Mouse stopped responding after installing Ubuntu Server

It's next to impossible for Ubuntu Server installation to affect the functioning of the mouse in Windows 7 - no code from Ubuntu is ran when you boot into Windows 7, it's just bits on your hard drive.

Check the cable, maybe put in new batteries if it's a wireless mouse.

I would also try unplugging the mouse after Windows has loaded and plugging it back.


There is any application that can be used to monitor for much time a computer is turned on?

You can use uptimed which does exactly that. It's a daemon to record uptime records.

Install it by running following command in your terminal:

sudo apt-get install uptimed

Once installed you can use uprecords command to check your uptime records.


Remove the first window when starting from usb

You have set up a persistent file. Any apps you install, documents you store on the casper filesystem, or configuration changes you make will be kept. This is not the same as a full system, which is designed for permanent use.

To see how to install Ubuntu to your USB without it being a Live USB, see How do I install Ubuntu to a USB key? (without using Startup Disk Creator). But what you will find there is that all you have to do is basically start the Ubuntu installation process from another Live USB and select your other USB as the target for installation.

If you want to experiment with this but your USB stick is under 4.4 GB, you could give the minimal image a shot.


What are the privlages i should give to a standard user account?

after add user for setup privilage do bellow guid
first setup your favorit edittor for open sudoconfiguration file

sudo update-alternatives --config editor

after setup favorite edditor open sudo configuration with sudo visudo
find line with like this content # User privilege specification and add similar demo        ALL=(ALL:ALL) ALL
The first field indicates the username that the rule will apply to (demo).

demo     ALL=(ALL:ALL) ALL

The first "ALL" indicates that this rule applies to all hosts.

demo     ALL=(ALL:ALL) ALL

This "ALL" indicates that the demo user can run commands as all users.

demo     ALL=(ALL:ALL) ALL

This "ALL" indicates that the demo user can run commands as all groups.

demo     ALL=(ALL:ALL) ALL

The last "ALL" indicates these rules apply to all commands.

demo     ALL=(ALL:ALL) ALL

Names beginning with a "%" indicate group names.

There are a number of ways that you can achieve more control over how sudo reacts to a call.

The updatedb command associated with the "mlocate" package is relatively harmless. If we want to allow users to execute it with root privileges without having to type a password, we can make a rule like this:

GROUPONE    ALL = NOPASSWD: /usr/bin/updatedb

NOPASSWD is a "tag" that means no password will be requested. It has a companion command called PASSWD, which is the default behavior. A tag is relevant for the rest of the rule unless overruled by its "twin" tag later down the line.

For instance, we can have a line like this:

GROUPTWO    ALL = NOPASSWD: /usr/bin/updatedb, PASSWD: /bin/kill

Another helpful tag is "NOEXEC", which can be used to prevent some dangerous behavior in certain programs.

For example, some programs, like "less", can spawn other commands by typing this from within their interface:

!command_to_run
This basically executes any command the user gives it with the same permissions that "less" is running under, which can be quite dangerous.

To restrict this, we could use a line like this:

username    ALL = NOEXEC: /usr/bin/less

If you are simply wondering what kind of privileges are defined for your username, you can type:

sudo -l

source of article


Unable to successfully mount Samsung phone

Try running:

sudo apt-get install jmtpfs

Then connect your phone to computer via USB and enable transfer files on mobile.
Your phone should be detected.


The manpage suggests an environment variable:

PDSH_SSH_ARGS_APPEND="-i $HOME/.ssh/mykey.pem"

You need to either export the variable (to make it available
to pdsh's child processes) or define the variable and run
the command in one go:

# Either:
export PDSH_SSH_ARGS_APPEND="-i $HOME/.ssh/mykey.pem"
pdsh -w^server.txt date

# Or
PDSH_SSH_ARGS_APPEND="-i $HOME/.ssh/mykey.pem" pdsh -w^server.txt date

I don't know why you gave -R ssh; for me it perfectly works without.

See also "pdsh can't find identity file, but ssh can. why?" on stackoverflow.
The poster has a different problem (quoting) but uses the same approach.


I am not at all sure the bug you linked to is relevant here. You can't just chroot to an arbitrary directory like that. By default, chroot will set / to the directory you gave it and then try to run /bin/sh (or whatever the default shell is). Since there is no /bin/sh in the target directory, it complains. That's what you see in the first error:

chroot: failed to run command ‘/bin/bash’: No such file or directory

The second error is probably because you have mounted a FAT or NTFS partition in the external drive and you haven't set it up to allow execution. It looks like /path/to/external/bin/sh exists but can't be executed. Try mounting the SD card with execution enabled.

Note that the guide you linked to tells you to download an Ubuntu image and use that as the chroot target. It doesn't tell you to use your home directory for it!

To illustrate:

$ sudo chroot .
chroot: failed to run command ‘/bin/bash’: No such file or directory
$ cp /bin/busybox bin/sh
$ sudo chroot /bin/sh   ### works!
# /


what version of ubutu should I install for upgrade, this is my computers capacity

At least 12.10 for support of your (I presume) GMA500. Personally I use Kubuntu and I think you will find Unity or Gnome 3 to be very slow. If you do not like KDE, you can consider Xubuntu or Lubuntu.

NOTE: There is no 3d support available for the GMA500.


How to batch rename files (.jpg) randomly?

I suppose the following could work. Assuming the prefix of your filenames is "DSC" you can use the following command in the terminal (untested!)

cd /path/to/photos
rename 's/DSC/'$RANDOM'/' *.jpg

This uses the perl rename command to match regular expressions and replace them. In this case, we are substituting "DSC" with a random number in the filename for all .jpg files. Change the "DSC" to whatever your photos' prefix is.

another method (also untested) is with a bash script:

#!/bin/bash
for f in *.jpg; do
  mv "$f" $RANDOM-"$f"
done


How to detach process in a server with X windows?

From the question on SO:

I don't think it is possible over ssh. When you have such process, it needs to communicate with the X server (which is running on your client). You can't just take it away from the process.

If you need to run processes with X detached, you need to use X server on that remote machine. For this use case, VNC is probably better solution, since it can create virtual displays that are available even after disconnect.


Where is the "copy video dvd" function on Ubuntu 12.04 Totem 3.0.1

You can use the "Save a copy" option in the "Film" menu (I'm translating this options from Spanish version of Ubuntu).


Where can I get themes and eye-candy for my desktop?

Web Upd8 is where I got a lot of nice themes and tips for customization. Plus they maintain a PPA with modding/utility apps.They also have a PPA ppa:webupd8team/themes (How to add PPAs) specifically for themes.


This is most likely a hardware problem. Could be the fan is not working well, so it needs to run on high, or could be the heat sink to the CPU was knocked loose.

Otherwise try ps -ef to see if there are any processes running that are causing your CPU to overheat.


Logical volume is not mounted but is in use. Please close all applications using this device (eg iscsi)

Increasing the size of a logical volume that's being used is indeed possible. That's one of the major advantages of using LVM in the first place.

It's just these gui tools ... meh ... forget about 'em.

(optional) Check how much space you've got left on your Volume Group with sudo vgdisplay
Find the name of your Logical Volume with sudo lvdisplay
Extend the volume by 5GB: sudo lvextend -L+5GB /dev/ssd/sysLV
Increase the filesystem size to match the LV: sudo resize2fs /dev/ssd/sysLV (ext4 only, see this link for other filesystems)
df -h should now report the correct size. Be happy, praise the command line!


Is it possible to install Python 2.5 in 11.04?

Launchpad has a topic about this.

Here is a tutorial on installing python 2.5 on Ubuntu 10.10. 11.04 should be identical for this.

From that websites the commands would be:

sudo add-apt-repository ppa:fkrull/deadsnakes
sudo apt-get update
sudo apt-get install python2.5

Executing python2.5 file at commandline would execute 'file' with v2.5. python file would use the newest version.

I only used this once roughly a year ago so be wary of pitfalls.


Prevent temporally suspend/hibernate from script?

To prvent hibernation, create /var/run/do-not-hibernate:

sudo touch /var/run/do-not-hibernate

The file /usr/lib/pm-utils/sleep.d/000kernel-change makes this work. If you need to disable suspend, create a new file for that, say /etc/pm/sleep.d/000_prevent_suspend_hibernate:

#!/bin/sh
# Prevents the machine from suspending or hibernating when
# the file /var/run/do-not-hibernate-or-suspend exist
case "$1" in
  suspend|hibernate)
    [ -f /var/run/do-not-hibernate-or-suspend ] && exit 1
    ;;
esac

Make it executable:

sudo chmod +x /etc/pm/sleep.d/000_prevent_suspend_hibernate

In case you need to prevent the machine from suspending or hibernating, create a file:

sudo touch /var/run/do-not-hibernate-or-suspend

After rebooting or removing this file, suspending and hibernating works again.


No network connection in Ubuntu Server 16.04

It sounds like your server isn't able to get a DHCP assigned IP address. Have you checked your DHCP server?

You could also try a static IP addresss (probably best for a server anyway) see https://help.ubuntu.com/community/NetworkConfigurationCommandLine/Automatic


how to overwrite windows 7 with ubuntu on hp mini 110-3100

Try burning the Ubuntu iso on a USB flash device. Restart your computer and boot from the flash drive (you may need to access the boot menu from your BIOS (the screen when you first start up), try smashing F1-F12 upon startup). Install Ubuntu using the entire disk and your Windows 7 will be GONE!


xserver boot failed after installing new GPU

Try with this.

sudo dpkg-reconfigure xserver-xorg-video-ati
sudo dpkg-reconfigure xserver-xorg-video-radeon

and reboot.


Change user password while password is empty

Try running passwd from a terminal. It'll ask you for your old password, and then for your new one.
If it doesn't accept the old one there, run sudo passwd <username> replacing <username> with your username. That will make sure you can change it without the need for your old one, in the hope that it accepts the sudo password.


You won't find because python3-PyWavelets is python package.

Run pip install PyWavelets

If you are getting error pip not found, then

sudo apt-get install python3-pip

To install with conda

conda install pywavelets


Using preseed, how do I select the HWE kernel?

There are two options,

If the machine will boot with the earlier kernel this will work.

d-i pkgsel/include will work, and should exist in your config, appending linux-generic-hwe-16.04 will boot to the hwe kernel once the install is complete.

Or you can this line:

d-i base-installer/kernel/override-image string linux-generic-hwe-16.04

After this line:

d-i keyboard-configuration/xkb-keymap

The second option is preferable in my experience.


16.10 Cannot sign in to Ubuntu One account from Ubuntu Software

It is a known and reported bug https://bugs.launchpad.net/bugs/1616943

you can install it manually by typing

sudo snap install krita

in the terminal.


How to recover the list of the files from a broken disk

Finally use the command strings mlocate.db and I obtained the complete list of files and folders of the system. After that I copy the part that i need and order manually.


How do I open IDLE 3.4 when 2.7 is already installed?

Type sudo apt-get install idle3 to install Idle 3.

Afterwards it can be started with the command idle3.


Ubuntu 16.04: no module named 'lsb_release' error while creating startup disk

For 15.10 or 15.04, I would recommend using Gnome Disk Utility (aka 'disks').

