To answer my own question and maybe help others. I had some time to tinker with more recent kernels and found out that at least starting with kernel 5.10 all my woes are gone. Did not troubleshoot the issue with all kernels since, mind you, just found a working one and confirmed that problems had indeed been introduced with some iterations of the 5.8 version, in combination with the pair CoreELEC/Kodi 18.9 streaming from NFS. Problem solved for now then. Will try more recent kernels soon.


It has been decided that the Unity dialogs are not ready for prime time. They won't ship in Ubuntu 11.10 (see this changlog).


You will need to recreate those entries in alacarte (System -> Preferences -> Main Menu) and recreate your entries.

Typically the Wine menu will still be there - only hidden. Once you have alacarte open check to make sure you don't have a Wine entry already there:

If you do not click on Applications on the left column then select New Menu from the right. Enter the following details

Once you've named the menu click the Icon on the right of the New Menu Dialog to choose the Icon. I've included the path for the Wine image in the following screenshot:

After closing the new Menu dialog select Wine from the list on the left column. You'll need to recreate the following items:

You can recreate the Applications directory by following the steps above for adding the Wine Menu item. For Browse C: Drive You will need to add a "New Item" with the following fields entered:

Repeat this for both Configure Wine and Uninstall Wine Software

Finally to add back applications from Wine to the Applications folder navigate to the Applications folder on the left column and select "New Item" using the following example as a template:

Replacing the WINEPREFIX path with the path to your Wine Prefix (Typically /home/<USER>/.wine) and the path to the Applications executable.


When you reset your router, your computer has probably lost it's own IP address.
Open a terminal and type in ifconfig -a to see what your own computer IP address is.  Hopefully, if you're connected by Wi-Fi, you'll see a wlan0 and it will have received an IP via DHCP from your router.  IF your router is 192.168.1.1, your computer should have an IP such as 192.168.1.2 or .3.  The default gateway should be the IP address of your router.
If not, you'll need either set a static IP address, or check that DHCP is enabled on your laptop.
Alternatively, some routers may (loosely, probably don't), but try connect an ethernet cable and see if that allows you to browse to the router config page.
The following link should guide you to set a static IP address (it also shows how to check DHCP is enabled):
Switch To Static IP Address On Ubuntu 17.04 / 17.10


Why service restart fails with :-restart: Unknown instance:

A typical restart job will attempt to kill an old instance first. What is happening here is that there isn't an old copy to kill.


Moving Subdirectories Between Directories by Folder Name

Try following script

foo="/path/to/folder/containing/short-titled-directories"
bar="/path/to/folder/containing/extended-titled-directories"

for subdir in $foo/*
do
    if [[ -d "$subdir" ]]
    then
        folder_to_move=$(ls $bar | grep "$subdir")
        mv "$bar/$folder_to_move" "$subdir/$folder_to_move"
    fi
done


Unable to pair Magic Mouse and keyboard - only Unknown and "not set up"

I fixed the issue by removing the batteries from the wireless keyboard and from the magic mouse for 10+ seconds.

After that the devices are detected and paired successfully


Go to System -> Software Pacakges then select the radio button for Package from APT.  In the box type in isc-dhcp-server then click the red Install button below.


list of users under "lock/switch account"

This setting is controlled via gsettings. To disable showing other usernames in the panel, run the following in terminal

$ gsettings set com.canonical.indicator.session user-show-menu  false

Compare:


Why do the "Copy to" and "Move to" context menus in Nautilus only offer "Home" and "Desktop" as options?

11.10 onwards
Maybe this might work:
Nautilus scripts the bullets state, amongst others:

Move To... #selected files/folders to ... whereever you want. the script will check if you have write-permissions and if the file already exists
Copy To...

Pick the 2 scripts from the download link and just install those just to see if it works. It is fairly old but the way Nautilus works had not changed for as far as I know.


How to set power setting to performance?

Try this applet: Jupiter. It works fine for me.


yes you can install ADB and Fastboot.

First update Repository

sudo add-apt-repository ppa:phablet-team/tools && sudo apt-get update

then install ADB and Fastboot

sudo apt-get install android-tools-adb android-tools-fastboot

After installation check the ADB connection by

connect device via USB cable

Tpye adb devices and hit enter you will get an id of device connected to system.


In 16.04,spyder is spyder 2.3.8 for python 2 and spyder3 is spyder 2.3.8 for python 3 (source). In Zesty the package sources have Spyder 3.1.3, you can download and try to install it manually. From Zesty on, the package names will be less confusing here: python-spyder for spyder for python 2 and python3-spyder for spyder for python 3. However, no release has different versions of spyder in the package sources.


permission errors are happened due to simply PERMISSIONS

right-click on that file -> select properties -> permission tap
and set the options in an appropriate way

or

in terminal :

sudo chmod o+w /path/of/ur/file/file.pdf


Just save it in file some like function.sh and run it like:
bash function.sh

#!/bin/bash

customcommand () {
    sudo service nginx start
    sudo service mysql start
    sudo service php$1-fpm start
    # ... use switch case
    echo "Run v$1"
}

# this command execute version 7.1
customcommand 7.1

if it work, put this in .bashrc if it linux, or .bash_profile in mac


Finding out about synaptic-pkexec is easy:

w3@aardvark:~(1)$ locate synaptic-pkexec
/usr/bin/synaptic-pkexec
w3@aardvark:~(0)$ dpkg -S /usr/bin/synaptic-pkexec
synaptic: /usr/bin/synaptic-pkexec
w3@aardvark:~(0)$ dpkg -L synaptic | grep -E 'pkexec|man/|READ|doc'
/usr/bin/synaptic-pkexec
/usr/share/man/pt_BR
/usr/share/man/pt_BR/man8
/usr/share/man/pt_BR/man8/synaptic.8.gz
/usr/share/man/man8
/usr/share/man/man8/synaptic.8.gz
/usr/share/man/tr
/usr/share/man/tr/man8
/usr/share/man/tr/man8/synaptic.8.gz
/usr/share/man/fr
/usr/share/man/fr/man8
/usr/share/man/fr/man8/synaptic.8.gz
/usr/share/man/es
/usr/share/man/es/man8
/usr/share/man/es/man8/synaptic.8.gz
/usr/share/polkit-1/actions/com.ubuntu.pkexec.synaptic.policy
/usr/share/doc
/usr/share/doc/synaptic
/usr/share/doc/synaptic/copyright
/usr/share/doc/synaptic/README.tasks
/usr/share/doc/synaptic/NEWS.gz
/usr/share/doc/synaptic/README.Debian
/usr/share/doc/synaptic/README.supported
/usr/share/doc/synaptic/TODO.gz
/usr/share/doc/synaptic/README
/usr/share/doc/synaptic/NEWS.Debian.gz
/usr/share/doc/synaptic/changelog.gz
w3@aardvark:~(0)$ file /usr/bin/synaptic-pkexec
/usr/bin/synaptic-pkexec: POSIX shell script, ASCII text executable

Lots of stuff for you to read, including /usr/bin/synaptic-pkexec: POSIX shell script, ASCII text executable, which is short enough to include here:

#!/bin/sh
pkexec "/usr/sbin/synaptic" "$@"

But one question I have: Why, oh why, would you use a tool-in-a-box that you  don't understand?

However, on further reading of your poorly formatted Q, I surmise that you are trying to run synaptic from a non-GUI session. synaptic is a GUI tool. apt, apt-get, aptitude are command line tools for packages.


Which command gets run when I press the F1 key?

If you want to add a new Hotkey, for example when you press Shift+F1 call F1 commands, you will need an extra softwae as xbindkeys: xdotool or xte. I follow by using xte.

