired settings. Restart redshift with the new config by running redshift-gtk & disown in a terminal.


I installed Ubuntu on my laptop but why can't I get any sound?

It's most likely due to which sound device is selected for play through.

Left click on the speaker at the top right of the screen (assuming unity desktop) and you'll find Sound Settings... Click that.

After clicking on Sound Settings... the following screen will load:

Notice Play sound through on the left side of the Output Tab. Based on your explanation you'll likely find that an HDMI device is selected. Select the device you'd like to hear sound through and test the sound to verify it works.


Running app from the SDK to a nexus 4 phone produces ssh_exchange_identification: Connection closed by remote host error

Recent changes made to the Ubuntu SDK have eliminated this problem for me.


How to remove a specific package from dependency list of another package?

Those packages still use qt4 that is why they want to be removed, they depend on it.

There are many packages that still use qt4 for there interface, just because qt5 is  available, it does not make qt4 obsolete, you can have both without issue.

I would recommend you keep qt4 as you may face issues with other applications that use qt4 and not qt5down the line.

Why do some packages still use qt4?

It is a lot of work to update your interface to a new language, as Ubuntu can support both versions at the same time and the difference to the end user is minimal, it is simply not a priority to update it with such a superficial update.


How do stop Ubuntu 20.04 from upgrading to the 5.8 hwe kernel?

It is easy to stop Ubuntu 20.04 from installing the 5.8 kernel.
Remove HWE meta packages by running:
sudo apt remove linux-{image,headers}-generic-hwe-20.04
sudo apt install linux-generic

If you also remove the already installed 5.8 kernel packages, it'll stick with the 5.4 kernels. They will get updates (bug fixes and security) till the end of life of the 20.04 release.


Does Ubuntu encrypt the home folder by default?

Under the default settings your home folder is not encrypted.


13.04 system UI fonts subbed with random serif font

See if this applies to your case.  It fixed the font spacing problems I was having in Gnome Terminal and Gvim.

Fonts corrupted, all look the same

I used Syanptic to determine the unidentified library.  The following cleared it up for me.

$ sudo apt-get purge libpango1.0-common pango-graphite


Got HP 255 with Ubuntu 12.04 pre installed - how to add dual boot with Mint Debian?

I don't know enough details, nor do I have the patience, to go into details, but having installed many simultaneous versions of various distros to try, and often discard, I can tell you that's it's both easy and dangerous, not necessarily in that order.

The way to do it is to use a live CD or USB distro (so the system on the disk won't be mounted), and make room for a new partition big enough for a new installation.  The size depends on how serious you want it to be, but usually 20 - 30 GB (or less) is plenty. You can also skip this and let the install do the partitioning, but in my experience, it often doesn't do a good job, or is not that easy to understand.  But I'm sure it can be done.

However you do it, you need to be aware of the fact that, by default, the newest installation will modify GRUB, the bootloader, to boot into the new system, and if you were to delete the new system, your old one won't boot without some TLC.  It's not really serious, but you would be forced to learn about how GRUB works a little, which isn't that easy for the faint of heart.

If you are willing and able to learn, you won't break your laptop.  But if not, you will think you have broken it, and for many people, that is the same thing.  Personally, I learn by destroying, so I often just forge ahead and do things that put me in the deep end, but you may not be that type of person.  But once you learn how things work, you will truly control your system, rather than vice versa...  well, more or less. :-)

If you proceed, make sure you can boot from a live CD and get internet access.  At least that way, you can get back here to ask questions if you have problems.


How can I make Ubuntu mouse sensitivity exactly the same as in Windows?

You can easily set it according to your needs in
System Settings → Mouse and Touchpad,  as shown in the image. Try to set the Acceleration properly .


Is it possible to manually define the usable space on my laptop's trackpad?

Not sure if this works on all touchpads (I think it should work on Synaptics and ALPS), but you could try and edit your xorg.conf and add

  Option "AreaBottomEdge" "XXX"

See Ubuntu manpages for more info about the Synaptics driver options.

  Option "AreaBottomEdge" "integer"

  Ignore  movements,  scrolling and tapping which take place below
  this edge.  The option is disabled by default and can be enabled
  by  setting the AreaBottomEdge option to any integer value other
  than zero. Property: "Synaptics Area"

You can also try it live by running synclient in terminal (Ctrl+Alt+T) with options:

  # synclient -l

to list current options and

  # synclient AreaBottomEdge=XXX

to change the settings temporarily. When you find the right XXX edit your xorg.conf.

See also synclient manpages.


Maybe something like...

A question

How to run a script with the root rights (so only the root can stop it) on startup ?

Possible answers

A) The Upstart /1/ can run scripts/programs with root rights during the boot.

B) You could use existing scripts to start your own script. The Ubuntu Resolution wiki /2/ has an example how to set xrandr commands in kdm/gdm startup scripts.

Earlier(Kubuntu Forums): "FAQ: Autostart / Autorun, Periodic run" /3/.

Links

http://upstart.ubuntu.com/
https://wiki.ubuntu.com/X/Config/Resolution
http://kubuntuforums.net/forums/index.php?topic=3117269.0


Ubuntu 12.04 LTS: Need a way to recover from a system freeze I encounter often (deleting folders)

This happens to me often. After Ctrl-Alt-F2, I do this at full screen terminal

sudo service lightdm restart

This brings me back to login and saves a full restart.


Linking IDE with right compiler for ARM cross compiling

There is a good article on this here:

http://derekmolloy.ie/beaglebone/setting-up-eclipse-on-the-beaglebone-for-c-development/


install new kernel produce the message "No space left on device" although there is free space

You're having an inode problem.  You probably have many small files somewhere that is using a very small amount of space.  Each of the files are using up your inodes.