Simply, click on 'cog' icon (top right) and select 'Restore Disk Image' to copy the ISO file to a 2GB (or 4GB) USB stick.

Note: Make sure you select the correct target media, and don't override something important.

--

For Windows 7 Pro/Windows 10, use 'Rufus' utility [https://rufus.akeo.ie/]

Select the ISO file, choose GPT partition, etc.


The problem are your line ending characters. Your file was created or edited on a Windows system and uses Windows/DOS-style line endings (CR+LF), whereas Linux systems like Ubuntu require Unix-style line endings (LF).

There is a simple tool that can convert the two different styles for you called dos2unix.

Install it by running

sudo apt install dos2unix

After that, you can convert files in either direction using one of the commands

dos2unix /PATH/TO/YOUR/WINDOWS_FILE
unix2dos /PATH/TO/YOUR/LINUX_FILE

Example:

$ cat test.py
#!/usr/bin/env python3
print("ok")

$ ./test.py
/usr/bin/env: ‘python3\r’: No such file or directory
$ dos2unix test.py
dos2unix: converting file test.py to Unix format ...
$ ./test.py
ok

To also come back to what you tried first, the shebang line

#!/usr/bin python3

is of course wrong. It tries to execute the file /usr/bin with python3 and the filename of your script as arguments. This must obviously fail because /usr/bin is a directory and no executable file.


When trying to install VirtualBox I am asked for a CD which I do not have

Your version of Ubuntu was originally installed from that CD/DVD. If you still have it, put in in the drive.

Alternatively, you will need to edit the file /etc/apt/sources.list and comment out (add a '#' character at the start) the line starting deb cdrom:....

I do this using a terminal session. There may be a GUI to do this but I've never looked for one.


two monitors and unity workspaces settings

Try gnome-tweaks, Workspaces/Display handling and set 'Workspaces on primary display only'.


Snippy seems to work for me quite nicely. No GUI, but quite functional. Glad I finally found a replacement.

http://leon.vankammen.eu/tech/snippy-autocompletion-for-console-and-browser-window-manager-using-bash.html

The link also mentions another choice in the comments.

Snippy itself is available via a tinyurl and installation is as follows:

curl -L "http://tinyurl.com/o9d6ch5" > snippy.sh
chmod 755 snippy.sh
./snippy.sh

Alternatively, there appears to be an enhanced version located here in github

Installation works the same.


Graphics problems on Asus EEE 1101 HA, Precise Pangolin

I found probably the best solution to fix graphic error: add "service lightdm restart" line to rc.local.

gksudo gedit /etc/rc.local

Add to new line after coments and before "exit 0":

  service lightdm restart


Fresh Ubuntu 18.04 installation has no dpkg and no internet

The answer proposed by chili555 worked perfectly. I don't know why the installation doesn't do this automatically but at least we have chili to the rescue!


Desktop environment agnostic method for prompting the user for a password?

The manpage for the zenity command  contains the following description:

  zenity  is a program that will display GTK+ dialogs, and return (either in the return code, or on standard output) the users input.

As far as I can tell (and my testing backs this up), this will work in both the Gnome and KDE desktop environments. For example:

zenity --password | sudo -S nautilus

...will prompt you for your root password and then launch Nautilus.


Ubuntu installation 16.04.2 LTS Display Not Working

Thanks to Organic Marble!

I inserted nomodeset in GRUB and it worked !


Network adapter suddenly stopped working under Ubuntu 12.10

I have found a solution to my own question in a blog. The problem is not intuitive at all. It looks like that the nework adapter’s EEPROM is damaged, creating a checksum error for the NVM (The NVM Checksum Is Not Valid) that breaks the Ubuntu driver loading  therefore the eth0 alias is not created and there isn’t a manageable ethernet adapter for the Ubuntu network manger. Windows doesn't perform this check so that's why it works ok there.

Running dmesg | grep e1000 should show a line stating "The NVM Checksum Is Not Valid"

The solution: remove the old driver, install the updated network controller driver, create a MS DOS boot pen drive, reboot, flash the card eeprom, and reboot again.

All these steps are explained in detail in an excellent tutorial by Sorcerer found in http://thesorcerer.wordpress.com/2011/07/01/guide-intel-82573l-gigabit-ethernet-with-ubuntu-11-04-and-fix-pxe-e05/

It appears that many Intel LAN adapters suffer from this same issue: 82563, 82566, 82567, 82571, 82572, 82573, 82574, 82577, 82578, 82579, or 82583 -based.

Cheers!


Read this question on stackoverflow.com and this answer by user grawity on superuser.com

You should not use $HOME in init.d, because it is not clear which users home to use, until this user logs in.

Quote from POSIX specification:

HOME
The system shall initialize this variable at the time of login to be a pathname
of the user's home directory. See <pwd.h>.

You can use little hack, to get home folder of user myuser in your script

su - myuser -c /usr/bin/env | grep HOME

It is better  to use script below, because usually there can be other HOME_* folders. Such as JAVA_HOME etc.

su - myuser -c /usr/bin/env | grep "^HOME="


How delete files - based on date in filename

This should work (if you set the correct full or relative path it is currently on the directory test)

#! /bin/bash

nowday=$(date +"%d")
nowmonth=$(date +"%m")
nowyear=$(date +"%y")

#number of days since 1 Jan 1970 (today)
nowdays=$(($(date --date="20$nowyear-$nowmonth-$nowday" +"%s")/86400))

backup_dir="test/*"
#echo $backup_dir
for file in $backup_dir
do
  hour=${file: -6: -4}
  day=${file: -9: -7}
  month=${file: -12: -10}
  year=${file: -15: -13}
  #number of days since 1 Jan 1970 (file)
  days=$(($(date --date="20$year-$month-$day" +"%s")/86400))
  if ((days < nowdays-365)); then
    # more than one year
    if ((10#$day == 1))&&((10#$hour == 0)); then
      #day is 1 hour is 0 (we keep) use this space if you want to copy or something!
      :
    else
      #Wrong day or hour
      rm $file
    fi
  else if ((days < nowdays-31)); then
    # more than one month (31 days)
    if (((10#$day == 1))||((10#$day == 8))||((10#$day == 15))||((10#$day == 22))||((10#$day == 29)))&&((10#$hour == 0)); then
      #day is 1,8,15,22,29 hour is 0 (we keep) use this space if you want to copy or something!
      :
    else
      #Wrong day or hour
      rm $file
    fi
  else if ((days < nowdays-7)); then
    # more than one week
    if ((10#$hour == 0)); then
      #hour is zero se this space if you want to copy or something!
      :
    else
      #Wrong hour
      rm $file
    fi
  else
    # less than one week (we keep) use this space if you want to copy or something!
    :
  fi fi fi

done

I have defined a month as 31 days always for checking if over 1 month. For once a week I pick days 1 8 15 22 and 29, so there is always the first day of the month. This also works on the back catalogue because it checks for midnight for each file.

The : lines are just place holders in case you want to put code there.

Give it a check before running it on everything, just in case there is an error!


Xterm also read .bashrc when starting. Add this line to your ~/.bashrc:

PS1=~$\

And restart xterm.


How to install Docker Ubuntu 18.04 with https proxy error

From docker's site here are the steps to install docker:

Update apt package index

sudo apt-get update

Install the requirements for docker

sudo apt-get install \
    apt-transport-https \
    ca-certificates \
    curl \
    gnupg-agent \
    software-properties-common

Add Docker's GPG key

curl -fsSL https://download.docker.com/linux/ubuntu/gpg | sudo apt-key add -

Note: You should check the key if it's correct. (Follow the link)

Add Docker's repository

sudo add-apt-repository \
   "deb [arch=amd64] https://download.docker.com/linux/ubuntu \
   $(lsb_release -cs) \
   stable"

Then update with apt

sudo apt-get update

And now you can install docker with apt

sudo apt-get install docker-ce docker-ce-cli containerd.io


Does removing snap from Ubuntu 20.04 server pose any problem?

Ubuntu is designed to use snap packages as the delivery platform for software.
Apparently, on the Google Cloud Platform, Ubuntu has been configured to automatically install the google-cloud-sdk for you, and by effect to keep it up to date. It makes sense to use these facilities since they have been designed to help you and you get support for them.
If you really want to remove snapd and the snap packages, you can obviously do so as well. However, you would need to be able to install and maintain manually the google-cloud-sdk and other default packages.


How do I get Rythymbox Music Player to omit the Oracle Java JDK binary from the playlists?

Right click on a music file such as a .mp3. Select Properties and in the Open With tab change the default music player to Movie Player. Now when you double-click a similar file, it will not invoke Rythymbox and not have to assemble the Rythymbox playlist.


Brightness settings not working, stuck on Zero brightness

sudo software-properties-gtk

Click on the Additional Drivers tab in the Software Sources menu

Install your device drivers


Is it possible to make ubuntu switch workspaces on a timed interval?

Yes, and it is very easy. You just need a tool to press the keys you would press to change the workspace. One of such tools is xdotool. To install it:

 $ sudo apt-get install xdotool

Then you just need to create a script like this one (here I assume you only have 2 workspaces, and you use Ctrl+Alt+Left/Right to change between them, but you can easily extend it to match your needs):

!/bin/bash

TIME=10 # shifts workspace after 10 sec.

while [ 1 ]; do
        sleep $TIME
        xdotool key ctrl+alt+Right
        sleep $TIME
        xdotool key ctrl+alt+Left
done

Don't forget to make it executable. If you create it in /usr/local/bin/workspace_switcher you can do that using

 $ sudo chmod +x /usr/local/bin/workspace_switcher

Then to start it you just have to press Alt+F2 and type workspace_switcher. To stop it, you can use killall workspace_switcher


Can't boot Windows without connecting external device that has Ubuntu installed on it

It sounds like  GRUB is installed on USB B - so your system will only boot, even into Windows, when USB B is connected. When USB B is disconnected the boot loader can't find GRUB and fails.

You can run boot repair and make sure that GRUB is installed on your internal hard disk - e.g. sda

https://help.ubuntu.com/community/Boot-Repair


Media play/pause & track prev/next stopped working after reboot

Do the following:

gsettings set org.gnome.settings-daemon.plugins.media-keys previous ''
gsettings set org.gnome.settings-daemon.plugins.media-keys next ''
gsettings set org.gnome.settings-daemon.plugins.media-keys volume-mute ''

and then try again as the keys won't be trapped any more so Gnome can do whatever it wants with them.

If one of the keys stops working, rebind it in Keyboard settings.


I am the developer of the Linux OneDrive Client:

https://github.com/abraunegg/onedrive

For Ubuntu platforms, either use the Ubuntu PPA or build from source.
Any issues, or questions, post a query on GitHub


Cannot ping in new Ubuntu Server install

You shouldn't have messed with the pre-existing lo (loopback) interface: you need to revert that to

# interfaces(5) file used by ifup(8) and ifdown(8)
auto lo
iface lo inet loopback

and then add your external static interface, for example

auto em1
iface em1 inet static
address 192.168.1.120
netmask 255.255.255.0
network 192.168.1.0
gateway 192.168.1.1

(these are not necessarily correct for your network: you will need to verify).
You will also likely need to add at least one DNS nameserver e.g. to use Google's public DNS servers

dns-nameservers 8.8.8.8  8.8.4.4

Alternatively, if your router supports DHCP address reservation you might want to use that instead - it's arguably simpler, especially for home networks.