1. Install xbindkeys:

sudo apt-get install xbindkeys

2. Then install xte:

sudo apt-get install xautomation

The syntax for xte is like this: xte 'command key/mousebutton/xyCoordinates'

for examples:

To call a single key press:  xte 'key keyName'
To call a key combination:  xte 'keydown keyName' 'keydown secondKeyName' 'keyup keyName' 'keyup secondKeyName
And more! Read man xte

3. Find the name of a key: xbindkeys allows us to use the -k handle to find the name of a key or key combination.
Run xbindkeys -k  and press a key or key combination.

If you pressing Shif+F1 your output will look something similar to this:

"(Scheme function)"
    m:0x11 + c:67
    Shift+Mod2 + F1

The basic syntax of xbindkeysrc commands is like this:

"Command to run (in quotes)"
key to associate with command (no quotes)

so as you can see at above.

4. Create a file named .xbindkeysrc in your home directory:

touch $HOME/.xbindkeysrc

5. Now open .xbindkeysrc file.

gedit .xbindkeysrc

6. Bind key/key combination to another key/key combination:

So according to first example of xte syntax in step 2, we have this:

xte 'key keyName'

Ok, now combine this command with output of pressing Shif+F1 in step 3 and put in or type into .xbindkeysrc file that we opened in step 5. like this:

"xte 'key F1'"
Shift+Mod2 + F1

7. Save it and exit. Now you might notice your command doesn't work yet, that's because xbindkeys isn't running. To start it just run xbindkeys from a terminal. Your Shif+F1 should now start your F1 command!

According to this Q/A by Seth


How to make a home server using Ubuntu desktop?

Since you want a GUI based server (Which is an Ubuntu Desktop transformed into a awesome server ;) ) then just do the following steps before proceeding:

Update everything. Make sure you have already updated and upgraded the system

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

This way we are on the same page.
Make sure your wireless card is working correctly. If you happen to have a Broadcom based wireless card check the Installing Broadcom Wireless Drivers . If you have another it is very likely you will find the answer in askubuntu after searching for it with the name of the wireless card. Anyway I will assume that it is working correctly.
Install Samba Service and configure it by following the How to turn on Network Discovery and Share between computers with Samba
Installing SSH Service (mostly to help ease your way between 2 Ubuntu computers) by following the How to enable file sharing between two PCs? . You can also use putty in Windows if you like. A How to use SSH (ssh & rsync commands)? guide is also available.
If you are going to share the internet via the server. With this I mean, your router will connect to the server via a wired cable and then share the internet wirelessly to other computers then follow the How to Connect & Share your Internet Connection (Wired & Wireless) . Else if you want to do it via wired to another computer then Sharing Connection to other PCs (Via Wired Ethernet)
If you want to also share a printer with the other computers you can follow the What is CUPS server and how to share a printer (Locally or over a network)
Since you will be making a server, I also recommend installing SQUID PROXY if you happen to share the internet connection via the server. This will improve the bandwidth usage in general and it will feel like the internet is faster for all client PCs. To install follow the first answer in the What Updated Web Cache Servers are available (Caching HTTP Proxy) (By Rinzwind)

Remember to configure squid proxy in /etc/squid/squid.conf or /etc/squid3/squid.conf for site permissions, what should be reversed cached and other stuff.

After doing this 7 steps we should have a system that

Can share a folder with other computers in the LAN and they can see the shared folder without too much hassle, permissions or additional steps.
Can connect to the server via SSH or Samba sharing with no problem.
The server can share internet via a wireless or wired connection.
The server can now share a printer to all other computers including Windows like ones.

Let me know if any of this steps seems difficult to help you along the way.

Additional stuff can be to install xbmc and put all movies on the server. Then via the xbmc configuration options, enable web service so the rest of the computers can watch movies from the same server. There is a lot of stuff you can actually do with an ubuntu server.


What is the first number for in a 4-number chmod argument (such as `chmod 4555`)?

There's actually 4 attribute sets you can work with via chmod.

Special, User/Owner, Group, and Others in that order, when working with the four-number chmods, with that first number being special bits that can be set.

chmod 4555 equates to the following:

Set UID bit - Run the file as the owner regardless of which user is running it
User/Owner: Read, Execute
Group: Read, Execute
Others: Read, Execute

The s in your 'human readable' string for permissions indicates that the SetUID bit (explained below) is set.

Effectively, we can break down the four-number chmod permissions argument into specific descriptors as follows, and doing the math to determine what a 4 in the first section would be, a 5 in the next section, and so on.

Keep in mind that #### is Special User/Owner Group and Others in that order.

For Special attributes (the first number in a four-number chmod argument):

Set UID - Run file as owner regardless of the user running it (shows as s in the human-readable permissions string for User section) = +4 (--s under User/Owner)
Set GID - Run file as group regardless of the user/group running it (shows as s in the human-readable permissions string for Group section) = +2 (--s under Group)
Sticky Bit - EFFECTIVE ON DIRECTORIES ONLY - If set, only the directory's owner user and root can delete the directory, and only the file owner or root can delete files inside it. (shows as t in the human-readable permissions string for Others section)  = +1  (--t under Others)

For User/Owner, Group and Others attributes (the last three numbers in a four-number chmod argument):

Read = +4      (r--)
Write = +2     (-w-)
Execute (for files), or 'Enter Into / List Items' (for directories) = +1   (--x)


Increment Brightness by value using xrandr

Copy bash script below to a file called bright
Then mark it executable with chmod a+x bright

Bash Script
#!/bin/bash

MON="DP-1-1"    # Discover monitor name with: xrandr | grep " connected"
STEP=5          # Step Up/Down brightnes by: 5 = ".05", 10 = ".10", etc.

CurrBright=$( xrandr --verbose --current | grep ^"$MON" -A5 | tail -n1 )
CurrBright="${CurrBright##* }"  # Get brightness level with decimal place

Left=${CurrBright%%"."*}        # Extract left of decimal point
Right=${CurrBright#*"."}        # Extract right of decimal point

MathBright="0"
[[ "$Left" != 0 && "$STEP" -lt 10 ]] && STEP=10     # > 1.0, only .1 works
[[ "$Left" != 0 ]] && MathBright="$Left"00          # 1.0 becomes "100"
[[ "${#Right}" -eq 1 ]] && Right="$Right"0          # 0.5 becomes "50"
MathBright=$(( MathBright + Right ))

[[ "$1" == "Up" || "$1" == "+" ]] && MathBright=$(( MathBright + STEP ))
[[ "$1" == "Down" || "$1" == "-" ]] && MathBright=$(( MathBright - STEP ))
[[ "${MathBright:0:1}" == "-" ]] && MathBright=0    # Negative not allowed
[[ "$MathBright" -gt 999  ]] && MathBright=999      # Can't go over 9.99

if [[ "${#MathBright}" -eq 3 ]] ; then
    MathBright="$MathBright"000         # Pad with lots of zeros
    CurrBright="${MathBright:0:1}.${MathBright:1:2}"
else
    MathBright="$MathBright"000         # Pad with lots of zeros
    CurrBright=".${MathBright:0:2}"
fi

xrandr --output "$MON" --brightness "$CurrBright"   # Set new brightness

# Display current brightness
printf "Monitor $MON "
echo $( xrandr --verbose --current | grep ^"$MON" -A5 | tail -n1 )

Change MON="DP-1-1" to your monitor name, ie MON="HDMI-1"
Discover your monitor names using xrandr | grep " connected"
Change STEP=5 to your step value, eg STEP=2 is less noticeable

Call the script with:

bright Up or bright + to increase brightness by step value
bright Down or bright - to decrease brightness by step value
bright (with no parameters) to get the current brightness level

Hopefully the bash / shell commands can easily be googled for education but if any questions don't hesitate to ask :)
8 minutes after posting answer it occurred to me I could have used bc for floating point math and saved ~10 lines of code and the a lot of time from the 1.5 hours to write it shrugs.


How to get or configure IP-MIB in Ubuntu 12.04?