You can get your inode count with this command:

$ df -i

Check out this link to help you to locate where you inodes are being used:
https://stackoverflow.com/questions/347620/where-are-all-my-inodes-being-used


Why does the update process remove files?

I suggest avoiding 'normal update manager' (WTI) and use CLI which will let you control this.

$ sudo apt-get update
$ sudo apt-get upgrade

Or possibly

$ sudo synaptic

When a brain-free automatic whatever-the-heck-it-is GUI consistently does something you don't want, use your Linux skills and don't behave as if you own a Macintosh.


Problem using Windows Installer for Ubuntu Desktop

Download the ISO from this page

Place it in the same directory as wubi.exe and then execute wubi.exe.

Good luck.


Both eclipse and flash are available in the repositories.

If you use the Ubuntu Software Center program or synaptic (for older versions of Ubuntu) to install the software, it will take care of it all for you, and will make sure the software is kept up to date.  It is recommended to use them unless the software you need is unavailable.


Upgrading wpa_supplicant to 2.6 manually on Ubuntu 17.10

If you want to upgrade your wpa_supplicant from current version to 2.6, refer the link below....

The instructions given in this link is for ubuntu 16.04, but i tried them on ubuntu 17.10 as well and so far no problem arised. Still try them at your own risk.

i'll be not responsible for any bad effects.(although which is not the case for me.it worked well without any errors at all).

if your going to try them..i suggest you to use 'sudo -s' and login as root user. then later it will come in handy when you execute 'cd /tmp' which is in the root dir. if not it will give the error directory not found.

link : http://www.linuxtopic.com/2017/08/compile-wpasupplicant-ubuntu.html

Edit:

I added below the necessary information also available on above link for the use of anyone, in case if the link may not functional anymore....

1) Need to install few dependencies required by wpa_supplicant

sudo apt install libssl-dev build-essential checkinstall  pkg-config

sudo apt install dbus libdbus-1-dev libdbus-glib-1-2 libdbus-glib-1-dev libreadline-dev libncurses5-dev

sudo apt install libnl-genl-3-dev libnl-3-dev

2) Then go to the root directory & then go to tmp folder

cd /

cd tmp

3) Download wpa_supplicant source package

wget https://w1.fi/releases/wpa_supplicant-2.6.tar.gz wpa_supplicant2.6.tar.gz

4) Extract  wpa_supplicant2.6.tar.gz

sudo tar xvf  wpa_supplicant2.6.tar.gz

if this command returns a error, make sure that the name of the downloaded tar file and the name in the command are same. if the downloaded tar file's name is different from the file name in the command, it will not able to extract the file.

5) Go in to extracted wpa_supplicant folder.

cd wpa_supplicant2.6

Again if returns a error check whether the folder name is correct.

6) Create a build configuration file that should work for standard WiFi setups by running the following command.

cat > wpa_supplicant/.config << "EOF"
CONFIG_BACKEND=file
CONFIG_CTRL_IFACE=y
CONFIG_DEBUG_FILE=y
CONFIG_DEBUG_SYSLOG=y
CONFIG_DEBUG_SYSLOG_FACILITY=LOG_DAEMON
CONFIG_DRIVER_NL80211=y
CONFIG_DRIVER_WEXT=y
CONFIG_DRIVER_WIRED=y
CONFIG_EAP_GTC=y
CONFIG_EAP_LEAP=y
CONFIG_EAP_MD5=y
CONFIG_EAP_MSCHAPV2=y
CONFIG_EAP_OTP=y
CONFIG_EAP_PEAP=y
CONFIG_EAP_TLS=y
CONFIG_EAP_TTLS=y
CONFIG_IEEE8021X_EAPOL=y
CONFIG_IPV6=y
CONFIG_LIBNL32=y
CONFIG_PEERKEY=y
CONFIG_PKCS12=y
CONFIG_READLINE=y
CONFIG_SMARTCARD=y
CONFIG_WPS=y
CFLAGS += -I/usr/include/libnl3
EOF

7) If you use WPA Supplicant with NetworkManager 1.8.0, add the following options to the WPA Supplicant build configuration(OPTIONAL)

cat >> wpa_supplicant/.config << "EOF"
CONFIG_CTRL_IFACE_DBUS=y
CONFIG_CTRL_IFACE_DBUS_NEW=y
CONFIG_CTRL_IFACE_DBUS_INTRO=y
EOF

8) Compile & create package

cd wpa_supplicant

make

9) Install Wpa_supplicant & create wpa_supplicant 2.6 package

checkinstall

This command will carry on with the installation and make a note of that the user will be required to press ENTER in several locations to proceed with the installation.

10) Finally package created check on same directory and wpa_supplicant version check

ls wpa-supplicant*

wpa_supplicant -v

Done! if everything went smoothly it should return that, the wpa_supplicant version is 2.6


Increase persistent file size to greater than 4 gigabytes

Take a look at http://www.pendrivelinux.com/create-a-larger-than-4gb-casper-partition/. The tutorial is for an older version of Ubuntu but works fine for 10.10 and 11.04.

The reason why a separate partition must be created  is because the USB creator only makes one partition by default (FAT32 filesystem). Onto that partition it copies the CD or ISO contents and creates a persistence file (ext2 formated) called casper-rw. Since FAT32 can't hold larger then 4GB files the persistence file can't be any larger then 4GB.


Wifi problems on Ubuntu dual boot windows10; Tried to fix, now it doesn't work on windows 10 or Ubuntu

It turns out that this was actually 2 separate issues. Today an Ubuntu update dropped, and now my WiFi works just fine. As for Windows 10 it appears only not to work on my home network ( No other devices are experiencing this ), this I will look into separately, since it is not related to Ubuntu.