How to install libxcb-randr 1.12 on Ubuntu 16.04?

Uninstall libxcb-randr0.

sudo apt remove libxcb-randr0

Manually download libxcb-randr0 (1.12-1ubuntu1) from the official Ubuntu 17.10 repositories from here.

Under the Download libxcb-randr0 section click either the red amd64 link or the i386 link, depending on your OS's architecture.
Select a nearby mirror and download libxcb-randr0.

Open the terminal, and change directories using cd to the directory containing the libxcb-randr0_1.12-1ubuntu1_amd64.deb file that you downloaded.
Install libxcb-randr0_1.12-1ubuntu1_amd64.deb with this command:

sudo dpkg -i libxcb-randr0_1.12-1ubuntu1_amd64.deb # the i386 .deb file has a different name

Run sudo apt-mark hold libxcb-randr0 which will prevent libxcb-randr0 from being automatically installed, upgraded or removed.


Restrict user from changing to a directory outside of /home/username

Now, when I change my user to username via su - username, I am still able to view files and folders outside of my /home/username directory. Also note that root owns /home/username.

Restrictions on SSH aren't going to affect su. The settings seem fine to me, so you should test it by doing ssh username@localhost and sftp username@localhost. Since you have said that the user logs in via SSH, given these settings, su shouldn't be a problem.


Bootable USB stick created for installation doesn't work

You should try unetbootin to make a bootable usb. It's nice and simple

Or from a terminal:

sudo apt-get install unetbootin

also available for windows


Combining the comment from @steeldriver and this thread.

  You need to use recovery mode from Ubuntu.

  First, you have to hold shift when booting. You will be seeing this menu. Then select a menu with (recovery mode) in it. Preferred the 2nd from top.

  Then, you should see this menu. Choose root.

  After that, you'll see a root prompt, something like this :

root@ubuntu:~#

  You see, using recovery will get you in read-only state. You need to make your system read write with this command.

mount -o rw,remount /

  Then, you can readd your user to sudo with this command.

adduser YOUR_USERNAME sudo

  Reboot as usual and you'll be able to use sudo.


Difficulties installing AMD 8550g drivers

Thought it would help to tell you that support for the 8550G, as far as I could tell, didn't start until Catalyst 13.10 so you'll need either 13.10 or 13.11. I've found them to be a real pain, using Linux Mint Mate 15, but it might be better for you. Installed via the .run from AMD's site.


Is there a way to sync music on my iphone?

I do not know much about Iphones, but on my Android I use Dropbox to sync music and documents between my phone and computer automatically
I would be surprised if dropbox is not available for apple


Please check permissions of the file /home/john/.ssh/id_rsa as the connection is established but the file is not found. In my last case it was a permission mistake.
The .ssh directory permissions should be 700 (drwx------).  The public key (.pub file) should be 644 (-rw-r--r--). The private key (id_rsa) on the client host, and the authorized_keys file on the server, should be 600 (-rw-------).


Ubuntu 16.04 flickering and disappearing screen

You have to install the Nvidia driver.

You can install it from the Addition Drivers application. (Dash > Additional Drivers.)

Choose the one marked as "tested".


How can I delete a write only protected folder

From the terminal you can run:

sudo rm -r /my/locked/directory

as the instruction will prompt any warning message during the execution and you will be able to check what are you deleting. Otherwise, if you have checked the warning and are completely sure of files and subfolders contained, you can run:

sudo rm -rf /my/locked/directory

This will remove recursively (-r) your folder, subfolders and any contents without prompt any warning (-f) .

If you receive the message: rm: cannot remove '/my/locked/directory': operation not permitted, then make sure directory (or file) is not protected using extended file system i attribute.

A file/folder with the i attribute cannot be modified, it cannot be deleted or renamed, no link can be created to this file and no data can be written to the file. Only root can add or remove i attribute.

Use lsattr command to verify that file/folder is not write protected using extended i attribute - output should be:

----i-------- /my/locked/directory

To remove the i attribute you can run:

sudo chattr -i /my/locked/directory

then check again with lsattr. The i should have been removed. If removed run the sudo rm -r instructions above.


Install meter stops when installing apps in Ubuntu Software Center

Sometimes, there is a dialog box that opens behind the software center window that prevents installation from proceeding. When a selection is made, installation proceeds.

This isn't always the case, I've always been frustrated with how slow software center is.

Next, the synaptic package manager isn't quite as nice but it gets the job done and it's really fast. Run the following commands to install:

sudo apt-get update
sudo apt-get install synaptic

Now, search your apps for synaptic package manager.

Search for and select packages. Then, click apply and always review the list before accepting the changes.

help.ubuntu.com/community/SynapticHowto

Also, it isn't typically good practice to install packages using deb files unless the package is not available through apt-get.

You can search for packages using apt-get as well. Here's an example:

apt-cache search synaptic

To narrow the results, you can use grep to list results containing a keyword like in this example:

apt-cache search synaptic | grep "package manager"

Finally, install a package using the following command (this example installs synaptic):

sudo apt-get install synaptic

To update your list of packages:

sudo apt-get update

and to update all your packages:

sudo apt-get upgrade


tee is not necessary in that command.

You just need to edit the file /sys/class/backlight/intel_backlight/brightness to add 937, as the file is only writeable by the owner, root (user with UID 0), any manner that can do exactly that would suffice.

You could just do:

sudo bash -c 'echo "937" >/sys/class/backlight/intel_backlight/brightness'

In that command, tee is being run with sudo i.e. being run as root as the file /sys/class/backlight/intel_backlight/brightness in only writable by root.

Even you can start an interactive-login session of your SHELL for root by:

sudo -i

and open-write-close the file with any command or your editor of choice (and later exit that session), but that would be clumsy and unnecessary as you want to run just a single command.

Also you don't need the sudo with echo, do:

echo "937" | sudo tee /sys/class/backlight/intel_backlight/brightness


I suggest using privoxy as a... well, another proxy! between apt and your actual proxy.

Then in /etc/apt/apt.conf you can pass all traffic to privoxy:

Acquire::http::Proxy "http://localhost:8118";
Acquire::https::Proxy "http://localhost:8118";

And then in privoxy config /etc/privoxy/config decide how to manage and forward the traffics.

Like:

forward   192.168.1.*                .
forward   us.archive.ubuntu.com      .
forward    *.ubuntu.com              http://127.0.0.1:8080
forward   security.ubuntu.com        http://127.0.0.1:8080

In this example us and 192.168.1.* will go directly, *.ubuntu and security will go through your proxy.


DBAN has a number of erase options. A lot depends on whether you are concerned whether any of the original data would be recoverable. I'll consider this unlikely as it's not your data and since it was still on the system when you purchased it I would think it unlikely that the seller was concerned about it either. The installation process offers to erase the drive and install Ubuntu as noted by mikewhatever in his comment This should be sufficient in your case. However if you feel the need to perform a secure erase on the drive this can be managed via the live media Ubuntu installer via the Try Ubuntu option and one of the numerous methods described here. My personal preference is dd (nicknamed disk destroyer due to it's unforgiving nature when people choose the wrong device to wipe.) Another good choice is to use the built-in secure erase feature of the drive itself.


Ubuntu 18.04 login loop after installing flatpak

I had the same problem. In my case the problem was that the flatpak directory in the /home/test/.local/share directory was owned by root:root. I fixed this as follows:

Press Ctrl+Alt+F3.
Then log in.
Fix directory owner.

sudo chown -R test:test /home/test/.local/share/flatpak

You can go back to the GUI by pressing Ctrl+Alt+F2.
Login works.


cronjob cannot find environment variables defined in .bashrc

Write a small bash script mypythonscript consisting of:

#!/bin/bash
set ENVIRONMENT_VARIABLE_1=...
set ENVIRONMENT_VARIABLE_2=...
/usr/bin/python /srv/x/y/src/run.py > /tmp/listener.log 2>&1

Make it executable:

chmod +x mypythonscript

In the crontab replace the line by

* * * * * /path/to/mypythonscript


How to managing ECDSA key fingerprints on mobile host

Use SSH certificates (aka ssh keys signed using ssh keys). It is well described in the manual page for sshd.

With certificates, you will be able to verify authenticity of the host regardless its IP.


Postman.desktop not showing up in GNOME Dash in Ubuntu 17.10

I see you're following the gnome desktop file instructions. Try following the Postman Installation documentation here

When I tried installing Postman, the icon only showed up in my gnome application menu after I ran sudo ln -s /opt/Postman/Postman /usr/bin/postman from the instructions.

EDIT: Starting with version 6.1.3, run sudo ln -s /opt/Postman/app/Postman /usr/bin/postman instead.


- to: 172.17.1.0/24
    via: 172.17.1.1
    metric: 101

This is incorrect.  172.17.1.0/24 is your local network, and you are trying to route all traffic for it via 172.17.1.1.  That machine is probably not configured to route traffic both to and from 172.17.1..0 on the same interface.  If you drop this route, traffic to 172.17.1.155 will be routed via your local network instead, which should work.


Removing of packages is done by a package name, not by file name.

You can remove it by

 sudo dpkg --purge youtube-dl

This command will also remove configuration files of that package.

Just to remove the package and leave configs, run

sudo dpkg -r youtube-dl

If you deleted some files of the package manually, you can get an error messaage

package is in a very bad inconsistent state; you should reinstall it before attempting a removal Errors were encountered while processing: youtube-dl

In this case re-install it again and then remove

 sudo dpkg -i youtube-dl_2015.06.04.1-1~webupd8~trusty0_all.deb
 sudo dpkg -r youtube-dl

And in the future never delete any files installed by deb packages!

This can break the whole system


To hold a package:

In short: sudo apt-mark hold <package>

or

echo <package> hold | sudo dpkg --set-selections

To unhold a package:

In short: sudo apt-mark unhold <package>

or

echo <package> install | sudo dpkg --set-selections


As of Ubuntu Trusy 14.04, lightdm-set-defaults is no longer available.  This is because lightdm now uses a configuration directory /etc/lightdm/lightdm.conf.d/ rather than a single configuration file.  The files in this directory can be edited by hand, new files can be added, or files can be removed.  There is no longer any need for a command that edits the single configuration file.


How do I set the grub timeout and the grub default boot entry?

Press Alt + F2, type gksudo gedit /etc/default/grub press Enter and enter your password.
You will see the following contents:

GRUB_DEFAULT=0
GRUB_HIDDEN_TIMEOUT=0
GRUB_HIDDEN_TIMEOUT_QUIET=true
GRUB_TIMEOUT=10
GRUB_DISTRIBUTOR=`lsb_release -i -s 2> /dev/null || echo Debian`
GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"
GRUB_CMDLINE_LINUX=""

You can change the default from 0 to any number, corresponding to the entry in the Grub bootup menu (first entry is 0, second is 1, etc.)
You can change the "hidden timeout" (no menu); and also display the countdown (GRUB_HIDDEN_TIMEOUT_QUIET=false)
You can force the grub menu to show by commenting out the two GRUB_HIDDEN lines with a # at the beginning of the line
And set the grub menu timeout (default is 10 seconds)
Make your changes, press Ctrl + S to save and Ctrl + Q to exit
Important: Open a terminal with Ctrl + Alt + T and type sudo update-grub to apply the changes you just made
Reboot and you should see your timeout/default entry change

Linked Question:

How do I set Windows to boot as the default in the boot loader?