After installing SNMP and its daemon(sudo apt-get install snmp snmpd), you will need to edit the file /etc/snmp/snmp.conf and comment out the line containing "mibs:"

Within this file, change the line:

mibs :

to

#mibs :

Next, assuming you haven't done this already, you will need to obtain the full set of IETF MIBs. These files do not ship, by default, on Debian/Ubuntu systems due to licensing issues.

From the terminal(Ctrl-Alt-t), enter the following commands:

sudo apt-get install snmp-mibs-downloader

sudo download-mibs

Then, you will need to modify /etc/snmp/snmpd.conf.

To allow SNMP the system to receive queries on interfaces other than its loopback address. The lines for this should look like this:

#  Listen for connections from the local system only
#  agentAddress  udp:127.0.0.1:161
#  Listen for connections on all interfaces (both IPv4 *and* IPv6)
agentAddress udp:161,udp6:[::1]:161

Note that this will allow ANY system to query your machine. You will need to adjust this to limit SNMP access to your device.
You will now want to change your Read-only SNMP string from public to a custom string of your choosing, as below:

#rocommunity public  default    -V systemonly
rocommunity <My$ecret$tr1nG> (Don't use this example!)

Note: Removing -V systemonly from the line will allow access to the entire MIB tree and not restrict it to the system part of the tree.
Restart the SNMP daemon

sudo service snmpd restart

Finally, your SNMP query should now respond properly.

e.g.:

snmpwalk -v 2c -c <My$ecret$tr1nG> <MachineName> ipadd

IP-MIB::ipAdEntAddr.127.0.0.1 = IpAddress: 127.0.0.1
IP-MIB::ipAdEntAddr.192.168.1.7 = IpAddress: 192.168.1.7
IP-MIB::ipAdEntIfIndex.127.0.0.1 = INTEGER: 1
IP-MIB::ipAdEntIfIndex.192.168.1.7 = INTEGER: 2
IP-MIB::ipAdEntNetMask.127.0.0.1 = IpAddress: 255.0.0.0
IP-MIB::ipAdEntNetMask.192.168.1.7 = IpAddress: 255.255.255.0
IP-MIB::ipAdEntBcastAddr.127.0.0.1 = INTEGER: 0
IP-MIB::ipAdEntBcastAddr.192.168.1.7 = INTEGER: 1

The same query can be run using a GUI based MIB browser, as well. Personally, I prefer using SNMPb for my graphical queries. Once you have SNMPb installed, open SNMPb and navigate to the desired OID in the MIB tree. In your specific case, it would be 1.3.6.1.2.1.4.20 or iso-> org-> internet-> mgmt-> mib-2 -> ip -> ipAddrTable and perform a Get Bulk to receive the same data.


No graphics acceleration with an Nvidia GeForce 8500 GT

Much the same thing just happened to me (running 10.04) after the most recent Ubuntu kernel update.  I looked at glxinfo after seeing the same xsettings crash.

I did the following:

change to a terminal;
sudo service gdm stop
sudo apt-get remove nvidia*
./NVIDIA-Linux-x86_64-285.05.09.run to run the installer - I did not choose to add the 32-bit compatibility stuff on my 64 bit machine this time - there were a bunch of warnings about directories not existing;
sudo service gdm start
log in normally;
go to 'Preferences:Appearances:Visual Effects' and select 'Extra' - it worked this time;
re-import Compiz settings; and I am good to go again - until the next kernel update?

But after doing the above, when I rebooted I came up in low-graphics safe mode. Trying to run the nvidia-xconfig or nvidia-installer (I forget which), it complained that the 'nouveau' drivers were installed, and asked if I wanted to have the program try to disable that by inserting a file in /etc/modprobe.d/ .  I agreed. After rebooting, everything came up great so all's well.


Why is there a strange white border on Gnome Terminal?

It seems to be the shadow color with white code. its gives you no problem.

If you dont want that effect then you do it from CCSM.

open your terminal and type as sudo apt-get install compizconfig-settings-manager

then from your unity dash type as compiz and you can select it from the resulted menu.Now open that application then at Effects section  uncheck the window decoration option.


You can use the command below

if you use 32 system :

sudo /opt/lampp/manager-linux.run

if you use 64 system :

sudo /opt/lampp/manager-linux-x64.run


"synaptic: error while loading shared libraries: libept.so.1.aptpkg4.12"

You should reinstall libept1.4.2 since for some reason or other is not present in the /usr/lib directory. For doing so:

sudo apt-get --reinstall install libept1.4.12

You may check if it exist or not doing:

$ ls -l /usr/lib/libept.so.1.aptpkg4.12
-rw-r--r--. 1 root root 596740 jun 21  2012 /usr/lib/libept.so.1.aptpkg4.12


I dig for a while and find out that original solution for iPad charge is not good enough.
OpenSource community helped me to update it and currently this solution works for both i386 and amd64 architectures and supports lots of devices including iPad 3.

http://korenkov.info/pages/ipad-charge


Dropbox error - 'echo 100000 | sudo tee / proc/sys/fs/inotify/max_user_watches'

Edit your /etc/sysctl.conf file with your favourite text editor, e.g. nano:
sudo nano /etc/sysctl.conf

and append (or modify the value of) fs.inotify.max_user_watches=100000 at the end of the file as a new line.
As an option you can use the command sudo sysctl -w fs.inotify.max_user_watches=100000 or the command below, as described on the Dropbox help guide, the results will be the same.

From the advanced help guide from Dropbox

Monitoring more than 10000 folders
The Linux version of the Dropbox desktop application is limited from monitoring more than 10000 folders by default. Anything over that is not watched and, therefore, ignored when syncing. There's an easy fix for this. Open a terminal and enter the following:
echo fs.inotify.max_user_watches=100000 | sudo tee -a /etc/sysctl.conf; sudo sysctl -p
This command will tell your system to watch up to 100000 folders. Once the command is entered and you enter your password, Dropbox will immediately resume syncing.


Accessing my Windows 7 files from my Ubuntu account

Absolutely! Just open up Nautilus the file manager by clicking the Home Icon. On the left hand side of Nautilus you should see a drive symbol that will have a name relating to "windows" or the size of the partition such as "125GB filesystem" (where 125GB is the size of your windows partition). Click that to mount your windows partition and access all your files. A visual guide is located here.


Black screen after installation of Ubuntu 18.04

Enable nomodeset from GRUB boot menu
nomodeset is a kernel boot option. Adding the nomodeset parameter instructs the kernel to not load video drivers and use BIOS modes instead until X is loaded.
Safe Graphics Mode. A new option is added to the GRUB menu in 19.04 and later which will boot with nomodeset on. This may help you resolve issues on certain graphics cards and allow you to boot and install any proprietary drivers needed by your system.
Immediately after the BIOS/UEFI splash screen during boot, with BIOS, quickly press and hold the Shift key, which will bring up a GNU GRUB menu screen. With UEFI press (perhaps several times) the Esc key to get to the GNU GRUB menu screen. Sometimes the manufacturer's splash screen is a part of the Windows bootloader, so when you power up the machine it goes straight to the GNU GRUB menu screen, and then pressing Shift is unnecessary.
You will see a GNU GRUB menu screen that looks like this:

Press e to enter editing mode. This will bring up a GNU GRUB screen that looks like this:

Use the arrow keys to navigate when screen editing the above screen. Navigate to after the string on this screen that starts with root=. In this example screen the full string is root= followed by UUID= and a hexadecimal string as shown below:
root=UUID=bcf15ef2-a0b2-4753-9558-8399dd12a729

Immediately after this string replace ro quiet splash by nomodeset quiet splash. This change is only temporary — it will just be used once and GRUB won't remember it in the future. Press Ctrl+X or F10 to boot with the nomodeset option that was added. If you make a mistake, press Esc to go back to the previous screen.
Install proprietary graphics driver
Ubuntu 18.04 is bundled with a tool named ubuntu-drivers-common which detects and installs additional driver packages. The proprietary graphics driver can be installed with the following commands:
sudo ubuntu-drivers autoinstall
sudo reboot

The ubuntu-drivers autoinstall command installs drivers that are appropriate for automatic installation including their dependencies, and the proprietary graphics driver will also be updated automatically when an update is available. If your computer has an Nvidia GPU ubuntu-drivers autoinstall will install the proprietary graphics driver for it, otherwise if your computer has an AMD GPU its graphics driver is included in the default Ubuntu installation.
When installing a proprietary graphics driver, it is not necessary to uninstall the open source graphics driver. The two graphics drivers can be installed alongside each other allowing the open source graphics driver to be used as a fallback alternative in case there is a problem using the proprietary graphics driver.