Gparted error on sda3, system reserved is normal as that is required to be unformatted, but then gparted throws an error. The error on sda4 is only normal if you can directly boot Windows and then that says your have fast startup still on. But error on ext4 partition, sda8, says you may need fsck.Run both of these commands on sda8. Ubuntu 14.04 is not booting normaly after a manual hard boot


Unable to add / update repositories in lubuntu 18.04

Screenlets does not provide version for Ubuntu 18.04, in fact it has not been updated since 16.10 (Yakkety).
Abandon screenlets
This will remove Screenlets ppa, effectively get rid of the problem altogether.
sudo add-apt-repository --remove ppa:screenlets/ppa
sudo apt update

Use old 16.04 source
If you wish to keep using screenlets, a quick workaround would be using the 16.04 (Xenial) source to install Screenlets.
sudo sed -i 's/bionic/xenial/g' /etc/apt/sources.list.d/screenlets-ubuntu-ppa-bionic.list
sudo apt update

There'll be no error produced, you can now install package provided from screenlets ppa.
Note that I have not tested this method because it's not something I want to (have to un-)do on my machine

As a side note, you may want to refer to this nice tutorial which explain in depth how to successfully install Screenlets on Ubuntu 18.04 (and 20.04 !).


Ubuntu 12.04 graphics crashing when GVIM opens TEX files

A quick search shows me that such module is in the repositories, you could try installing it and see if it makes the difference:

sudo apt-get install libgail-3-0


How to install drivers to recognize my Intel HD 3000 graphics card? (on Ubuntu 14.04LTS)

Ubuntu 14.04 already comes with the latest graphics stack, so you don't need the installer.
You're up to date :)


Ubuntu 19.10 login screen rectangles instead of letters

From the comments...

User had installed a theme/icon pack that caused the problem. Removed it and it's OK again.


I had same problem (NetBeans 8.1, Debian 8.1).

In /etc/fstab I removed "noexec" parameter in /tmp definition, remount /tmp and now it works.  (missing execution permission) ;)


Burg Custom Icons work only with specific themes

Interesting..... I didn't actually know that there was a specific place to put custom icons (or precisely, where it was XD).  I do know, however, that when I made custom icons for my BURG install (using Lightness) I just stuck them in with the rest of the icons under /boot/burg/themes/Lightness/somewhere and changed the file in there that came along with it (the changes you made, I think).

TL:DR Try making those text changes in the theme-specific folder instead in addition if applicable.


EXT4-fs (sda2): I/0 error while writing superblock

Try this:
Boot a live system (Your Ubuntu Budgie install media)
Open a terminal and run:
sudo umount /dev/sda2
sudo fsck -f /dev/sda2


how to create bootable USB drive (ubuntu)

The simplest way is to use GNU dd:

sudo dd bs=4M if=/path/to/ubuntu.iso of=/dev/sd<X> && sync

where <X> is your drive letter.


How do I terminate a 'Ping' without closing the command terminal window?

There are three options:

Manually interrupt the ping command using Ctrl+C, as described in @steeldriver's answer.
Use ping's "count" option (-c COUNT) to send exactly COUNT pings and then terminate automatically, as described in @bodhi.zazen's answer.
Use ping's "deadline" option (-w DEADLINE) to run for exactly DEADLINE seconds and then terminate automatically.

Of course you can combine the three options. If you pass both a "count" and a "deadline" option, ping will terminate as soon as the first event occurs. And Ctrl+C works always anyway.

Here's an example with a "count" of maximal 10 pings and a "deadline" of 5 seconds, but which got terminated manually using Ctrl+C after 3 pings (^C):

$ ping -c 10 -w 5 askubuntu.com
PING askubuntu.com (104.16.110.188) 56(84) bytes of data.
64 bytes from 104.16.110.188: icmp_seq=1 ttl=56 time=54.6 ms
64 bytes from 104.16.110.188: icmp_seq=2 ttl=56 time=52.5 ms
64 bytes from 104.16.110.188: icmp_seq=3 ttl=56 time=54.0 ms
^C
--- askubuntu.com ping statistics ---
3 packets transmitted, 3 received, 0% packet loss, time 2001ms
rtt min/avg/max/mdev = 52.582/53.733/54.611/0.850 ms


Ubuntu software center remove configuration files

There is no conflict involved in installing both Synaptic and the Ubuntu Software Center. If you need to use a feature of Synaptic, it is possible to do so without it interfering in any way with the Ubuntu Software Center.


sudo apt-get remove tex-common resolved the problem for me.


cannot login to ubuntu user account after setting LD_LIBRARY_PATH

With your script, you have overwritten the LD_LIBRARY_PATH with only one path.

Start the grub menu by holding down the left Shift key during system start
Select the entry Advanced … and start the Recovery mode
Select root
Remove the file
Press Ctrl-D and resume the boot process

For more information about LD_LIBRARY_PATH read this article.


The server booted, just the apache got stuck somewhere. Log in and check the /var/log/apache2/error-log file's content, you will have the answer about what was wrong.


How to configure up arrow to search the history?

Both methods below are almost equivalent, it just depends on which file you want to edit. I'd recommend .bashrc myself, as it doesn't involve editing a local copy of a system file.

If you experience any problems with this, please comment below so that it can be fixed.

Using ~/.bashrc

Edit ~/.bashrc with this command:

gedit ~/.bashrc

Add the following lines:

bind '"\e[A": history-search-backward'
bind '"\e[B": history-search-forward'

Save then close the file.
Execute this command in a terminal:

source ~/.bashrc

Using ~/.inputrc

Execute this command in a terminal:

cp /etc/inputrc ~/.inputrc

Edit the new ~/.inputrc file with this command:

gedit ~/.inputrc

Append these lines to the file:

"\e[A": history-search-backward
"\e[B": history-search-forward

References:

incremental history searching with .inputrc ?
In bash, how do I bind a function key to a command?