./configure command completed with warning, configure: WARNING: `missing' script is too old or missing

The Linux Version of softwedge-1.0.0.zip archive was apparently created with DOS-style CRLF line endings.

Start over, but this time use unzip -a to convert text files to the correct line endings. From man unzip:

   -a     convert  text files.  Ordinarily all files are extracted exactly
          as they are stored (as ``binary'' files).  The -a option  causes
          files  identified by zip as text files (those with the `t' label
          in zipinfo  listings,  rather  than  `b')  to  be  automatically
          extracted  as such, converting line endings, end-of-file charac‐
          ters and the character set itself as necessary.


Dealing with old Thunderbird inbox e-mails in the terminal

Citing kb.mozillazine.org:

  Thunderbird uses mbox files to store the messages for a folder. Each mbox file is an ordinary 7-bit ASCII text file with the folders name and no file extension. You can read the messages using a text editor though it will be very user unfriendly due to all of the headers that are normally hidden, HTML tags not being interpreted, and seeing big blocks of characters all run together for any binary attachments.

If you don't mind some gibberish those files can simply be processed with grep and friends, for example:

$ grep -r --exclude="*.msf" "Subject: some subject" /path/to/Inbox.sbd
mail_dir_01:Subject: some subject
$ sed -n '/Subject: some subject/,/^From - /p' mail_dir_01

Here, grep searches all mail folders inside the Inbox for a mail with the subject “some subject” and gives you its folder file name mail_dir_01, sed then displays the mail from the Subject: line on. However, awk may provide better approaches.


Assuming you've installed the libraries right, the command you're using to compile the code through the terminal is wrong. I've tried it myself, and it doesn't work!
Try the following,

g++ canny.cpp -o canny `pkg-config --cflags --libs opencv`

This line should work fine. Please, try it and let us know.


The release notes says

  You can upgrade to Ubuntu 20.04 LTS from either Ubuntu 18.04 LTS or Ubuntu 19.10.

FWIW. The installation (not upgrade) of Xubuntu 20.04 to my Dell XPS-13 9365 completed flawlessly. To be on the save side, I've decided to keep my previous Ubuntu along with the original Windows in partitions 4,5 and install 20.04 into the partition 6.

shell> lsblk
NAME        MAJ:MIN RM   SIZE RO TYPE MOUNTPOINT
loop0         7:0    0  62.1M  1 loop /snap/gtk-common-themes/1506
loop1         7:1    0    55M  1 loop /snap/core18/1705
loop2         7:2    0 154.3M  1 loop /snap/chromium/1123
loop3         7:3    0  27.1M  1 loop /snap/snapd/7264
nvme0n1     259:0    0 238.5G  0 disk
├─nvme0n1p1 259:1    0   499M  0 part
├─nvme0n1p2 259:2    0   100M  0 part /boot/efi
├─nvme0n1p3 259:3    0    16M  0 part
├─nvme0n1p4 259:4    0  39.6G  0 part
├─nvme0n1p5 259:5    0  39.1G  0 part
├─nvme0n1p6 259:6    0  39.1G  0 part /
├─nvme0n1p7 259:7    0 104.5G  0 part /export
└─nvme0n1p8 259:8    0  15.6G  0 part [SWAP]

HW support of XPS 13 is included out of the box. All is working except the fingerprint (supported, but I haven't found any GUI in Xfce). Kernel 5.4 is great. Average core temperature dropped by 10-20 degrees! My 19.10 Xubuntu desktop was running on 60-70 C average. The core temperature is now under 40 degree C when idle and 50 degree C on 30% CPU usage (Cooler Master pad; 20 C room temperature). The graphics (Intel 615) is faster and smoother running with 3 external display on DisplayLink.


Install Gnome without extras and Ubuntu-Session

I have had the best results using:

sudo apt install gnome-session --no-install-recommends

Then just installing anything else I need once I'm in Gnome.


Why does sudo ask for a password in window after I've just authenticated in a different one?

The grace period is controlled by what sudo calls a 'ticket'. When you authenticate with sudo, it creates this ticket with a certain timestamp that basically says when the authentication should expire.

By default (this is set when the package is compiled), this timeout is, as you've found, per tty. This is a feature of sudo called 'tty_tickets'. Basically this means that, instead of creating one lock per user, sudo creates one lock per tty instead.

In order to revert back to the old behaviour and override the default, you need to edit /etc/sudoers. Find the "Defaults" line, which you already edited to change the timeout, and append ,!tty_tickets to it. This will turn off the tty_tickets feature and give you the behaviour you want.


How to add a new additional dash and launcher in Unity. (beside of current launcher)

You can enable the gnome panels by pressing Alt+F2 and type: gnome-panels

With the gnome panels enabled you still have the launcher panel on the left and the rest of the Unity “looks” but you can also add shortuts and launchers to the top and bottom panel.. just like we can on Ubuntu 10.10

To start the gnome panels without having to enter the command you can create a launcher on your desktop click with your right mouse button on your desktop and select Create Launcher. First enter a name for the launcher and type: gnome-panel in the Command field (You can add a comment if you want). When done cllick on the OK button and the launcher will be shown on your desktop.

Or you can add the command line to the startup list press Alt+F2 and type:

gnome-session-properties

Your Startup Applications Preferences manager will open now click on the Add button, enter a name and type: gnome-panel in the Command field. Add a comment if you want and click on the OK button. Now the gnome panel will enabled automatically at startup. When using this option the top gnome panel will NOT be shown because the Unity top panel overlaps it.


In a manner of speaking, yes.

sudo nvidia-settings

Then, in the left column, look for an entry called PowerMizer, and set mode Adaptive instead of Maximum Performance.

Otherwise/Also, find a way to cool your laptop (ie using a laptop cooler).


since you are using non-default port for zookeper , makesure you have same in zookeeper configuration file , zoo.cfg
as
    clientPort=2222

also make sure your hbase-env.sh file has below line.

export HBASE_MANAGES_ZK=true

also for ubuntu make sure your /etc/hosts file doesnt have loopback issue.
it should have a line similar to below.

127.0.0.1 localhost


It depends on what you are trying to achive.

In case it's just for you, you can try and backport 1.7.2 for youself. There are many tutorial about how to backport a package in Ubuntu or Debian. But if you did never package .DEB packages yourself, your milage may vary.
You can (and possibly should) request an official backport using the relevant process in Ubuntu. See https://wiki.ubuntu.com/UbuntuBackports in parallel. If you succeed with that, you will be able to replace your home grown backport with a backport that is available for everybody from the official repos later on.
In case you are developing software which is supposed to get shipped and run on arbitrary machines that run 18.04, you better stick to the versions available as otherwise you will make it very complicated for users of your software to install it.


How can I unmount a truecrypt partition which has open files on it?

There is an old thread on how to do this on the ubuntu forums here.

However I would definitely not recommend it. Even if matlab has finished with the data in the files it is still quite possible it would mess up your simulations. More importantly it is likely that it will cause an inconsistency within the file system and you would end up losing data. There is a reason it doesn't just unmount for you when files are in use. Forcing it to forego these security precautions usually ends up with bad results.


Creating a Windows 10 boot drive on ubuntu (missing media driver)

I used mkusb to create a working usb image. I used the same download I got from microsofts website so I must have been wrong about the download being incomplete.


Using Ubuntu 13.10 aside Windows 8 fast boot

No you can't and neither you should.

The fastboot feature is called as hybrid shutdown. It can be seen as partial hibernation and partial shut down. In simple words, It takes a snapshot of current memory and stores to disk to be used on next start up. A good explanation can be found here - http://www.techrepublic.com/blog/windows-and-office/how-windows-8-hybrid-shutdown-fast-boot-feature-works/

So if it is allowed to make changes to the ntfs file system by any means, on next start up win 8 won't able to know what changes were made. Because it restores from a snapshot which was made earlier. Thus leading to data corruption. To prevent this ntfs 3g driver developers made modifications that causes NTFS partitions be mountable as read-only if the driver detects a Windows system with active Fast Startup.


How to set a socks proxy server only for one user?

A few points:

Environment variables are case-sensitive. Environment variables like this tend to be uppercase.
If you're testing in bash, note the top of the ~/.profile file:

# ~/.profile: executed by the command interpreter for login shells.
# This file is not read by bash(1), if ~/.bash_profile or ~/.bash_login
# exists.
# see /usr/share/doc/bash/examples/startup-files for examples.
# the files are located in the bash-doc package.

The help wiki recommends using ~/.pam_environment instead of other files for session environment variables.
Its syntax is different than what you're expecting. See: http://linux.die.net/man/5/pam_env.conf
So (assuming ~/.pam_environment) you're probably looking for:

SOCKS_PROXY DEFAULT=socks://address:port

Otherwise this is probably just a case issue.

You mention that you're using a browser and in there may lie the actual issue. Firefox, ignores environment variables by default. There is a plugin that will look for environment variables though (it's quite old):

https://addons.mozilla.org/en-US/firefox/addon/environment-proxy/

I'm not sure how other browsers handle these things but I wouldn't be surprised if they do also ignore them.


Digital microphone needed for T60p, running Ubuntu 16.04

All generic USB audio devices are supported. Some non-standard devices may only work with proprietary drivers and software in the OSes supported by the manufacturer.


How do I get a Texas Instruments ACX 111 wireless card working?

I found this driver

http://www.bijteam.com/drivers-texas-instruments-acx-111-802-11g-wireless-network-adapter/

It works

And I followed this guide

https://help.ubuntu.com/community/WifiDocs/Driver/Ndiswrapper


You need to check the specifications as to what resolution is supported by the KVM Switch. Also, there is noticeable video quality difference in digital and analog signals especially when you use large LCDs.


I am using a 64 bit machine with Ubuntu 14.04 and I was facing the same issue myself. I tried everything under the sun including doing apt-get purge followed by apt-get install. Then tried installing from the .deb file using gdebi. But every time I was getting the same error: Ubuntu 4.2 was being loaded !

My fix was pretty simple at the end of the day. I deleted the .Skype directory present in my home directory and it solved the issue.

cd ~ && rm -r .Skype

Reference  : How to install Skype 4.3?


cat /dev/lirc0 returns rubbish if I press buttons on my remote controls

The "rubbish" is probably mode2 space and pulse data, as described here:
http://lirc.org/html/lirc.html

You can verify that the data is space and pulse data by running the following command and then pressing buttons on your remote:
mode2 -d /dev/lirc0

To teach LIRC to understand a new remote control, try the following:
irrecord -d /dev/lirc0 ~/lircd.conf

To see a list of key names, run:
irrecord --list-namespace

I tried to learn a new remote with irrecord as described above, and it did not work for me.  But I believe the above is the standard procedure.  I am running Ubuntu 16.04 on a NUC6CAY.