How to uninstall the default screenshot app?

Yes, you can uninstall it by opening a terminal and typing:

sudo apt-get remove gnome-screenshot

Alternately, open Software Center and type "gnome-screenshot" in the search box on the top right; then click Uninstall (or Remove).


Do I need to install Bumblebee for Hybrid Graphics system to enable Optimus on Ubuntu 16.04?

Currently, you have (at the best of my knowledge) three possibilities regarding Nvidia hybrid graphics (the so-called Optimus technology) under Linux:

Bumblebee. While this project might seem dead, it’s not (discloser: I’m part of the dev team). It has been slowly developing for a very long time, because we were all quite busy, but things have gone better recently, and we received help from new contributors. The 4.0 version is on track, it’s mostly bug fixes and the primus backend becoming the default (most people won’t notice since they were already using it). Bumblebee allows you to run your desktop and display on the integrated Intel chip, while running selected applications on the discrete Nvidia card. It can use either nouveau or nvidia driver (given that they support your card, which they should both do), and relies on bbswitch for power management (with the option of using vga_switcheroo if using nouveau). On the performance side, because of how it works, Bumblebee is PCIe bottlenecked, which means you can not achieve very high framerates (which is not really usefull anyway) but also that you can never reach the full power of your dedicated Nvidia card. In case some of the display outputs on your laptop are wired to the Nvidia chip (often the case of HDMI on Lenovo laptop), Bumblebee allows you to use them, but it requires a bit of configuration, is probably far less than ideal and above all not tested since no any of Bumblebee devs own an affected laptop. Otherwise, Bumblebee works with either DRI2 or DRI3.
PRIME. This is the proper solution for this technology, and is implemented at the right level: drivers, kernel, Xorg… PRIME allows you the same setup as Bumblebee, however, due to legal concerns, only nouveau is supported. Outside of that, it has also some issues with tearing because of changes needed in the i915 driver. Also, nouveau still has a lot of issues regarding performances, so until it gets proper reclocking, you might have less perfs than in the Bumblebee + nvidia setup (Bumblebee + nouveau suffers from the same issue obviously). PRIME does not rely on bbswitch for power management, but rather use nouveau/kernel integrated one. PRIME also allows you to use outputs wired to the Nvidia chip quite transparently AFAIK. When running on DRI2, it requires a bit of configuration (depending on whether you also have Bumblebee/bbswitch installed, the exact amount may vary), but nothing outstanding. VDPAU is supported too in this mode (but only with nouveau driver again). When running on DRI3, it’s very seemless to use (so much that Bumblebee will probably gain support for this mode in the next release). However, you don’t get VDPAU support, and apparently no Nvidia outputs support either.
Reverse PRIME. Here, the idea is to use the Nvidia card for everything including the desktop, and only use the Intel chip as an output sink for the laptop display. This is supported by both nouveau (with the same performances issues as above) and nvidia (with the dedicated nvidia-prime tool under Ubuntu for instance). This means you don’t get powersaving at all (and get increased power consumption at all stages), but as with PRIME you can easily and fully utilize any display output. In this mode, you get the best of your dedicated card when using the nvidia driver. This is also the only configuration where you can get VDPAU working on the Nvidia chip using the nvidia driver. However, it has also some issues with tearing because of changes needed in the i915 driver. This mode only works with DRI2. In fact, this is for the same reason as why you can’t use outputs in PRIME+DRI3: Reverse PRIME is in fact the name of the support for using another card outputs (whether it’s Intel ones while running on Nvidia here or Nvidia ones when running on Intel above), and that currently does not work under DRI3.

Note that things like CUDA or OpenCL do not require any of these tools, just a bit of configuration, but Bumblebee as a mode to use them easily while still getting its other advantages.

PRIME and Bumblebee can cohabit when using DRI3, but under DRI2 or switching to Reverse PRIME requires a switch of configuration files and restarting the X server. So, depending on your needs, this is what I would advice:

If you don’t care about performances, but care about ease of utilisation (for external outputs mainly — if affected) and FLOSS, go for PRIME.
If you care a bit more on performances but often use your laptop in battery mode and don’t want to restart your X server all the time, go for Bumblebee.
If you care about performances and mostly use your laptop while plugged on AC (and don’t care about some extra W saving), take a look at Reverse PRIME using nvidia (you can use nvidia-prime to switch to Intel only mode when running occasionally on battery, but I’m not sure if the Nvidia card is turned off in this setup).


How to uninstall ubuntu-desktop in Bash on Windows

If you want to completely remove your Ubuntu instance, you can run the LXRun command from cmd/PowerShell (as per the docs):

lxrun /uninstall /full

If you then want to re-install your Ubuntu instance, just run the following from cmd/PowerShell:

lxrun /install

Update 2018-02-06

Update since a lot has changed since I wrote this answer ;)

The guidance above remains w.r.t. the original Ubuntu distro that WSL downloaded and installed when you first ran WSL in Windows 10 Anniversary Update.

In Creators Update and later, you enable WSL, and then install your distro of choice from the Windows Store. To remove a store-delivered distro, just right-click it's tile in the start menu and hit "Uninstall":


"sensors/sensors.h: No such file or directory"

Try installing libsensors4-dev, which appears to be the package that contains sensors/sensors.h on my 12.04 box

$ dpkg -L libsensors4-dev | grep '\.h$'
/usr/include/sensors/error.h
/usr/include/sensors/sensors.h


Understanding the Use% column of the df command output

The "Use%" is calculated this way:
Used / ( Used + Available ) * 100 %


Systemd service, Working Directory not change the directory

The systemd WorkingDirectory= setting defines on which directory the service will be launched, same as when you use cd to change a directory when you're working in the shell.

That doesn't mean that all the other paths (including that from ExecStart=) will now be relative to it, so you still need to fully specify the path to your script in that directive:

ExecStart=/home/someuser/somescript.sh

Perhaps you were thinking of the RootDirectory= directive instead? That directory uses the chroot command to switch the root of the filesystem seen by the process by the directory you specify, so from your use of / for the location of the script, that looks like maybe what you wanted... However, using RootDirectory= requires that you have a system image, with binaries and libraries under it. Like, you need to have a /bin/sh to run your shell script, and a /lib with a libc, etc. Typically you can't just use RootDirectory= to just about any directory that you like...

So my advice here in order to fix the issue you're seeing is to just update the ExecStart= to list the full path to your script.


why google chrome shuts down after closing the terminal?

You can use this command:

<your_app> & disown

In this case:

google-chrome & disown

Explanation:

  In the bash shell, the disown builtin command is used to remove jobs from the job table, or to mark jobs so that a SIGHUP signal is not sent to them if the parent shell receives it (e.g. if the user logs out).

Source


How to install the bcmwl-kernel-source package without an internet connection.

The bcmwl-kernel-source and dkms package and there required dependencies are on the livecd or liveusb disk that you installed ubuntu from.

Insert the livecd or liveusb disk, do not boot from the live disk then navigate to pool > restricted > b > bcmwl and copy and paste the bcmwl deb package to your desktop.

Now do the same with pool > main > d > dkms.