Same here! 30 minutes of digging and I found this:

$ apt-get download udev
$ sudo dpkg -i --force-confmiss udev_204-5ubuntu20.9_amd64.deb
$ sudo apt-get upgrade

Worked for me. For more info go to Dimitri's comment in Ubuntu's bug tracker.


Bookmark desktop in Nautilus on Ubuntu 17.10

My experience with 17.10 is that if you take the Desktop icon from the right hand pane of Nautilus and drag it to the lower bookmark pane, it will create a bookmark for it there. You don't seem to be able to create a bookmark in the upper bookmark area.

I store all my data in a Dropbox folder.  I therefore deleted built in folders such as Documents and Videos, as they contained nothing.  Their icons continued to remain in the upper bookmarks area, and the secondary click "Remove" function was greyed out.  However after I rebooted, the system seemed to become aware that the icons for Documents etc. were pointing at folders which no longer existed.  After a reboot, the "Remove" function worked.


Internet connection dropped after docker start

systemctl stop docker
iptables -t nat -F
ifconfig docker0 down
brctl delbr docker0
systemctl start docker


He used brightness-controller, didn't work perfectly but better than nothing, if you have a better answer, I'll upvote it and accept it.


How to install wine-stable in ubuntu 19.10

U can try installing kakaotalk messenger using Play on linux  a little buggy sometimes but it work


How does one go about installing flash 11 (64bit)?

Install Flash-Aid and run the extension Wizard. Flash-Aid allows to install Flash 64bit from Adobe Labs (32bit from repos and Chrome too), it removes conflicting plugins and apply performance tweaks. Additionally, it has a plugin update checker, so you can be notified about new beta versions.


Ubuntu prior to 18.04
Instead of disabling execution of the /etc/init.d/ondemand (as suggested by George) script you should use the this command
sudo update-rc.d ondemand disable

To make the init system not start the script, this is the recognized way of doing it! Disabling the exec permission (sudo chmod -x /etc/init.d/ondemand) might be overwritten if the package is updated.
Ubuntu 18.04+
Ubuntu relocated this script to ondemand.service which execute /lib/systemd/set-cpufreq; use this command to disable the service
~$ sudo systemctl disable ondemand
Removed /etc/systemd/system/multi-user.target.wants/ondemand.service.


Installing SHOUTcast on Ubuntu Server 12.04

Method 1:

The file is on your USB stick. I suppose you plugged it into your computer. So you need first to know the name of your USB stick. For this, run this command on Terminal:

ls /media

This will give display the name of your USB stick, for example: usb1234

To copy your file, run this command on your Terminal:

cp /media/usb1234/sc_serv2_linux_x64_11_29_2013.tar.gz .

This will copy sc_serv2_linux_x64_11_29_2013.tar.gz to where you are running the commands on Terminal (continue reading above).

tar -xzvf sc_serv2_linux_x64_11_29_2013.tar.gz

Running man tar on Terminal will give you the explanation of the options xzvf above:

 -x, --extract, --get
       extract files from an archive

 -z, --gzip, --gunzip --ungzip

 -v, --verbose
       verbosely list files processed

 -f, --file ARCHIVE
       use archive file or device ARCHIVE

This will extract the file above in the same folder where you opened the Terminal. By default, when you open Terminal you are on /home/your_user_session

If you do not know where you are then just type on Terminal:

pwd

Method 2:

The simplest way: if you are running Ubuntu 12.04 and over, then as soon as you plug your USB stick into the computer, it will be opened and you will find yourself within it, in which case you can view the data of your USB stick and copy what you want using the mouse :)

If it is not opened by default then be sure you plugged it correctly and click on the file browser where you will see the name of your USB stick displayed as above:

Click on the USB stick name and copy your file wherever you want. Then right click using the mouse on your file and click on Extract Here.

Method 3:

If sudo fdisk -l shows the presence of a USB stick but you can not access it then you have to mount it:

sudo mkdir /media/external

That creates the mount point in /media called /external in our case (you can choose an other name)

sudo mount -t vfat /dev/sdb1 /media/external -o uid=1000,gid=1000,utf8,dmask=027,fmask=137

That will mount the drie.

After you finish, you have to unmount the device by running:

sudo umount /dev/sdb1

Or:

sudo umount /media/external

Source.

Begueradj


Wireless connection drops then password rejected on 12.04

Looks like this is a bug with kernel 3.2.

This bug report shows more.

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/983025

I upgraded the kernel to 3.5, and now all is well.

Thanks for the help.


The side usb ports don't work on my Apple Wired Keyboard

This sounds like it might be a hardware problem. I've got an apple keyboard and the USB ports work fine. I know there can be problems with USB if there is insufficient power. Have you tried a different USB port or connecting the keyboard via a powered hub?


can't install or update any program, dpkg: error

open ternimal and type these one by one

sudo dpkg --configure -a

sudo apt-get -f install

sudo apt-get --fix-missing install

sudo apt-get autoclean

sudo apt-get clean

sudo apt-get autoremove

this should fix it.

Source


I've just found the solution for my similar issue here:

  These are the exact steps you need to follow to solve the emulator
  issue:

  Change directory:

$ cd ~/Android/Sdk/emulator/lib64/libstdc++

  Create symbolic link to library:

$ mv libstdc++.so.6 libstdc++.so.6.bak

  on the same directory:

$ ln -s /usr/lib/x86_64-linux-gnu/libstdc++.so.6

That should fix it! As soon as it was applied I've got the virtual device running.


ifdown  reports unknown interface when it exists!