More info at these pages:
http://lirc.org/
https://learn.adafruit.com/using-an-ir-remote-with-a-raspberry-pi-media-center/lirc
https://learn.adafruit.com/using-an-ir-remote-with-a-raspberry-pi-media-center/using-other-remotes


Why is my Ubuntu root folder filling up?

This is usually because /var is not on its own partition.  Most logs get written there and if / is too small then just normal system activity will fill up the root filesystem with logs.
However, you can find out where the space has been used by running something like:
du -sh /*

If /var, you can put it in its own partition, figure out which logs are balooning and fix the cause(s), or just get aggressive about rotating your logs frequently.


I'd skip lastlog completely and look at the who command. This does practically everything you're asking:

$ who
oli      tty7         2013-09-20 14:33 (:0)
oli      pts/0        2013-09-20 14:33 (:0)
oli      pts/2        2013-09-21 22:00 (:0)
oli      pts/4        2013-09-25 20:09 (:0)
oli      pts/5        2013-09-24 11:02 (:0)

w is pretty good too but the login time is a bit more colloquial so not as well suited for scripting:

$ w
 20:13:15 up 5 days,  5:39,  5 users,  load average: 0.49, 0.53, 0.45
USER     TTY      FROM             LOGIN@   IDLE   JCPU   PCPU WHAT
oli      tty7     :0               Fri14    5days  8:35m  0.03s /bin/sh /usr/bin/startkde
oli      pts/0    :0               Fri14    5days  0.00s  3:36  kdeinit4: kded4 [kdeinit]
oli      pts/2    :0               Sat22    3days  0.08s  0.08s /bin/bash
oli      pts/4    :0               20:09    3.00s  0.08s  0.00s w
oli      pts/5    :0               Tue11    5:45m  2:42   2:42  node /usr/bin/grunt watch


In ubuntu 14.04, why does my internet connection keep disconnecting?

Install the driver by running in terminal:

sudo add-apt-repository ppa:hanipouspilot/rtlwifi
sudo apt-get update
sudo apt-get install rtl8192cu-dkms linux-firmware

Then reboot.


Ubuntu 14 low screen resolution on intel HD display

Have you tried installing the graphics drivers from intel ? They should work on your HD2500 GPU.

To install: open your terminal and perform these commands

Install the certificates:

wget --no-check-certificate https://download.01.org/gfx/RPM-GPG-KEY-ilg -O - | \
sudo apt-key add -
wget --no-check-certificate https://download.01.org/gfx/RPM-GPG-KEY-ilg-2 -O - | \
sudo apt-key add -

Install the intel-linux-graphics-installer (note that this is an example for the 64 bit driver. If you need another architecture please refer to the documentation link at the bottom of this post)

wget https://download.01.org/gfx/ubuntu/14.04/main/pool/main/i/intel-linux-graphics-installer/intel-linux-graphics-installer_1.0.7-0intel1_amd64.deb
sudo dpkg -i intel-linux-graphics-installer_1.0.7-0intel1_amd64.deb

Update your system

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

Install the drivers through the installation tool:

sudo intel-linux-graphics-installer

Reboot

See also the documentation:
https://01.org/linuxgraphics/downloads/2014/intelr-graphics-installer-linux-1.0.7


USB 3.0 hard drives don't spin down when "safely removed" from Nautilus

AFAIK, "Remove safely" just unmounts the device, and removes it from udev. It doesn't send any command to the drive to shut down.

On the contrary, udisks --detatch does so: (udisks manpage)

--detach device_file [--detach-options options]
       Detaches (e.g. powering down the physical port the device is
       connected to) the device represented by device_file using a
       comma-separated list of options.


Larger thumbnails in Image Viewer (eog) or gThumb

1. gThumb

Resizing thumbnails in gThumb is only possible in Browser view, as you mentioned in your post.

2. eog

I didn't found any hidden property to resize the thumbnail size in eog, too.

So I downloaded the code (eyes of gnome), and found out how to resize the thumbnails. (I think in gThumb it will be similar.)

First you have to download the source code. I suggest to use Ubuntu sources apt-get source eog, but of course you are free to use github.
Don't forget to install library dependencies with apt-get build-dep eog .

Change into the ./src directory and open the eog-list-store.h file with an editor of your choice. Search for the following line:

#define EOG_LIST_STORE_THUMB_SIZE 90

The number 90 is the pixle size of the thumbnails. Change the value to the size you need, and configure and build eog. You can test the fresh compiled program with ./build/src/eog.

A demonstration that it works is shown below; the left one has a thumbnail-width of 50, while the right one has a width of 150.

eog is programmed to be a light-weight and fast image viewer. I like the design and simplicity. If you think that resizing of thumbnails should be a feature for all, you are welcome to place your ideas on this link.

3. digiKam

digiKam is a professional photo management with the power of Open Source.
It's easy to resize thumbnails and includes a database (sqlight, sql, ...). It is really fantastic! You can order your pictures, search, make tags, ... by ease.
You can install it with

sudo apt install digikam*

or download the newest AppImages on the digiKam webpage. Make it an executable and run it!

4. xnview

As an alternative to your problem, I suggest you to use xnviewmp. You can install it via snap

sudo snap install xnviewmp

or simply download the app-image at this download-link. Change the permission to executable and run it.

Below are window screenshots of xnviewmp with two different sizes of thumbnails.

Note: XnView MP is provided as FREEWARE (NO Adware, NO Spyware) for private or educational use (including non-profit organizations).


Brightness setting not remembered after boot -- rc.local "fix" not working

You need to set the script rc.local to start automatically at start up. If that doesn't work go to /sys/class/backlight/ and run the "echo 0" to the "brightness scripts" in the folders there and if your brightness changes instantly then you know where the brightness config is and just note its location so that you can modify your rc.local again.


Ubuntu won't boot at start up I have to go into BIOS

I think there will not be any bootloader installed in your hdd. Usually bootloader will be installed on the mbr partition of the disk. If you want to boot from hdd ,use some tool to make your operating system bootable on hdd.In ubuntu you can use command line tool dd or graphical tool startup disk creator for making it. Hope it helps..


How do I recover from Firefox safe mode overwritting my preferences?

There was a folder "Old Fireforx Data" on my desktop that I missed when I asked the question. I moved the folder inside it (called "hb0i6k54.default") into ~/.mozilla/firefox and edited profiles.ini in that folder so that it would point to hb0i6k54.default - and that fixed the problem.


you can download ubuntuone from software center
           or
type in terminal

sudo add-apt-repository ppa:apachelogger/ubuntuone-kde

sudo apt-get update

sudo apt-get install ubuntuone-kde

and

you can download any other file manager rather than dolphin

you can use exo-utils or pcmanfm or thunar file manager

install them from software center


How to install Ubuntu from casper/filesystem.squashfs with chroot?

There is other way to do it, as envisioned by Ubuntu team.
Starts with Ubuntu Base, then you go on to install everything. No need for filesystem.squashfs from ISO.
Roughly follow my answer here:
https://askubuntu.com/a/1293305/1080682
Instead boot from other LiveCD or network boot use your current Ubuntu, skip formatting boot permission, just edit bootloader, and use Ubuntu Base squashfs, then APT to install whole desktop.
Instead putting script in autoinstaller, you can execute it in your Terminal/CLI. Just be careful with what gets executed in and outside chroot.
Since I typed this in answer instead comment (early morning) here is rough step (for exact commands see link):

boot your current OS
download Ubuntu Base squashfs (actually tar.gz) - http://cdimage.ubuntu.com/ubuntu-base/releases/
prepare partition for new OS
unpack the file system to new partition
chroot to add kernel (linux-image-generic), users, password, group membership setup neworking, etc, see link for few extras and explanation why
in your case you can run any other APT install commands while in chroot (eg ubuntu-desktop) - this is optional, can be done after reboot from CLI
if you need to do this offline, you can mount your ISO, and install packages that are on it using dpkg - this can also be done from CLI after reboot
update your grub with a new entry that points to new partition/OS boot files
reboot

P.s. Sorry got posted before finishing typing


I am using 3d modeling softwares. Can Ubuntu 13.10 is good for me....?

Using a compatibility layer like Wine you may be able to run them on Ubuntu. But they can be really instable and lack some of the features the have on a real Windows.

There are many opensource alternatives for such programs, like GIMP (The GNU Image Manipulation Program), which you could use instead of Adobe Photoshop, or Inkscape instead of Illustrator. I'm sure you'll find an alternative for each of the programs you're using on Windows. You can get them easily via the Ubuntu Software Center.

As for your Radeon, just try using Ubuntu form bootstick or DVD. (this won't install it, it's just a Ubuntu started from an external disc.)


Creating Point Clouds with Gimp
We have no idea how Photosynth works. With The Gimp
sudo apt-get install gimp

you can create point clouds very easily:
Load a picture with Gimp:

Reduce Colours
Choose Image -> Mode -> Indexed from the menu and then reduce to black and white 1-bit palette using dithering:

Point Cloud Result


node throw err; TypeError: undefined is not a function ubuntu 12.04

For anyone having this problem, I end up installing nvm through:

npm install nvm

And then used nvm to install node v0.8:

nvm install v0.8.1

And that solved the problem for me.


Apt can't find package libasound2-dev 20.04 arm64

I noticed that some of the files in /var/lib/apt/lists/ were zero size, so I ran:

sudo apt-get clean
sudo apt-get autoclean
sudo rm -rf /var/lib/apt/lists/
sudo apt update

Many of the zero size files were much larger and running apt search libasound2-dev yielded the expected result.


nvidia GPU: additional driver is missing

The driver is installed and is available for both GPU's as you can see in your terminal output.
Both GPU are using nvidia kernel module.
There is nothing to worry about.
The GUI tool is not too good generally and is not designed to deal with more than one Nvidia GPU.


Run Boot-Repair, but when asked "Do you want to activate [Backup and rename Windows EFI files]?", answer No.
Then in your BIOS (UEFI firmware), set Ubuntu as default entry.

Now using Windows should not mess up the boot any more.


How to identify game controller for SDL2 in Ubuntu?

The GUID is an SDL2 specific ID, there is no direct way to get it with system tool. The GUID is build by squishing the bus, vendor, product and version numbers into a single value, you can see it here:

http://hg.libsdl.org/SDL/file/a9d1c47bb1aa/src/joystick/linux/SDL_sysjoystick.c#l117

One way to get it is by reading it from SDL. The following program does that, compile it with:

gcc -o sdl2-joystick sdl2-joystick.c `pkg-config --libs --cflags sdl2`

Save the following as sdl2-joystick.c:

#include <SDL.h>

int main()
{
  SDL_Init(SDL_INIT_JOYSTICK);
  atexit(SDL_Quit);

  int num_joysticks = SDL_NumJoysticks();
  int i;
  for(i = 0; i < num_joysticks; ++i)
  {
    SDL_Joystick* js = SDL_JoystickOpen(i);
    if (js)
    {
      SDL_JoystickGUID guid = SDL_JoystickGetGUID(js);
      char guid_str[1024];
      SDL_JoystickGetGUIDString(guid, guid_str, sizeof(guid_str));
      const char* name = SDL_JoystickName(js);

      int num_axes = SDL_JoystickNumAxes(js);
      int num_buttons = SDL_JoystickNumButtons(js);
      int num_hats = SDL_JoystickNumHats(js);
      int num_balls = SDL_JoystickNumBalls(js);

      printf("%s \"%s\" axes:%d buttons:%d hats:%d balls:%d\n",
             guid_str, name,
             num_axes, num_buttons, num_hats, num_balls);

      SDL_JoystickClose(js);
    }
  }

  return 0;
}


Can't connect to Wifi 5GHz with Broadcom Corporation BCM4311

5GHz is NOT supported by broadcom-wl or any other driver choice. Sorry, but look here


To change network name back use nm-connection-editor.