Now install the deb files. Open the terminal with CTRL+ALT+_T and:

cd ~/Desktop
sudo dpkg -i *.deb
sudo modprobe wl


Permission denied (publickey) after every time being disconnected

Your question is not clear but let me try to answer based on what I understood

You have 2 user... assuming ‘user1’ ‘user2’

If user1 needs to access user2
try copying the id_rsa.pub to user2 authorised_keys

Goto

cd .ssh
ls
cat id_rsa.pub

Copy the key

Then login user2

cd .ssh
ls
sudo nano authrized_keys

Paste the key you copied from id_rsa.pub

Then try connecting user2 from user1, you should be able to connect user2 without running into any issue

it should work...


windows folders unavailable after reboot

I recommend using the Disks app to do this.
Open the Disks app from the Ubuntu Dash. Then simply navigate to the disk and partition that you want to mount. Then proceed to click on the gear icon for the specific partition and select the "Edit Mount Options..." as seen here:

In the new window dialog, make sure that "Automatic Mount Options" is OFF, and select the checkbox "Mount at startup". This will do the trick.


All open Windows fade and stay faded even when responsive

The fading is done by the Fading Windows compiz plugin. For me I could re-color the windows that became stuck faded (or greyscale) by disabling the plugin.

I unchecked the Enable Fading Windows box and pressed back. Once the windows where fixed I went back and re-enabled this plugin.


/mnt points to an instance storage. Instance storage is tied to the instance lifecycle as pointed out in the docs:
http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/InstanceStorage.html#instance-store-lifetime

You can specify instance store volumes for an instance only when you launch it. The data in an instance store persists only during the lifetime of its associated instance. If an instance reboots (intentionally or unintentionally), data in the instance store persists. However, data in the instance store is lost under the following circumstances:

The underlying disk drive fails
The instance stops
The instance terminates

Therefore, do not rely on instance store for valuable, long-term data. Instead, you can build a degree of redundancy (for example, RAID 1/5/6), or use a file system (for example, HDFS and MapR-FS) that supports redundancy and fault tolerance. You can also back up data periodically to more durable data storage solutions such as Amazon S3 or Amazon EBS.


Creating a Portable Ubuntu 18.04 OS in a External SSD

From Suse [1]

  Method 1:

Insert the Linux OS Install CD/DVD
Reboot the computer
Enter the “Setup Menu”
Disable the internal hard drive
Save settings and exit
The computer will reboot so you can see the Post Screen
Push the appropriate key (F12 for Dell Laptops) to bring up the “One Time Boot Menu”
Select boot from CD/DVD
Install Linux OS (Follow your normal install procedure)
The only device that should appear is the external USB drive

  Note: Since the internal hard drive is disabled the Linux OS will have
  no choice, it will install all of the required components for the
  external USB drive to become a bootable device.

  When the install has completed:

Remove the Linux OS Install CD/DVD
Reboot the computer
Enter the “Setup Menu”
Enable the internal hard drive
Change the boot order to resemble
    USB Device
    Internal Hard drive
    CD/DVD
Save settings and exit
The computer will reboot so you can see the Post Screen (Let the system boot as normal)

  The machine will boot into your newly installed Linux OS and will have
  no knowledge or connection to the OS that is installed on the
  computers internal hard drive. Method 2:

Insert the Linux OS Install CD/DVD
Shout down the computer
Remove the internal hard drive
Start the computer
The computer will boot so you can see the Post Screen
Push the appropriate key (F12 for Dell Laptops) to bring up the “One Time Boot Menu”
Select boot from CD/DVD
Install Linux OS (Follow your normal install procedure)
The only device that should appear is the external USB drive

  Note: Since the internal hard drive was physically removed the Linux
  OS will have no choice, it will install all of the required components
  for the external USB drive to become a bootable device.

  When the install has completed:

Remove the Linux OS Install CD/DVD
Shut down the computer
Install internal hard drive
Enter the “Setup Menu”
Change the boot order to resemble
    USB Device
    Internal Hard drive
    CD/DVD
Save settings and exit
The computer will reboot so you can see the Post Screen (Let the system boot as normal)

  The machine will boot into your newly installed Linux OS and will have
  no knowledge or connection to the OS that is installed on the
  computers internal hard drive.


ubuntu 12.04 - 12.10
To add Guake to the Unity system-tray, you need to add it to the system-whitelist

Using dconf-editor (installed using the dconf-tools package), navigate as shown and add guake to the whitelist.
You then just start the app via guake & to make it appear in the system tray.
Make sure your guake properties (guake -p) has the system tray checkbox ticked:

13.10 and later
The ability to whitelist applications has been removed from Unity.
The argument the developers have is that applications should have been updated to support Ubuntu indicators.
There isnt a direct method to-do this without adding an additional PPA.
sudo add-apt-repository ppa:gun101/ppa
sudo apt-get update
sudo apt-get install guake-indicator

Search for "Guake indicator" in the dash to start the app-indicator


Can't compile tryone144's branch of compton on Ubuntu 20.04

The package asciidoc-base is missing. Install it by sudo apt install asciidoc-base.


Ubuntu Corrupts BIOS on Ryzen 3000 Machine

After lots of testing it turns out this is being caused by Secure Boot being enabled and CSM being disabled.  You change one of those BIOS settings and no more corruption of the BIOS during reboots.


From https://developer.ubuntu.com/en/snappy/build-apps/debug/

Testing a service

To test a service it must be installed first. Once it is installed, systemd's systemctl command can be used to see if the service starts and runs as expected, for example:

systemctl status snap.<name>.<appname>

Finding the logs

The journalctl command can be used to inspect the messages that the service sends to stdout/stderr, for example:

journalctl -u snap.<name>.<appname>

Services may log additional data to syslog (/var/log/syslog) or to custom log directories. Note that custom log directories must be in a path that the service can write to (usually SNAP_DATA).

Getting a core dump

To enable core dumps you have to configure a place to write them to through sysfs. For instance you can use

$ echo "/tmp/core.%e.%p" > /proc/sys/kernel/core_pattern

to ensure that your coredumps get written into the /tmp directory regardless of where CWD of the process that received a signal was.


How can I move the contents of my home folder to the home folder of another account?

Copy everything from the old home to the new home
When logged in as the new user make sure to be in the own home directory
cd

use rsync to get 'everything' from the old user (notice the slash at the end of the source directory, it is important, see man rsync)
sudo rsync -Havn ~monkey/ ~tiger

this is a 'dry run', and if 'it looks good', remove the n
sudo rsync -Hav ~monkey/ ~tiger

to really transfer the directory tree with all the files
then change ownership to the new user
sudo chown -R tiger:tiger .

Check after reboot, that it works as intended. If it fails, it is because you also copied some settings that created problems with the old user, and then you should copy only selected files. I would suggest that you avoid the hidden directories and files (starting with ., 'dot')
Safe method, do not copy hidden directories and files
When logged in as the new user make sure to be in the own home directory
cd
sudo rsync -Havn ~monkey/* ~tiger   # dry run
sudo rsync -Hav ~monkey/* ~tiger    # real copying
sudo chown -R tiger:tiger .         # change ownership

So if you want a safe method, this is the way to start. Maybe later on you can add some hidden files or directories, for example for the history of the web browser.


How can I switch back to an application without Launcher and alt+tab?

Pressing Super+W spreads all the windows out, so you might find it there.

If you don't, you can launch gnome-panel from the terminal (if it's installed) to get a GNOME 2 style taskbar, also seen in the screenshot above.


It's much too early for both projects to be able to answer this question.

However both use Zeitgeist heavily so you can probably guess in your head what can be possible.


The canonical location for the DNS resolvers on Linux is /etc/resolv.conf.

Since NetworkManager has taken over from ifconfig as the primary network management component, that file normally contains a single resolver, namely localhost:

$ cat /etc/resolv.conf
...
nameserver 127.0.1.1

NetworkManager, through dnsmasq, provides this local DNS resolver.  dnsmasq is also the DHCP-client (and has various other roles), hence 'knows' the upstream DNS resolvers.