Try

sudo ifconfig enx00051ba6daff down

I had the exact same problem and this worked. Here is the link I used.
https://ubuntuforums.org/showthread.php?t=1323646


Automating Linux (Like AutoHotKey for windows)

AutoKey can do everything you're asking for. You can find it in the Ubuntu Software Centre.


Create a .sh file and copy paste the contents.

vi file_name.sh

#!/bin/bash
xrandr --newmode "1280x1024_60.00" 109.00 1280 1368 1496 1712 1024 1027 1034 1063 -hsync +vsync
xrandr --addmode VGA1 1280x1024_60.00
xrandr --output VGA1 --mode 1280x1024_60.00

and save the file. Change the permissions.

  chmod +x file_name.sh

Now open dash. Search for "Startup Applications" and open it.

Click "Add" and browse for the file that you created earlier(file_name.sh) and add it.

Check this Q&A for detailed answered about adding a program to Startup Applications


Since USB is formatted with FAT32 filesystem, Can you mount it with this command?

$ sudo mount /dev/sdb1 /mnt

You may also refer to help for Mount in Ubuntu Documentation.


The problem of apt fix-broken install in Ubuntu

The package nvidia-cuda-toolkit depends on nvidia-cuda-dev. nvidia-cuda-dev contains the file /usr/include/cublas.h which is also in package libcublas-dev so only one of those two packages can be installed at the same time, and currently that's libcublas-dev.

So basically you can have either nvidia-cuda-toolkit or libcublas-dev but not both. Remove one of them.

It seems libcublas-dev is made for another distro or Ubuntu version and not compatible with Ubuntu 18.04.


Ralink Tech MT7601U Wireless Adapter on Xubuntu

I've found the solution (and it is not the one suggested by the message that appeared to me ten times to which I replied no, other ten times.. maybe I have overrated the community..).

I think this solution will work with Debian/Ubuntu/Xubuntu/Lubuntu (and similar) with Kernel version up to 4.4.x.y

Reading the README.md find inside the minidisc provided with the Adapter box I find out an unofficial driver here

According to the driver these USB devices are supported:

2955:1003
2955:1001
2955:0001
2A5F:1000
148F:760B
148F:7601
148F:6370
148F:7650

You can verify if driver it's suitable for your device by plugging in the adapter and launching lsusb

Now, to download and install the driver, follow these steps:

sudo add-apt-repository ppa:thopiekar/mt7601
sudo apt-get update
sudo apt-get install mt7601-sta-dkms

Install will end with some error incompatible-pointer-types and incompatible argument passed to a function.

Than the Adapter still not works, to workaround I have follow these steps:

1) Check your Kernel Version by launching uname --kernel-release

2) Download corresponding kernel source from Kernel Archive -> you will see a unordered list of Kernel Version -> click on corresponding version (Example: if you have 5.0.0-23-generic click v5.x/) -> from the next page search for the file linux-5.0.tar.xz -> download it

3) From archive unpack just folder drivers/net/wireless/mediatek/mt7601u

4) Find and Edit file phy.c. Find function mt7601u_init_cal (row 1116) and comment out call mt7601u_mcu_calibrate(dev, MCU_CAL_RXIQ, 0); (line from 1156 to 1161) as follows:

// ret = mt7601u_mcu_calibrate(dev, MCU_CAL_RXIQ, 0);
// if (ret)
// return ret;
// ret = mt7601u_mcu_calibrate(dev, MCU_CAL_DPD, dev->dpd_temp);
// if (ret)
// return ret;

5) Find function mt7601u_phy_recalibrate_after_assoc (row 587) and comment out call mt7601u_mcu_calibrate(dev, MCU_CAL_DPD, dev->curr_temp); (row 589) as follows:

void mt7601u_phy_recalibrate_after_assoc(struct mt7601u_dev *dev)
{
// mt7601u_mcu_calibrate(dev, MCU_CAL_DPD, dev->curr_temp);
   mt7601u_rxdc_cal(dev);
}

6) Open a terminal and go to mt7601u folder path

7) Build module by tiping:

make -C /lib/modules/$(uname -r)/build M=$(pwd) modules

8) If the Adapter is plugged in remove it and (from the same path) type:

sudo su
rmmod mt7601u (can output "module not loaded". if yes, ignore it and continue)
insmod ./mt7601u.ko

9) Insert device

10) Now Adapter should works but If you restart the pc you have to reload module again. Than to make change persistent till next kernel upgrade: backup original module and replace with compiled. To find out where is original module run modinfo mt7601u (view string filename: /lib/modules/_KERNEL_VERSION_/kernel/drivers/net/wireless/mediatek/mt7601u/mt7601u.ko).

10.1) If after reboot the Adapter is not recognized you have to follow these steps:

cd /etc/modprobe.d
ls

If you find a file named blacklist-mt7601u.conf remove it.

Then type nano /etc/modules and write a single line with module name mt7601u (without .ko)

reboot the system. Enjoy.

Hope helps... to solve the problem and to learn how to write a usefull problem solution..


Check $ uname -a

It is possible that the upgrade from 16.10 to 17.04 did not properly load the 4.10.x kernel. There is a scripting error that prevents the 4.10.x kernel from installing properly. If your uname -a shows the old 4.8.x kernel version. Then this is the case for you. The new code is not designed to work with the older kernel. And, among others, power management is a problem.

This issue is discussed on launchpad... HERE

Installing a newer kernel is not very easy. But, one way is to add the PPA for the lastest kernels into your Software Update ---> Other Software. I believe the PPA address is http://kernel.ubuntu.com/~kernel-ppa/mainline/ [Sorry that doesn't seem to be the correct listing - Can anyone add that here?]
After you add the PPA and exit Software Updates, the cache will rebuild. Then open software updater and the 4.10.x kernel should be among the updates listed.