To make wi-fi work again run Settings -> Wi-Fi -> ≡ -> Connect to Hidden Network... and select appropriate hot-spot connection.


Ubuntu does have touch support in the uTouch stack. However this touch support does not mean that the entire operating system can be used with touches and gestures.

Touch support has only recently been added and thus most applications do not provide touch support and can only be used with traditional input devices. I use my touch screen with a script that produces touch events but also simulates mouse events when there is only a single touch on the screen. Without this script I cannot use the touch screen in 99% of the applications available for Ubuntu.

So yes there is touch support, but if you want to use standard applications you're pretty much out of luck. Ubuntu cannot be used soley with touch.


WiFi stops working after waking from suspend with a Broadcom 43225

What does reboot do? Stop networking-manager, unload the module, reload the module and start nm.

I'm not sure, what the module-name for your driver is. I guess b43. You could do:

sudo /etc/init.d/network-manager stop
sudo rmmod b43
sudo modprobe b43
sudo /etc/init.d/network-manager start

and try if it helps.


How long does it blink ? If it beeps longer than 50sec? Can you press shift key after the acer screen to bring the grub menu up ? If you can bring up the grub menu press e and add acpi=off after quiet splash you can learn more here https://help.ubuntu.com/community/Boot-Repair


Is it possible to set transparency per window in Ubuntu 20.04?

There appears to be a non-standardized Extended Window Manager hint named _NET_WM_WINDOW_OPACITY which can be modified with the xprop tool.
xprop -f _NET_WM_WINDOW_OPACITY 32c -set _NET_WM_WINDOW_OPACITY \
  $(printf 0x%x $((0xffffffff * 60 / 100)))

where 60, in this case, is the number you want to modify to  the desired transparency
after executing the command your mouse pointer will turn into crosshairs and you need to click on the specific window you want to change its transparency on.

Making it a desktop shortcut

made a script with following content and saved it in ~/bin/xprop_transparency.sh

#!/bin/bash

read -p "Set transparency percentage ? [Enter for 100%]" mydectrans
# only accept 10 to 99, rest is considered 100
[[ "$mydectrans" != [1-9][0-9] ]] && mydectrans=100
# Convert decimal to 32bit hex representation
my32bhextrans=$(printf 0x%x $((0xffffffff * $((mydectrans)) / 100)))
# Execute the action
xprop -f _NET_WM_WINDOW_OPACITY 32c -set _NET_WM_WINDOW_OPACITY $my32bhextrans

made a desktop shortcut with following content and save it in ~/.local/share/xpropTransparency.desktop

Note: you have to expand ~ to full path , /home/paui in my case

[Desktop Entry]
Name=Set Window Transparency / Opacity
Exec=/home/paui/bin/xprop_transparency.sh
Terminal=true
Type=Application

made both files executable chmod u+x ~/bin/xprop_transparency.sh , chmod u+x ~/.local/share/xpropTransparency.desktop

how to check if your WM supports this hint:
Its not clear weather this method should be used to verify if your window manager supports it but you could try the following in a terminal window:
xprop -root _NET_SUPPORTED | grep -o _NET_WM_WINDOW_OPACITY
if it appears in the results, then you can be pretty sure that your window manager supports this. If it doesn't appear, perhaps it works, perhaps not, you'll just have to try and see...
Resources:

Article on setting this parameter
S/O answer setting opacity property within xlib
i3 Window manager enhancement issue discussion on the property
Another question/answer on same topic
Yet Another question/answer on same topic

Other software perhaps worth exploring

Glassy GNOME
pqiv image viewer with specific branch patch for transparent image with click through as described in this post


Mount and unmount errors when usb is connected in 12.10.

First, as root just unmount the device.  If there is a problem in the mount table this might clear it up.

As for mounting a USB, any type of mount command for devices generally requires root priv.  Once that happens, depending on the underlying permission of the USB filesystem, you still might have problems accessing it unless you are root.


If you follow the link you will find a number of deb packages, that should contain the patched kernel.
The easiest way to install deb package on Ubuntu is:

sudo dpkg -i package.deb

Just download amd64 versions of those packages. Please note that you may want both kernel image and it's headers.

P.S. 11.10 = Oneiric Ocelot


Well, it depends what you want to read it for?

Almost all programs just rely on $TZ being set in the environment or /etc/localtime being a link to a timezone file.  The C library will then automatically arrange for eg localtime() to return the correct time.

  1) How can I basically read above type of files

zdump -v /etc/localtime will show you what's inside the files.

These are compiled files not meant for humans to read.  apt-get source tzdata will give you the source they come from.

  2) Where is TZ environment variable defined in Ubuntu 10.04

It is not set by default.  Instead, /etc/localtime is a copy of the relevant zoneinfo file, and /etc/timezone is the name of that zone.

You can change them with sudo tzconfig or through the GUI.

You could set it in for instance ~/.env if you want a different personal default for yourself.


java.lang.UnsatisfiedLinkError: no nativeservices in java.library.path

apt-get install matlab-support

and follow the instructions. It will be quite enough.


my installer crashed while installing ubuntu on to my laptop

If the crash happens at a stage of setting "language, time zone or region", unplug the Ethernet cable to disconnect the laptop from the network/Internet. Then repeat the installation.


How to install MATE & Xfce desktops on Ubuntu 18.04

There are meta-packages available for both desktops (MATE and Xfce4) that install all needed packages to provide the desired desktop. You also should be able to select which desktop to start in the login screen.

MATE can be installed with the command as follows.

apt-get install mate-desktop-environment

Xfce4 can be installed with the command as follows.

apt-get install xfce4

For both desktops you may want to install further packages. To do so, use apt-cache search mate or apt-cache search xfce to list the available packages.


How to install MS Office 2010 in Virtual Box Windows VM

You can simply install MS Office inside the virtual machine as if it were a normal, standalone windows system. i.e. if you can access the installation files (either on CD/DVD or in an .iso or .exe) from inside the virtual machine you should be able to install Office like normal.

If you have an MS Office installation disc, you need to tell VirtualBox to acknowledge your CD/DVD Drive through the VirtualBox storage settings for your Win7 install. You may find help with this here.

You don't need Wine to install MS Office in your Win7 virtual machine, you just need the appropriate Office installation CD or .exe file to be accessible from the virtual machine itself.


Is it safe to rename special user folders?

You can rename the folders in the file $HOME/.config/user-dirs.dirs. Here's the default:

# This file is written by xdg-user-dirs-update
# If you want to change or add directories, just edit the line you're
# interested in. All local changes will be retained on the next run
# Format is XDG_xxx_DIR="$HOME/yyy", where yyy is a shell-escaped
# homedir-relative path, or XDG_xxx_DIR="/yyy", where /yyy is an
# absolute path. No other format is supported.
#
XDG_DESKTOP_DIR="$HOME/Desktop"
XDG_DOWNLOAD_DIR="$HOME/Downloads"
XDG_TEMPLATES_DIR="$HOME/Templates"
XDG_PUBLICSHARE_DIR="$HOME/Public"
XDG_DOCUMENTS_DIR="$HOME/Documents"
XDG_MUSIC_DIR="$HOME/Music"
XDG_PICTURES_DIR="$HOME/Pictures"
XDG_VIDEOS_DIR="$HOME/Videos"


This answer intends to give a possible way for satisfaction of the main question: Secure an Ubuntu OpenSSH server from Brute force attacks but without a firewall or SSH key pair?

Actually I prefer to use Firewall and SSH key pair and found the answer provided from Doug Smythies for really useful.

Protect SSH With Two-Factor Authentication

Two-factor authentication (2FA) is a type of multi-factor authentication. In this example 2FA confirming a user's claimed identity by utilizing a combination of these two different components:

Time based, six digit token code - authentication code. By default, these tokens are good for 30 seconds plus additionally added 60 seconds in order to compensate for possible time-skew.
User's password, which itself should be secure enough.

Actually when you have set PermitRootLogin no and the usernames are good chosen, for me, this method can be called 3FA.

Additionally, if the computer that you are logging into isn't hardened against brute-force login attempts, you can enable rate-limiting for the authentication module.

Let's begin:

1. Install dependencies

sudo apt-get install libpam-google-authenticator

2. Edit the configuration files

Edit /etc/pam.d/sshd and add this directive:

# Google Authenticator
auth required pam_google_authenticator.so

Add it in the beginning of the file. In this way the system will ask first authentication code and only then will ask password. Add it in the end of the file - system will ask first password.
Edit /etc/ssh/sshd_config and modify or add these directives:

ChallengeResponseAuthentication yes
UsePAM yes
PasswordAuthentication no           # You can leave this 'yes' it doesn't matter.

3. Activate the two-factor authentication for a user

Switch to the user who should use the two-factor authentication and type in the terminal:

$ google-authenticator Enter

Do you want authentication tokens to be time-based (y/n) yEnter
https://www.google.com/chart?chs=200x200&chld=M|0&cht=qr&chl=otpauth://totp/user@host%3Fsecret%3DE3CY3TNSNBXXXXXX

Your new secret key is: E3CY3TNSNBXXXXXX
Your verification code is 229999
Your emergency scratch codes are:
  19999711
  ...

Do you want me to update your "/home/user/.google_authenticator" file (y/n) yEnter

Do you want to disallow multiple uses of the same authentication token? This restricts you to one login about every 30s, but it increases your chances to notice or even prevent man-in-the-middle attacks
(y/n) yEnter

By default, tokens are good for 30 seconds and in order to compensate for possible time-skew between the client and the server, we allow an extra token before and after the current time. If you experience problems with poor time synchronization, you can increase the window from its default size of 1:30min to about 4min. Do you want to do so
(y/n) yEnter

If the computer that you are logging into isn't hardened against brute-force login attempts, you can enable rate-limiting for the authentication module. By default, this limits attackers to no more than 3 login attempts every 30s. Do you want to enable rate-limiting
(y/n) yEnter

This dialogue will generate an authentication file called .google_authenticator placed in the user's home directory. This file can be used also for other user's accounts if you want all of them to use same tokens. Further this file can be customized and also can be used for 2FA within Apache2, but that's another story.

4. Generate authentication codes

The secret key - E3CY3TNSNBXXXXXX - generated in the above step is used for authentication codes generation within some application as:

Commandline Authenticator
These desktop apps mentioned here
Extensions for web browsers described here
Google Authenticator for Android
Google Authenticator for iPhone/iPad

5. Example of usage

In this example is used the Authenticator extension for Chromium/Chrome:

6. Further reading

The main source of this answer: How To Protect SSH With Two-Factor Authentication;
Multi-Factor Authentication - how to enable SSH authentication using an OATH-TOTP app (the method described here) in addition to an SSH key pair.