You can use nmcli (the NetworkManager command-line interface) to query its settings:

$ nmcli dev show | grep DNS
IP4.DNS[1]:                             10.103.0.24
IP4.DNS[2]:                             10.103.0.23

In the GUI click on the network indicator, and select "Connection Information" from the menu.  The upstream DNS resolvers are listed there.


Ubuntu 20.04 Nautilus Quicklist / Jumplist

It still works almost the same way.
You just have to set:

DBusActivatable=false

See How do I add new locations to right-click menu of “Files” launcher in Ubuntu dock?


I haven't used eclipse for a while, but if I remember correctly, the console view uses red color for stderr.

If you want to execute your application and get red color for error messages, then print them to stderr instead of stdout.


What encryption module does Ubuntu use to provide Full Disk Encryption?

The encrypion module is LUKS.

The Linux Unified Key Setup or LUKS is a disk encryption specification created by Clemens Fruhwirth in 2004 and originally intended for Linux.

While most disk encryption software implements different and incompatible, undocumented formats, LUKS specifies a platform-independent standard on-disk format for use in various tools. This not only facilitates compatibility and interoperability among different programs, but also assures that they all implement password management in a secure and documented manner.

The reference implementation for LUKS operates on Linux and is based on an enhanced version of cryptsetup, using dm-crypt as the disk encryption backend.

LUKS Design:

LUKS is the standard for Linux hard disk encryption. By providing a standard on-disk-format, it does not
only facilitate compatibility among distributions, but also provides secure management of multiple user passwords.
In contrast to existing solution, LUKS stores all setup necessary setup information in the partition header,
enabling the user to transport or migrate his data seamlessly.

Source:

https://gitlab.com/cryptsetup/cryptsetup/blob/master/README.md

https://en.wikipedia.org/wiki/Linux_Unified_Key_Setup


How can I find out how often a program has started in Ubuntu?

The only solution that I could come up with is to wrap the programs you're interested in. That of course is only feasible if the list of programs you want to observe is short enough.

Look after the command dpkg-divert. It lets you move files under package control aside while still being managed by the packaging system. Something like this could work:

# dpkg-divert --add --local --divert /usr/bin/firefox.mylogwrapped --rename /usr/bin/firefox

Then link a log script to the original path like

# ln -s /usr/local/bin/mylogwrapper /usr/bin/firefox

Inside that wrapper do whatever you need to do and then exec /usr/bin/firefox.mylogwrapped "$@". You can access the name of the originally called binary with the $0 environment variable.

Good luck!


16.04 Ubuntu Software starts partially, closes after a couple of seconds

I was having the same issue. I went to 'System Settings->Details' and clicked on 'Install Updates', and now life is better.


I found this little snip of code about two years ago; it enables line-in throughput:

pactl load-module module-loopback latency_msec=1

This disables it: (It used to work on 10.04 but doesn't work in 12.04)

pactl unload-module module-loopback


Ok so this may not work for everyone but it was driving me crazy and I just couldn't find an answer and especially without being able to use mouse, and only using KB.
Anywho I found that ( for me ) on my kb I had a shortcut to disable mouse/touchpad. Fn + f3. If you have this option and you toggle it, it fixes the problem at least temporarily. It still bugs out on me from time to time but I just toggle it and it works.

-Hope it helps.


Unable to software updates for Ubuntu 18.04, showing error as Network is not available. But, I am able to access websites from browser

Try this from How to set proxy so that Software-updater works in 18.04?
    Ubuntu Software Updater and Aptitude don't use the HTTP proxy environment variables. They load all configuration files under /etc/apt/apt.conf.d.

Create a new configuration file named proxy.conf using a text editor (I used Pluma):

sudo pluma /etc/apt/apt.conf.d/proxy.conf
Add the following lines to set your proxy configuration:

Acquire::http::Proxy "http://user:password@proxy.server:port/";
Acquire::https::Proxy "http://user:password@proxy.server:port/";
Save your changes and exit the text editor. Now your proxy settings will be applied even to Software Updater and you can update your packages.


why i get a bad gateway error when trying to access U1 contact's webUI?

looks like problems with your connection ( page loads fine here ). Can you check it trough some proxy ( opera turbo should work too ).

have you tried it with other dns servers ?


Neat and fast way to count devices in home network

You can also try arp-scan (install using sudo apt-get install arp-scan on a terminal)

It returns MAC addresses and tries to find the manufacturer of the network adapter.

ie, sudo arp-scan --retry=8 --ignoredups -I eth0 192.168.1.0/24 (--ignoredumps and --retry=8 make the results more accurate) returns

Interface: eth0, datalink type: EN10MB (Ethernet)
Starting arp-scan 1.8.1 with 256 hosts (http://www.nta-monitor.com/tools/arp-scan/)
192.168.1.1 68:7f:74:a5:07:18   Cisco-Linksys, LLC
192.168.1.5 00:11:32:07:71:ac   Synology Incorporated
192.168.1.100   00:21:9b:f8:ec:1c   Dell Inc
192.168.1.117   00:12:fb:1a:88:8a   Samsung Electronics

4 packets received by filter, 0 packets dropped by kernel
Ending arp-scan 1.8.1: 256 hosts scanned in 1.377 seconds (185.91 hosts/sec). 4 responded

Give it a try.


Getting AT&T Velocity USB dongle on Ubuntu 16.04 server

I suggest that you edit the file /etc/network/interfaces to something like:

auto lo
iface lo inet loopback

auto enp0s20f0u2
iface enp0s20f0u2 inet static
address 192.168.1.25
netmask 255.255.255.0
gateway 192.168.1.1
dns-nameservers 192.168.1.1 8.8.8.8

I suggest a static address so that you can ssh and ftp into the server. Be sure to select a static address outside the range used by the DHCP server in the router, switch or other access point.

Get the system to read and use the changes:

sudo ip addr flush dev enp0s20f0u2
sudo ifdown enp0s20f0u2 && sudo ifup -v enp0s20f0u2

Did you connect?

ping -c3 192.168.1.1
ping -c3 www.google.com

It might take a reboot.


I've run into this question while searching details on OpenSCAD installation.
On the developer's site (where you can find the latest version), for Ubuntu 14.04, it is specified:

  $ sudo add-apt-repository ppa:openscad/releases
  (and then)
  $ sudo apt-get install openscad

I've just installed it this way and now begun drawing, discovering how it works (fine until now:) ).

Here is the link for other possible useful info> http://www.openscad.org/downloads.html#linux


gksu was the program that provided a GTK frontend for su and sudo. This way graphical applications were allowed to be run with root privileges.
  gksu is deprecated. It is removed from Debian, Ubuntu 18.04 and other newer Linux distribution version.

So, instead of using:

gksudo nautilus

Use:

sudo -H nautilus

or

nautilus admin://


Is it possible to move between desktops with mouse wheel?

If you are referring to 'scroll on desktop' that still works fine -

ccsm > Viewport Switcher > Desktop-based viewport switching, typically 'Move Next' - button 5, 'Move Prev' - button 4

It works ok with the default Wall & 2X2 workspaces though you might want to slow down a bit in Wall's settings.

It's not uncommon that some ccsm changes won't be realized until you restart compiz or do a log out/in, don't think this is one of them but you never know..

Rotate/cube may work for you, presently is quite broken for many with flashing of previous window when switching workspaces, still an open bug on that.


network doesn't work after adding second interface to netplan

The problem is because both your networks have gateways defined, and as such the netplan configuration is a little 'confusing' and will break your default routes to the Internet.

In netplan configurations, doing this will have conflicting 'default' route rules for your Internet traffic.

For network traffic headed out for a specific interface (to/from the Internet, in this case eno1), set the gateway4 field.  For all other network adapters, do not define gateway4 (in this case, enp4s0).  Then, either sudo netplan apply or reboot the system.