If that doesn't work for you. Please search "install newer kernel". And, you will find much info on that.

OR you can trust this little tutorial and just do it manually. I am assuming a 64bit system here. If you are using a 32bit system, the "_amd64.deb" part of the filenames below should be changed to "_i386.deb"

First:

$ cd /tmp

Second enter:

$ wget \  <ENTER>
kernel.ubuntu.com/~kernel-ppa/mainline/v4.10/linux-headers-4.10.0-041000_4.10.0-041000.201702191831_all.deb \
    kernel.ubuntu.com/~kernel-ppa/mainline/v4.10/linux-headers-4.10.0-041000-generic_4.10.0-041000.201702191831_amd64.deb \
    kernel.ubuntu.com/~kernel-ppa/mainline/v4.10/linux-image-4.10.0-041000-generic_4.10.0-041000.201702191831_amd64.deb

Hit  after each line and when ALL of them are completed, wait for the download to complete and return you to your host prompt. Don't change directory. Stay where you are. And...

Then enter:

$ sudo dpkg -i linux-headers-4.10*.deb linux-image-4.10*.deb

Once finished, reboot. The new kernel should be confirmed by issuing

$ uname -a

You are now running the correct kernel for Ubuntu 17.04 :-D

---- Also. May I suggest ----

I found the above when I was looking for a solution to a "return from suspend' problem involving nVidia driver problems. I was also using 381.22 So, I also recommend that you consider dropping down to the 375.x version of Nvidia drivers listed in "Additional Drivers". 381.x is problematic when returning from suspend on some chipsets.

There is also a confirmed bug with nVidia when using the updater to upgrade from 16.10 to 17.04 that relates to nVidia adapters and prevents video from recovering from suspend mode when using the newer 381.22 driver. the explanation is at the same link as above.

To downgrade nVidia driver to 375.x;

$ sudo apt install --reinstall nvidia-375

Then select the 375.xx driver from "Additional Drivers" in "Software Updates". They "might" not appear in the list until you reboot.

I hope this helps with your problem.


can i change ubuntu 19.10 to 18.04.4 LTS?

It is impossible to downgrade from 19.10 to 18.04.3LTS. If you really want to revert it back, backup all your data and reinstall Ubuntu to the version you want. As a reminder, you should read properly the support dates before upgrade your Ubuntu.


How to time sync two systems in same network?

You can use NTP.  To install, if not installed, just press Ctrl+Alt+T on your keyboard to open Terminal. When it opens, run the command(s) below:

sudo apt-get install ntp

Once done, you can do:

ntpdate <machine_IP_address>

example: ntpdate 192.168.1.9

For more info, see Time Synchronisation with NTP


Firefox stuck opening rar files as videos

Try right clicking on the file in the File browser (Files or Nautilus), selecting 'Properties', then choose the 'Open with' Tab, find the program you want to to open the file with by default (I would guess you want to use 'Archive Manager', and then clicking on 'Set as default'. This should tell firefox (and any other application) which program to open the file with by default.


Why can't Xubuntu 12.04.2 connect to my hidden WPA/WPA2 personal protected wifi network?

It's been a long while since I took my PC networking classes (and I'm no expert), but it sounds odd that your computer sees a hidden network. Have you tried (just for giggles) re-enabling SSID broadcast on your router, connecting your computer to your network, and then disabling SSID broadcast again to hide your network and see if it retains the connection?


Ubuntu 17.10 WiFi: Internet stops working after some time

I have several suggestions that may help connectivity.

First, in your scan results, we see no fewer than six access points with the same name. In your wireless info, we see that your wireless device drops one instance and roams to another, looking for a better signal:

[ 8158.059001] wlp2s0: disconnect from AP <MAC 'ION@17th-Block' [AC1]> for new auth to <MAC 'ION@17th-Block' [AC8]>
[ 8158.064564] wlp2s0: authenticate with <MAC 'ION@17th-Block' [AC8]>
[ 8158.067518] wlp2s0: send auth to <MAC 'ION@17th-Block' [AC8]> (try 1/3)
[ 8158.070584] wlp2s0: authenticated

I suggest that you bind your wireless connection to the strongest of the nearby instances in Network Manager using the method I describe here: Ubuntu connect drops. Worked for a while then started dropping again

Next, I recommend that you turn off power saving in Network Manager; from the terminal:

sudo sed -i 's/3/2/' /etc/NetworkManager/conf.d/*

Finally, set your regulatory domain explicitly. Check yours:

sudo iw reg get

If you get 00, that is a one-size-maybe-fits-all setting. Find yours here: http://en.wikipedia.org/wiki/ISO_3166-1_alpha-2 Then set it temporarily:

sudo iw reg set IS

Of course, substitute your country code if not Iceland. Set it permanently:

sudo nano /etc/default/crda

Change the last line to read:

REGDOMAIN=IS

Proofread carefully, save (Ctrl+o followed by Enter) and close (Ctrl+x) the text editor.

Reboot and tell us if there is any improvement.


I have fixed this issue by reinstalling the unity-control-center.
sudo apt-get remove unity-control-center
sudo apt-get install unity-control-center


I have found the answer, just install fonts-noto.


Ralink RT3290 WiFi card not working on Ubuntu 16.04

Found the answer after two days, posting it here for others to find. This modified driver for Ubuntu 15.04 fixed the problem for me. Many thanks to the author! Those of you who, like me, are new to Linux, will appreciate how easy it is to install them.


Your all-in-one-router (effectively also DNS+DHCP+Switch, etc.) is just a 'relay' device in this. It needs another DNS server to relay your DNS queries to and this is called a recursive lookup. PCs can 'ask' these DNS queries either to your router, or they can talk to another one on the internet directly if you want to, e.g. 8.8.8.8 (one of Google's Public DNS service). It will then just bypass the router in DNS queries.