EDIT:

In some cases there could has a difference between google's clock and the server's clock. Here you are few tips according this issue:

What is the command to update time and date from internet
Date: cannot set date: Operation not permitted
Linux : Add x seconds to the current date

  Unfortunately: If it's a VPS, you may not have permissions to do this... If you are using a VPS, contact your provider to handle this for you.

In case if your provider doesn't want to response to your requirements, the above set-up will work but with time-shift. Type date in your server's console and measure this time-shift. Then just work with this time-shift between the moment of authentication code generation and the moment of its use.


Is there any non-linear presentation software for linux like Prezi Desktop

Have a look at Sozi.

To use Sozi, you first create an SVG file containing everything you want to present in a graphics program of your choice, for example Inkscape. After you've created the presentation image, you open it with Sozi and define your animations.

Sozi will export the presentation in a standalone HTML file, viewable in most modern browsers.


Fastest way to check for bad sectors in HDD?

You have to check some SMART utilities.

You can use "Disk Utility" (aka palimpsest or gnome-disks depending on the Ubuntu release) for this.

In command line I suggest you install the smartmontools package (sudo apt install smartmontools) and play around with smartctl.

Example:

sudo smartctl --all /dev/sda


How is a device managed when not in /etc/network/interfaces on Servers?

I don't know if your setup is anything like mine but if so it could clarify.

I am behind a NAT router with port 80 open and forwarded to internal IP 192.168..

I have a static external IP and I have not configured my network interfaces file.

Upon install Ubuntu configures the network interfaces file to display a static IP on eth0

I then have nginx so when the traffic comes to my external IP my router sends it to my server and then nginx takes care of the rest.

Hope this helps :)


Why I can not umount partition, and why it is busy

You should always run data recovery operations from a live CD.

Once you deleted the files, the physical space on the hard drive is available to write more data, such as tmp files. If the data is over written you will not be able to recover.

In addition, it is usually best to work on a copy of the hard drive.

From your error message

umount: /: device is busy.

/dev/sda6 is mounted as root and you will not be able to unmount it.

If you wish to see what is using the hard drive, you can always use lsof

sudo lsof /dev/sda6

See also - https://help.ubuntu.com/community/DataRecovery


Is there a way to start just an app on secondary screen?

So the issues is with the bar moving to the secondary screen? Try this maybe:
https://i3wm.org/docs/userguide.html#_tray_output

Or if you want specific applications on specific screens you can try this: https://i3wm.org/docs/userguide.html#workspace_screen


How do I compute the mean from ASCII file data in bash?

Obligatory GNU datamash version

$ datamash mean 1 < file
2.6666666666667

ASIDE: it feels like this really should be possible natively in bc (i.e. without using the shell, or an external program, to loop over input values). The GNU bc implementation includes a read() function - however it appears to be frustratingly difficult to get it to detect end-of-input. The best I could come up with is:

#!/usr/bin/bc

scale = 6
while( (x = read()) ) {
  s += x
  c += 1
}
s/c
quit

which you can then pipe file input to provided you terminate input with any non-numeric character e.g.

$ { cat file; echo '@'; } | ./mean.bc
2.666666


How to get a resource file from a project in the Qt Creator?

I hope I can do without the conversion I have asked about. For my learning Qt Creator and Qt Designer, I think that the samples having *.ui files are enough for what I need.


is it possible to run the program that needs NVIDIA GPU?

Get the list of graphic hardware :
sudo lshw -C video

If the hardware has no NVidia GPU, you must run PYTorch with CPU
See : https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix/blob/master/docs/tips.md
Run a model on CPU with gpu_ids option set to -1:
--gpu_ids -1


OK, so your Windows crashed and you're trying to keep all of your data by installing Ubuntu...  Great choice!

These are the steps to follow:

(I will be saving this as I'm typing it so you can follow along)

Stop the panic! You're more likely to make mistakes when the adrenaline is flowing...
"Try Ubuntu" is just that: it does not leave any trace on your disk and you should not try to edit anything.
Install Ubuntu:

You have a broken system!  Do not install Ubuntu on the broken system!

Do you have an external USB hard drive? A 16GB USB stick? (8GB will do, but that's pushing it) Install Ubuntu on there and leave your broken Windows installation intact as a "data drive"

Follow the procedure in Install Ubuntu 14.04.1 LTS from the official Ubuntu site.

When you get to the screen "Installation type" click "Do something else"

You will recognise your Windows disk and your USB disk. (hopefully, don't panic!)

Create a swap file that is 2* the amount of RAM you have.

Allocate as much of the disk as you can afford to Ubuntu

Set that one as mount point /

Choose your windows disk as mount point /home (yes, a tiny little bit of your windows disk will be written to, but all of your data will still be there!)
Reboot into Ubuntu (you'll have to go into the BIOS to boot from the external USB disk or stick)
Now you have a working system with all of your data intact, so your first action should be to rescue as much of the data of your Windows disk.  (Which is not a disk any more: it's a "directory" called /home)

(It's technically not a "Directory" but a "Moint Point" under Ubuntu, but it serves the same purpose)

Now copy all of your data off your Windows disk onto somewhere else. (or better even: make two copies!)
You've got everything rescued?  OK!  Now you're ready to chuck the USB disk/key, boot the CD again, wipe everything off the internal drive, and re-format everything (especially format)  Use EXT4 as the "file system".


I can see forwarded port on canyouseeme website, but not on NMAP scan?

All fine. Canyouseeme shows port open on public address.
But when you run nmap, you in local network, so it shows port open on local ip.
If you run nmap from some remote server, it will show open only on public ip.


How to fix updated pip: RuntimeError: Python 3.5 or later is required

Looks like you upgraded pip to a version that doesn't support your Python version.

Uninstall pip and reinstall the system pip:

sudo apt purge python-pip python3-pip
sudo rm -rf /usr/local/lib/python2.7/dist-packages/pip
sudo rm -rf /usr/local/lib/python3.4/dist-packages/pip
sudo apt install python-pip python3-pip

Do not run pip install pip --upgrade

Note that you are using an unsupported version of Ubuntu, an unsupported version of Python (if Python 2) and a nearly unsupported Python (3.4 EOL June 2020). You ought to consider upgrading to a newer LTS. Ubuntu 16.04 would be a step up, 18.04 would be better, or wait for 20.04 next month. They all come with modern Python 3, and since 18.04 don't install Python 2 by default.


Should I use tasksel, tasks in APT or install regular metapackages?

In short: There is a difference between tasksel and apt-get installation process of tasks.

Looking at your example:

The apt-get way

sudo apt-get install 'lamp-server^' will evaluate to do the following:

Search the cache (package list files) for all "Task:" fields and get all with "lamp-server".
Install those packages the standard way:

sudo apt-get install package1 package2...

The tasksel way

sudo tasksel install lamp-server will look for a task called "lamp-server" in one of its configuration files under /usr/share/tasksel/**/*.desc:

Search the configuration files for a "Task:" field named "lamp-server".
Check if all prerequisites are available ("Key:" field) and remember them if not installed.
Choose method to select packages ("Packages:" field). If this ist "list" simply install following packages by name.
Read all following package names and pass it to previously selected method to generate package names.
Look for /usr/lib/tasksel/info/lamp-server.preinst. If it exists execute this script.
Install packages with apt-get using following command:

debconf-apt-progress -- apt-get -q -y -o APT::Install-Recommends=true -o APT::Get::AutomaticRemove=true install package1 package2 ...

Look for /usr/lib/tasksel/info/lamp-server.postinst. If it exists execute this script.

Conclusion

tasksel is more powerful in processing and selecting tasks. It can execute extra scripts before/after installation/removal of tasks. And the biggest benefit: You can modify tasks and create new ones very easily. It is not possible to edit an official package list file without drawbacks (valid signature).

Back to your first question:
In your special case both commands are almost equivalent (supposed you have enabled both APT::Install-Recommends and APT::Get::AutomaticRemove). Only difference is the extended package state of mysql-server and apache2 dependencies (set to "manually installed" with plain apt-get).

And what about metapackages?

If you don't make use of tasksel's features like selecting tasks (especially helpful at installation) and executing extra commands before and after some task blocks then a task is very similar to a metapackage. The difference is: A task is not registered as a package in APT cache.
So if you uninstall one task-dependency other task-deps aren't marked as auto-installed because they were explicitely installed. If you uninstall a metapackage the dependencies are removed with autoremove because their extended package state is "auto installed" (if not installed manually).
Note: All distributed tasks in Debian install a metapackage named task-TASKNAME.

Giving your example:

sudo apt-get install kubuntu-desktop

Will install the metapackage kubuntu-desktop. Dependencies are "auto installed".

sudo apt-get install kubuntu-desktop^

Will select all packages tagged with task "kubuntu-desktop". That are all dependencies of metapackage kubuntu-desktop. They all are marked as "manually installed".

sudo tasksel install kubuntu-desktop

Make sure X is installed before installing packages of task.
Will install the metapackage kubuntu-desktop. Dependencies are "auto installed".


Can't install apache2 for the first time

It seems you have a previous installation of apache in your system. I would first try apt-get install -f --reinstall apache2, -f to fix unmet dependencies. If that does not solve the problem, I would try apt-get remove --purge -s apache2. Purge will remove configuration files and the -s will make a 'test uninstall' (not remove anything), so you can check what packages would be removed (they should be only apache2 related packages, if you are unsure, post the output here). Then apt-get install apache2.


For step-by-step instructions, take a look at How to Setup a Dedicated Web Server

In this tutorial, you will learn about:

Install  Ubuntu Server operating system.
Install an OpenSSH server.
A LAMP (Linux, Apache, MySQL, and PHP) stack is going to be
installed.
Install a firewall to protect your server from unauthorized access.

For more information about FTP and bind DNS see Create a web server with Linux

Source:Net Tutts


Keyboard shortcut for "to the power of" (exponent) signs?

You can use specific set of  UTF-8 characters for entering sub/super scripts. Process is simple:

Hit Ctrl+Shift+U
Type out 00b2 ( that's zero-zero-b-2)
Hit space or Enter key and you will have a superscript for power 2.

Like this ². Of course you will have to substitute appropriate utf character code for other subscripts


As suggested by @Avi disabling the GPU solved this issue in my case.

I proceeded as suggested in this bug report and disabled the use of gpu for my chrome. For such, you just need to start it with the --disable-gpu flag.

You can also do as shown in this issue, by changing the settings. For this go at chrome://settings/ > Advanced and uncheck Use hardware acceleration.

As you can see, this seems to be an issue and both ways are just workarounds. Let's hope future versions fix this issue and this question/solution becomes obsolete.


Lxde - desktop file for opening files in lxterminal

Having Terminal=true is probably what breaks it. That tells the OS to open a terminal with the command in the Exec line. So set Terminal to false, and make sure you have the command string for lxterminal correctly formatted. Below is my desktop file for opening files in nano, another console text-editor.