This will solve the routing headaches that you've observed.


java uses 100% CPU and cannot be stopped

jobs only shows the processes owned by the current shell (it's a shell built-in function -- and that's why you can't run it with sudo, that runs only executable programs). It usually does not show anything unless you started it in background. See help jobs.

You can check if there are any other java processes running with:

ps aux | grep java

This searchs for any running process which has the string "java" on its command line execution, including grep. You can eliminate grep using ps aux | grep java | grep -v grep, if you want.

Also, when a process is eating a lot of CPU, you usually can spot it using the program top, pressing P to order by %CPU:

You can also use M to sort by memory usage, and use the keys < and > to change the current field used to sort.

Now, WHY a process is taking much CPU is a really hard question to answer in a generic way. It may be doing useful stuff or it may be just stuck on an infinite loop, usually only by reading the source code you could find out which. If you were to consider the Java JRE that runs the Java plugins in your browser, its CPU load is highly dependant on the nature of the program you are running.


Ubuntu 13.04 HDMI resolution and display options incorrect

I did some more searching and came across this page https://wiki.ubuntu.com/X/Config/Resolution . This is the part that helped me :)

Adding undetected resolutions
Due to buggy hardware or drivers, your monitor's correct resolutions may not always be detected. For example, the EDID data block queried from your monitor may be incorrect.

If the mode already exists, but just isn't associated for the particular output, you can add it like this:

$ xrandr --addmode S-video 800x600

If the mode doesn't yet exist, you'll need to create it first by specifying a modeline:

$ xrandr --newmode

You may create a modeline using the gtf or cvt utility. For example, if you want to add a mode with resolution 800x600 at 60 Hz, you can enter the following command: (The output is shown following.)

$ cvt 800 600 60

# 800x600 59.86 Hz (CVT 0.48M3) hsync: 37.35 kHz; pclk: 38.25 MHz
Modeline "800x600_60.00"   38.25  800 832 912 1024  600 603 607 624 -hsync +vsync

Then copy the information after the word "Modeline" into the xrandr command:

$ xrandr --newmode "800x600_60.00"   38.25  800 832 912 1024  600 603 607 624 -hsync +vsync

After the mode is entered, it needs to be added to the output using the --addmode command as explained above.

I'm not sure if its a driver issue but I see that my sounds not either working on my TV via the HDMI and it does not pick up the HDMI sound driver in the sound settings.


How can I tell if multiple DHCP servers are running on Ubuntu 16.04?

If you want to know if there are multiple instances running, just check your processes in a terminal window - ps aux | grep dhcpd

To find out if there are more than one dhcp on your network and which IP they might have: on Windows, open a cmd and enter ipconfig /all. The block stating your IP 10.0.0.101 will tell you from which DHCP Server it got its information.

In general, if you want to know on an Ubuntu system where the lease comes from, do grep dhcp /var/log/syslog or if you have a console and your network interface would be eth0, you can do sudo ifdown eth0; sudo ifup -v eth0 in a terminal to see where the configuration info is coming from.


verifiying ubuntu iso with repository gpg-keys

The following steps allow you to verify the SHA256SUMS file for the downloaded Ubuntu iso:

Open Terminal (CTRL+ALT+T)
Import the keys from /usr/share/keyrings/ubuntu-archive-keyring.gpg via gpg --import /usr/share/keyrings/ubuntu-archive-keyring.gpg. You should see something like this:

gpg: keyring `/root/.gnupg/secring.gpg' created
gpg: key 437D05B5: public key "Ubuntu Archive Automatic Signing Key " imported
gpg: key FBB75451: public key "Ubuntu CD Image Automatic Signing Key " imported
gpg: Total number processed: 2
gpg:               imported: 2
gpg: no ultimately trusted keys found

The line

gpg: key FBB75451: public key "Ubuntu CD Image Automatic Signing Key " imported

shows you that you imported the GPG key for signing CD images (iso files) is the one with the following fingerprint:

Primary key fingerprint: C598 6B4F 1257 FFA8 6632  CBA7 4618 1433 FBB7 5451

and hence the ID FBB7 5451
Having imported the key you can then download the files SHA256SUMS, MD5SUMS, SHA1SUMS and their respective signatures *SHA256SUMS.gpg, MD5SUMS.gpg
Now you can use this command gpg --verify SHA256SUMS.gpg SHA256SUMS to check if the file SHA256SUMS is legitimate. If so then you should see something like this:

gpg: Signature made Thu 14 Feb 2013 06:38:41 PM CET using DSA key ID FBB75451
gpg: Good signature from "Ubuntu CD Image Automatic Signing Key "
gpg: WARNING: This key is not certified with a trusted signature!
gpg:          There is no indication that the signature belongs to the owner.
Primary key fingerprint: C598 6B4F 1257 FFA8 6632  CBA7 4618 1433 FBB7 5451

If the SHA256SUMS file has been altered then something like this will appear instead:

gpg: Signature made Thu 14 Feb 2013 06:38:41 PM CET using DSA key ID FBB75451
gpg: BAD signature from "Ubuntu CD Image Automatic Signing Key "

Basically, instead of following step 2 in the howto referred to in the question and getting the key from the keyserver, which may have been compromised, you use the key provided with your existing Ubuntu installation that you trust.


I installed windows 8.1 and ubuntu 14.10 only windows 8 boots

You encountered Redmond's idea that Windows should be the only OS on your hard disk. When you installed 8.1, the installation disk overwrote the boot manager and made Windows the default OS. There is a simple fix using Ubuntu Boot Repair. Go to the web page and download the iso image. Create a boot CD and then start your system with the CD. When you have repaired the boot manager, you should be able to boot into either OS.


Why do some commands execute properly only when the file being called is inside the working directory

The make command looks for the Makefile in the current directory by default.  For the first command you listed to work, you would need a Makefile in the current directory that contained a /home/me/Desktop/folderWithMakefile target.

If you want to run make in the context of a different directory (and hence pick up a different Makefile), you can use the -C option.  For example:

make -C /home/me/Desktop/folderWithMakefile [target]


gcc: not found

This indicates that gcc is not installed... to install that, do sudo apt install build-essential (essential tools for building packages).
Where did you get the driver anyway? As the fellow owner of a TL-WN722N, this repository worked for me: https://github.com/lwfinger/rtl8188eu
Building the driver will also need the Linux kernel headers, so sudo apt install linux-headers-generic.


ping uses something called ICMP packets, what are completely unrelated to TCP packets, such as the ones carrying an HTTP payload.

If you want ping (and other IP protocols that may depend on ICMP) to work, you have to configure the firewall to pass ICMP packets (perhaps filtering only those that are of interest to you, see below) and also the replies that are generated from these packets. (With the right firewall you may also be able to keep state, even though ICMP is essentially stateless. But this is not essential for ping to work.)

I was going to add the ICMP packet types you want to pass, but they are already discussed on security.se: https://security.stackexchange.com/questions/22711/is-it-a-bad-idea-for-a-firewall-to-block-icmp

In general, you want something like this (this is super hand-waving, with only the relevant details):

[Host A] <--(internet or untrusted network)--> [Firewall] <--[Host B]-->

The traffic between Host A and Host B is filtered depending on the nature of the traffic, and the state of that traffic. Sometimes Host B and the Firewall are the same. It doesn't really make much difference, as the Firewall itself is sort of a virtual host in some regards.

For different types of ICMP payloads can be sent from Host A to a network that it knows is on or behind the Firewall (it doesn't know which, generally). This traffic has to be passed by the Firewall, sent to Host B, and the reply from Host B has to be received as part of that conversation, NATted, and sent back out to Host A.

So, this traffic has to be passed going both ways, which sometimes matters to firewalls.

The first thing to check is if ICMP packets of the type we are interested in (your references here and in the comments says which ones we care about) are actually being passed by the Firewall and sent on to Host B. There will be some logging or interface of some sort that allows us to inspect and query the Firewall, I'm sure.