The router might see the queries passing, but unless it intercepts it, it will just happily pass that as all other traffic you send into the world via it.


"Device a170" shows that your distribution's lspci doesn't yet know the PCI ID of that device, so it's likely that the kernel driver does not know it either.

Consider using a more modern distribution, or at least update the kernel.


Why is caret/cursor invisible in mcedit in Xubuntu 16.04?

I have the same problem with Xubuntu 16.04.

The solution is to change xfce4-terminal's setting via Edit->Params->Colors->Cursor Color as you needed.


1- "The configuration file for sudo is /etc/sudoers. It should always be edited with the visudo command. visudo locks the sudoers file, saves edits to a temporary file, and checks that file's grammar before copying it to /etc/sudoers."

2- Automatic repetitive work is generally best done via a script, not a GUI.


You need to wrap colour codes in \[ and \]

PS1='\[\e[0;36m\]$ \w \[\e[m\]'

Also, PS1 is only relevant to your interactive shell, you don't need to export it to child processes.


how to use grep in a conditional search previous to a sed text replace command

Finaly I found the answer:

grep -lr -i -Z -e 'm:\\' * | xargs -0 sed -i 's/M:\\/K:\\/g'

I had to add the -Z to take care that every filename is read, and not the entire bunch in one long string.


How do I change the cursor and its size?

I would suggest you update your cursor theme and cursor size.

First in a terminal type:

sudo update-alternatives --config x-cursor-theme

Choose the number of the theme you want - e.g. 0 for DMZ-White

Changing the value here requires a reboot - a logout and login will not suffice.

Secondly, using dconf-editor (install using sudo apt-get install dconf-tools)

navigate to org.gnome.desktop.interface

change the cursor size to 24 and cursor theme to DMZ-White


You have a couple of options:

You can proceed with the installation without connecting to the Internet.

While it is recommended to be connected to the Internet when installing Ubuntu, installation while disconnected usually works just fine. Updates will not be downloaded during installation, but other than that, Ubuntu usually installs just fine.

After installing, when you boot into your newly installed Ubuntu system, you can update your system. You will likely be prompted automatically to do so. If not, open the Update Manager (type the first few letters of Update Manager into the dash and you'll be able to click the icon for it).

Even if you were connected to the Internet and installed updates while installing Ubuntu initially, there still might be other (typically less critically important) updates to install afterwards. So updating your system after installing it is a good idea, whether or not you are connected to the Internet when you install.
Since you're able to connect to the Internet after selecting Try Ubuntu, you can install Ubuntu while "trying" it.

There should be an Install Ubuntu icon on the desktop after you select Try Ubuntu. It should also appear in the Unity launcher (on the left side of the screen). If for some reason it doesn't appear in either place, you can open the dash (click the home button at the top of the launcher, or press the Super/Windows key) and search for it.

This is probably your better option, as you'll have all the (albeit modest) benefits associated with being connected to the Internet while installing Ubuntu.


Well, I don't think you gonna like the answer.

According to https://maas.ubuntu.com/docs/changelog.html cluster controllers have been deprecated and replaced by rack controllers. Cluster tab was removed and at least at this moment configuration can only be seen/modified by using CLI:

maas your-maas-profile rack-controllers read

Some of configuration could also be seen/modified in Networks tab https://maas.ubuntu.com/docs/rack-configuration.html#rack-configuration

Edit. Just few moments ago I have discovered you can actually view the status of controller in MAAS GUI > Nodes by clicking on Controllers:

I wonder myself how I have missed it out. Oh well, live and learn :)


Brightness controll not working in lenovo g580

Even I had the same problem. For brightness control edit the grub.cfg file like given below and reboot. Now u will be able to use the keys. Note: the code you need to edit is highlighted.

menuentry 'Linux Mint 13 Cinnamon 64-bit, 3.2.0-23-generic (/dev/sda6)' --class linuxmint --class gnu-linux --class gnu --class os {
    recordfail
    gfxmode $linux_gfx_mode
    insmod gzio
    insmod part_msdos
    insmod ext2
    set root='(hd0,msdos6)'
    search --no-floppy --fs-uuid --set=root 193c42e2-847f-42e9-9798-bca4c2b9597d
    linux   /vmlinuz-3.2.0-23-generic root=UUID=6304e339-3f61-4aac-be29-fbf7a252b37f ro **acpi_backlight=vendor**
    initrd  /initrd.img-3.2.0-23-generic
}


x11vnc - How can I allow only certain users to have a VNC session

You can use the -unixpw option to use the user's OS name/password to authenticate instead of a single shared VNC password.   The same option also allows you to specify a list of which users to allow.   There are also a couple of other variants of that option (-unixpw_nis & -unixpw_cmd) that offer more ways of hooking into the system security and doing something fancier.

The X11VNC command-line options page will give you a taste of how they work.


DHCP Server unknown lease. Device says "unable to obtain IP"

You have two subnet declarations in your configuration, but only one interface. This may be used in some instances, but usually you would match on some client identifier or similar discriminator to allow dhcpd to know which subnet to use.

You do not have any such discriminators as far as I can tell, and thus dhcpd does not know which subnet to use. This commonly leads to the somewhat imprecise error message that it's an unknown lease.

Remove the subnet declaration you do not use, which, according to your logs and configuration, is this:

subnet 192.168.3.0 netmask 255.255.255.0 {
  range 192.168.3.10 192.168.3.20;
}

Simply remove it or comment it out (prepend each line with # to comment it out), and restart dhcpd and test again.


It stops when you hang up the terminal.  Terminals don't necessarily have the concept of being closed.