[Desktop Entry]
Encoding=UTF-8
Version=1.0
Name=Nano Text Editor (Console)
Comment=Edit text files in a console using Nano
Exec=lxterminal -t Nano --command=/usr/bin/nano\ "%f"
Terminal=false
Type=Application
Icon=lxterminal
Categories=Utility;TextEditor;
StartupNotify=true
MimeType=text/plain;


External Hard Drives not Detected 12.04 LTS

It looks like it is detecting the drives. The 2Tb drive is /dev/sdb and the 250Gb drive is /dev/sdc according to your fstab -l above.

What you probably want to do is mount your disks. See: https://help.ubuntu.com/community/Mount/USB


Why can't I install 11.10 or 12.04, just on my Windows 7 machines?

Please read this carefully https://help.ubuntu.com/community/HowtoResizeWindowsPartitions
I did on my hp pavillion laptop.


To install python 2:

sudo apt install python

To install python 3:

sudo apt install python3

To see python version just start python

python

for python2

python3

for python3

You can also use:

python --version

or

python3 --version

To install the latest version, download it, unzip it and
install primary versions of python (the one you want by default) with:

sudo make install

and install secondary versions with:

sudo make altinstall

You can also follow this answer: How do I install Python 3.6 using apt-get?


Screen brightness malfunction after I put computer to sleep "suspend"

The problem was actually apple specific and is a known issue with Ubuntu on Macbooks.

Here is a resource on how to solve most of the problems with running Ubuntu on a macbook

A workaround for the backlight problem is also there:

  Look at comment 78 of this bug
  report

  Patrik Jakobsson wrote a kernel
  module that directly programs the
  backlight driver and it works!

  If you don't want to compile by yourself, follow these steps.

  Install Build-Essentials and headers

sudo apt-get install build-essential linux-headers-generic

  Download mba6xbl-dkms_0.0.3_all.deb and install it with

sudo dpkg -i mba6xbl-dkms_0.0.3_all.deb Note: Repeat this installation step each time you kernel gets updated.

  Load the module:

sudo modprobe mba6x_bl

  Log out and log back in. It should load automatically on next boot

I do not recommend downloading the (mba6xbl-dkms_0.0.3_all.deb) because it personally did not work for me, try a newer version:
mba6xbl-dkms_1.0.0_all.deb


Backlight can't be turn on in Acer Aspire 4736

Here is a solution that worked for me on Ubuntu 11.10 based on http://lare-india.blogspot.com/2011/09/ubuntu-upgrade-caused-blank-screen-on.html

Boot your laptop into Ubuntu.

Connect an external monitor or sit with your back towards a sunny window so the sunlight helps to illuminate the screen (a flashlight can help too).

Press Ctrl+Alt+T to open a terminal and type:
    sudo nano /etc/rc.local

You will be prompted for your root password, which was set when you performed the install. Type it in and hit Enter.

Press your down arrow key to move the cursor to the last line and hit Enter

Press your up arrow key once and type:
    setpci -s 00:02.0 F4.b=00

Press Ctrl+O to save and Ctrl+X to exit.

Now back in the terminal type:
    sudo nano /etc/default/grub

Find the line
    GRUB_CMDLINE_LINUX_DEFAULT = "quiet splash"
and edit it to
    GRUB_CMDLINE_LINUX_DEFAULT = "quiet splash acpi_osi = Linux"

Press Ctrl+O to save and Ctrl+X to exit.

Back in the terminal enter:
    sudo update-grub2

Once it completes, enter:
    sudo reboot

Your computer will reboot and when Ubuntu boots back up, you should be able to see the screen with no problems.


Is it a good idea to place app configuration files into "~/Ubuntu One" folder?

Generally, no, it's not a good idea to store configuration files in Ubuntu One. There was a session at UDS Q about this. I'm not sure where the audio stream is for that at the moment, or the Etherpad URL, but it's worth going through.

Most applications do not do the right thing with storing settings (configuration/preferences), state, and authentication details, and will often lump them all together. Also, even if all the apps did do this correctly, using Ubuntu One file synchronization is the wrong way to go about syncing such data. The upcoming u1db structured data storage and synchronization support, would be a much better way of doing the job.


Listeners disconnect from Icecast streams

Remedies depend on the root causing these disconnections. Likely we are faced with a bandwidth issue where listeners have a temporary drop, or the Icecast server is unable to provide streams at the rate demanded.

In the likely case that we can not easily increase overall bandwidth we can try to priorize all streaming connections e.g. in the router.
Alternatively we can try to gently increase the source timeout limits to disconnect clients in our ìcecast.xml configuration file in the section <limits>:

<limits>
    ...
    <source-timeout>10<source-timeout>
    ...
<limits>

Another method to avoid disconnecting clients it to define a low bitrate fallback mount in the <mount> section.


What should I do if the etcd installation hangs?

Looking at the logs it seems ok. Do you mean after printing the mentioned lines command prompt returns?
Run below command from the same directory and see if you are able to communicate.

./etcdctl set mykey "this is awesome"
./etcdctl get mykey

I used below steps for installation and it worked fine for me:

curl -L  https://github.com/coreos/etcd/releases/download/v2.1.0-rc.0/etcd-v2.1.0-rc.0-linux-amd64.tar.gz -o etcd-v2.1.0-rc.0-linux-amd64.tar.gz
tar xzvf etcd-v2.1.0-rc.0-linux-amd64.tar.gz
cd etcd-v2.1.0-rc.0-linux-amd64
./etcd


How to bulk convert .djvu files to .pdf?

You could use ddjvu, in a shell script. That said, the output PDFs are much larger (x10), which makes it hardly worth the effort. Ubuntu has no problem reading djvu files, but if your reason is good enough, use the following script.

Warning: Do not try it on 200 files right away. Run a test first on one or two small ones, to get the feel of how long it takes, and to make sure you are satisfied with the result. Press Ctrl + C, in case you want to stop the process.

#!/bin/bash
for i in *.djvu;
do ddjvu -format=pdf -scale=100 "$i" "${i/%.djvu/}.pdf"
done

...or the same, as a one-liner

for i in *.djvu; do ddjvu -format=pdf -scale=100 "$i" "${i/%.djvu/}.pdf";done

Simply run that in a folder with djvu files. The -scale=100 option downscales the output images, which makes the process much faster, and the output files' size more reasonable. Without it, the resulting PDFs were much larger then the originals, and took ages to convert, at least in my tests.


If by "flipped" you mean left-to-right this is normal Skype behaviour.

If instead it is flipped upside-down then you may try loading Skype with LD_PRELOAD=/usr/lib32/libv4l/v4l1compat.so skype.


Ubuntu 14.04 server sleeps after login screen

Have you tried adding the kernel options "acpi=off apm=off" to the GRUB_CMDLINE_LINUX_DEFAULT in /etc/default/grub?

Then run sudo update-grub and reboot your computer.

or else follow this link

https://superuser.com/questions/155881/how-do-i-prevent-ubuntu-from-putting-my-monitor-to-sleep


How could I see the keyboard layout in Xfce?

In XFCE it is possible to install Gnome Panel applications. If native panel application is not available in XFCE, you can consider adding the Gnome Panel Application that does the same job.


ctrl+Alt+F1 Will take you to the console login. Make some space from the console and reboot, you will be able to use the graphic environment.

You will need to move or remove files and folders. If you are not familiar with the command line, type:

man rm
man mv

df -h shows the disk space and du -sh afolder/* the space taken by files inside afolder


Grub : Windows 10 won't boot (invalid signature)

I see you've found a solution, and it's one of several I was going to suggest. (Disclaimer: I maintain rEFInd, so I'm not unbiased.) I do want to provide an analysis to suggest what may have gone wrong, though. Also, I have an important suggestion that may help you avoid future problems.

Based on your Boot Repair output, your first disk (/dev/sda, a 112 GiB disk) uses GPT, has an EFI System Partition (ESP), and has both Windows and Ubuntu (GRUB) EFI-mode boot loaders on its ESP. It looks like Windows is installed on this disk. You also have a second disk, /dev/sdf, a 932 GiB disk that uses MBR partitioning and has both Windows and Ubuntu partitions. It looks like Ubuntu is installed on this disk.

Ordinarily, the partition table type (GPT vs. MBR) is tied to the way the computer boots -- EFI/UEFI mode with GPT and BIOS/CSM/legacy mode with MBR. There are exceptions to this rule, but it's a useful starting point, especially for Windows. Because your computer has both GPT and MBR disks, this creates some ambiguity; but it looks like Windows originally booted in EFI mode from the GPT disk. Since everything used to work, I'd further hypothesize that Ubuntu was installed in EFI mode, too; but the Ubuntu installation booted from the ESP on /dev/sda to the actual installation on the MBR /dev/sdf. This is perfectly legal; however, it probably led to problems because of an assumption in a script somewhere. This is where I begin to move beyond fairly safe inferences into the realm of sheer speculation. In particular, my guess is that you did a software update in Ubuntu that ended up either breaking GRUB's ability to boot Windows. This can happen sometimes, especially if the Windows Fast Startup and/or Hibernate features are active. These features can cause filesystem damage, which can make the Windows boot loader seem to disappear or malfunction, either temporarily or permanently. Thus, it's imperative that these features be disabled, and I suggest you do so. See here and here for instructions on doing so.

You then exacerbated the problem by performing recovery actions that were designed for BIOS-mode Windows installations. This put a BIOS-mode Windows boot loader on the first sector of /dev/sda, among other things. Given that rEFInd worked, at least these attempts didn't damage anything further, just added useless cruft.

In any event, installing rEFInd bypassed the hash that is now the GRUB configuration, thus getting things working. If you're happy with rEFInd, you might as well keep using it. An alternative would be to try to fix the EFI-mode GRUB installation. Boot Repair can often do this, although your computer's odd mix of MBR and GPT, as well as traces of both EFI-mode and BIOS-mode GRUB installations, might confuse that tool. Thus, unless you're seriously unhappy with rEFInd, it's probably best to follow the adage "if it ain't broke, don't fix it." I do strongly advise you to disable Fast Startup and Hibernate in Windows, though; even if rEFInd can launch both Ubuntu and Windows now, if those features are active they could cause new problems in the future.


XInput Coordinate Transformation Matrix in xorg.conf

Figured it out by looking in the source:

Option "TransformationMatrix" "0.36 0 0.64 0 1 0 0 0 1"


So I copied in all of the ssh_host_* files (with and without .pub) and that seemed to do the trick.

I made sure the permissions and ownership were as indicated by the following answers:

https://superuser.com/a/532079/185661

https://askubuntu.com/a/17103/333103


SSH "Read from socket failed: Connection reset by peer" on Ubuntu AWS AMI for 16.04 Xenial

It turns out the IT department of my company had a network equipment misconfigured somehow.  Eventually it was fixed and now SSH works fine.


May I install temporarily programs during guest session

No the guest session does not have permission to install programs not even temporarily. If you log in as a user that installs packages you could say install bluefish before and they log in and it will be there. If you need to install software after say a student logs in it can be a bit tough. If you have https://help.ubuntu.com/community/SSH you could ssh into the machines the students temporarily log onto and isntall the programs using apt package manager on the command line and then you can uninstall it if you do not want it. https://help.ubuntu.com/community/AptGet/Howto