With a terminal emulator program, there isn't anything real being hung up, but closing the emulator program triggers an emulated terminal hangup.  (More strictly: closing the master side of the pseudo-terminal device qualifies as terminal hangup on the slave side.)  Not all emulator programs have the notion of being closed.  The one that is built into the operating system kernel, providing the kernel's virtual terminals, cannot be "closed", for example.

With a real terminal, there is a serial port with a carrier detect line, and a real modem hangup that can occur if the dial-in user on the remote terminal hangs up the telephone connection.

This all dates back to the days of timesharing systems with remote terminals where users were billed for use.  If one accidentally lost one's telephone connection, one most certainly didn't want to be billed for programs still running, potentially until the next system restart.  Conversely, system administrators and other users didn't want programs still running and attached to now notionally free terminals that might be then assigned to other dial-in users.

A lot has changed since then.  BSD job control, for starters, inspired changes to the distribution of the hangup signal and the introduction of the notion of a session leader that is in charge of the jobs within a login session and whose death is considered to be a crushing blow to those jobs.  We've gained remote login over the Internet, and the idea of a GUI login session.  And terminal emulator programs have become so prevalent that people conflate them with the terminals that they are emulating.

But the fundamental idea remains that user processes are in the normal case terminated — somehow, even if through the mediation of a session leader — when their terminal session ceases.


There seems to be couple of discussion concerning this topic on JIRA :

The first one discussing how the message error isn't clear Bzip2 error message isn't clear and so there is not resolution for it besides updating the documentation on it's concern.

It seems like BUILDING.txt is missing some information about native compression libraries. Noticeably if you are missing zlib/bzip2/snappy devel libraries, those will get silently skipped unless you pass the -Drequire.$LIB option (e.x. -Drequire.snappy). [Ref. JIRA issue.]

The correction should be release with Hadoop 2.8.0


Is there any way to be notified about system events in Ubuntu?

when the date changes -- use cron (man at); also how to execute a command after resume from suspend?

Another thing is for app to be notified. Usual thing for IPC is signal handler (POSIX setsig()) and using kill command with custom signal id, e.g. SIGUSR1. Do you write with C?


Through process of elimination I found some applets can cause this behavior, in my case these two:

temperature@fevimu (for CPU temp on each core/cumulative)
gputemperature@silentage.com (ATI and NVidia cards)

Of the two, the GPU applet appears more impacting. Running the CPU applet for several hours results in occasional window freezes concurrent with CPU spikes.

ALT+F2 - r usually restores Cinnamon to typical CPU (2%-3%) and reduces its RAM utilization by 50MB-75MB upon restart. Seems to indicate some applets which do a lot of frequent polling are not cleaning up after themselves.

About my laptop -

System report generating...

SYS

Linux fender 4.2.0-1-amd64 #1 SMP Debian 4.2.6-1 (2015-11-10) x86_64 GNU/Linux

CPU

model name  : Intel(R) Core(TM)2 Duo CPU     T9600  @ 2.80GHz
model name  : Intel(R) Core(TM)2 Duo CPU     T9600  @ 2.80GHz

RAM

KiB Mem :  8108740 total,   330984 free,  2361056 used,  5416700 buff/cache

HDD

/dev/sda1       38317204  17780024  18567696  49% /
/dev/sda5       81572908  23645824  53760312  31% /home
/dev/sdb1      240232960  39382632 188624076  18% /int

GPU

01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] RV635/M86 [Mobility Radeon HD 3650]

GUI

CINNAMON_VERSION=2.6.13

UXE

2.6.13-1 cinnamon
2.6.13-1 cinnamon-common
2.6.0-2 cinnamon-control-center
2.6.0-2 cinnamon-control-center-data
2.6.2 cinnamon-core
2.6.5-1 cinnamon-desktop-data
2.6.2 cinnamon-desktop-environment
2.6.3-1 cinnamon-l10n
2.6.4-2 cinnamon-screensaver
2.6.3-2 cinnamon-session
2.6.3-2 cinnamon-session-common
2.6.3-2 cinnamon-settings-daemon
2.6.5-1 gir1.2-cinnamondesktop-3.0
2.6.0-2 libcinnamon-control-center1:amd64
2.6.5-1 libcinnamon-desktop4:amd64
2.6.0-2 libcinnamon-menu-3-0


How to download Ubuntu Server backups automatically?

Is your dekstop an Ubuntu (or other Linux) machine?

I ask because if it were, and this were me, I'd write a simple script on the desktop that mounts (using sshfs) the server into the local filesystem (although this is probably not required)) and then uses rsync to create a backup of your data. Then I'd just set a cron-job on the desktop to run the backup. I'm doing it this way around (rather than having the server push a backup) because only the desktop knows when it's turned on. It seems silly to add another layer of logic when you could just have the desktop do all the heavy lifting.

For an efficient back-up system, you do also have to be conscious of what data you need to back up. There's usually little value in cloning the entire filesystem once a day because the most likely restore procedure will be a re-imaging that restores most of the system.

Most occasions, it only makes sense to have a copy of your unique data (your websites and their databases or whatever you're running on the server), the /etc/ dir (to speed up reconfiguring the reimaged server) and a list of packages that were installed so you can do a bulk-apt-get-install.

Of course, I'm not you and I imagine my servers are configured differently to yours so what data you need is ultimately up to you.

To get you started, a simple rsync command could be:

rsync -avze ssh user@example.com:/data/ /local/backup/path/

For this to work transparently without ineraction, you'll want to set up ssh key auth which will bypass a password prompt but does raise a security issue (your dekstop user can log in without a password!).

If that's an issue, you could run a script on the server to create a backup .tar.gz and then create a new user who only has permission to get this one file. Then alter your desktop script to log in with this new backup user and grab the tar.

Or you could have the desktop script promt you for the ssh password. Not fully automated but fairly easy.