Once we know this traffic is passing, we need to make sure it is making it to Host B (or passed through to the IP stack on the localhost) and that the reply is also being passed.

The details of "how to make iptables work" is sort of beyond the scope of this question, but others might have more hints for you. Or perhaps those details may be found in another SO answer.

One trick is to save your firewall rules in a file, and create a new ruleset that is basically "pass everything in and log, NAT everything out and log" which you enable for testing. Then see if the pings are getting through at all. i.e., prove it is the firewall that is the problem.


An alternative would be xscreensaver.

Install it by:

sudo apt-get remove gnome-screensaver
sudo apt-get install xscreensaver xscreensaver-data* xscreensaver-gl*

You can configure it with xscreensaver-demo. This opens a GUI window which allows you to chose one of a huge number of different screensavers:

For your love to flames, I would recommend you the saver XFlame. It can also take a different picture as background and set it on fire.
If you would also appreciate a nice firework, you could try Fireworkx.


If you do not use nautilus file manager

If you use nautilus at all, stop here, and jump to the next section.

It looks like in your first attempt, the ppa was trying to overwrite a nautilus or nautilus plugin dependency on your system. Overwriting would be bad because it could break nautilus, so the system stops you. If you don't use nautilus, you could try removing it entirely:

sudo apt-get remove nautilus seahorse-nautilus
sudo apt-get autoremove # gets rid of nautilus extras hanging around
Try installing from ppa again sudo apt-get install nemo-seahorse

If you do use nautilus

You may be able to complete the install from ppa if you simply get rid of the seahorse-nautilus package followed by the autoremove command.

sudo apt-get remove seahorse-nautilus
sudo apt-get autoremove # gets rid of extra unused dependencies hanging around
Try installing from ppa again sudo apt-get install nemo-seahorse


Can I remove the KDE desktop from Kubuntu and just use Unity?

Solution for 12.04 in this article: Getting Back to a Pure Unity Gnome on Ubuntu

Backup your data and execute this in your terminal (to paste in terminal use ctrl+shift+v):

sudo apt-get remove akonadi-backend-mysql akonadi-server akregator amarok amarok-common amarok-utils apport-kde apturl-kde ark bluedevil cdparanoia cdrdao cryptsetup docbook-xml docbook-xsl dolphin dragonplayer freespacenotifier gnupg-agent gnupg2 gpgsm gpsd gstreamer0.10-qapt gtk2-engines-oxygen gtk3-engines-oxygen gwenview ibus-qt4 icoutils jockey-kde k3b k3b-data kaccessible kaddressbook kamera kate kate-data katepart kcalc kde-baseapps-bin kde-baseapps-data kde-config-gtk kde-config-touchpad kde-runtime kde-runtime-data kde-style-oxygen kde-wallpapers-default kde-window-manager kde-window-manager-common kde-workspace kde-workspace-bin kde-workspace-data kde-workspace-kgreet-plugins kde-zeroconf kdegames-card-data kdegraphics-strigi-analyzer kdelibs-bin kdelibs5-data kdelibs5-plugins kdemultimedia-kio-plugins kdenetwork-filesharing kdepasswd kdepim-kresources kdepim-runtime kdepim-strigi-plugins kdepimlibs-kio-plugins kdesudo kdm kdoctools khelpcenter4 kinfocenter klipper kmag kmail kmenuedit kmix kmousetool knotes konsole kontact kopete kopete-message-indicator korganizer kpat kppp ksnapshot ksysguard ksysguardd ksystemlog ktimetracker ktorrent ktorrent-data kubuntu-debug-installer kubuntu-default-settings kubuntu-desktop kubuntu-docs kubuntu-firefox-installer kubuntu-netbook-default-settings kubuntu-notification-helper kubuntu-web-shortcuts kvkbd kwalletmanager language-selector-kde libakonadi-calendar4 libakonadi-contact4 libakonadi-kabc4 libakonadi-kcal4 libakonadi-kde4 libakonadi-kmime4 libakonadi-notes4 libakonadiprotocolinternals1 libassuan0 libattica0.3 libbluedevil1 libboost-program-options1.46.1 libcalendarsupport4 libcln6 libclucene0ldbl libdebconf-kde0 libdlrestrictions1 libdmtx0a libencode-locale-perl libepub0 libeventviews4 libfile-listing-perl libflac++6 libfont-afm-perl libgadu3 libgif4 libgpgme++2 libgps20 libgrantlee-core0 libhtml-form-perl libhtml-format-perl libhtml-parser-perl libhtml-tagset-perl libhtml-tree-perl libhttp-cookies-perl libhttp-daemon-perl libhttp-date-perl libhttp-message-perl libhttp-negotiate-perl libibus-qt1 libilmbase6 libincidenceeditorsng4 libindicate-qt1 libio-socket-inet6-perl libio-socket-ssl-perl libk3b6 libkabc4 libkactivities-bin libkactivities6 libkalarmcal2 libkateinterfaces4 libkatepartinterfaces4 libkblog4 libkcal4 libkcalcore4 libkcalutils4 libkcddb4 libkcmutils4 libkde3support4 libkdeclarative5 libkdecorations4 libkdecore5 libkdegames5a libkdepim4 libkdepimdbusinterfaces4 libkdesu5 libkdeui5 libkdewebkit5 libkdgantt2 libkdnssd4 libkemoticons4 libkephal4abi1 libkexiv2-10 libkexiv2-data libkfile4 libkholidays4 libkhtml5 libkidletime4 libkimap4 libkio5 libkipi-data libkipi8 libkjsapi4 libkjsembed4 libkldap4 libkleo4 libkmanagesieve4 libkmbox4 libkmediaplayer4 libkmime4 libknewstuff2-4 libknewstuff3-4 libknotifyconfig4 libkntlm4 libkonq-common libkonq5-templates libkonq5abi1 libkontactinterface4 libkopete4 libkparts4 libkpgp4 libkpimidentities4 libkpimtextedit4 libkpimutils4 libkprintutils4 libkpty4 libkresources4 libkrosscore4 libksba8 libkscreensaver5 libksgrd4 libksieve4 libksieveui4 libksignalplotter4 libktexteditor4 libktnef4 libktorrent-l10n libktorrent3 libkunitconversion4 libkwineffects1abi3 libkwinglutils1 libkwinnvidiahack4 libkworkspace4abi1 libkxmlrpcclient4 liblastfm0 libloudmouth1-0 liblwp-mediatypes-perl liblwp-protocol-https-perl libmailcommon4 libmailtools-perl libmailtransport4 libmessagecomposer4 libmessagecore4 libmessagelist4 libmessageviewer4 libmicroblog4 libmpcdec6 libmsn0.3 libmuonprivate1 libmygpo-qt1 libmysqlclient18 libnepomuk4 libnepomukdatamanagement4 libnepomukquery4a libnepomuksync4 libnepomukutils4 libnet-http-perl libnet-ssleay-perl libntrack-qt4-1 libntrack0 libokularcore1abi1 libopenexr6 libotr2 libphonon4 libplasma-geolocation-interface4 libplasma3 libplasmaclock4abi3 libplasmagenericshell4 libpolkit-qt-1-1 libpoppler-qt4-3 libprison0 libprocesscore4abi1 libprocessui4a libqalculate5 libqapt-runtime libqapt1 libqca2 libqca2-plugin-ossl libqgpgme1 libqimageblitz4 libqjson0 libqrencode3 libqt4-designer libqt4-help libqt4-qt3support libqt4-scripttools libqt4-sql-mysql libqt4-test libqtassistantclient4 libqtglib-2.0-0 libqtgstreamer-0.10-0 libqtscript4-core libqtscript4-gui libqtscript4-network libqtscript4-sql libqtscript4-uitools libqtscript4-xml libqtwebkit4 libreoffice-kde libreoffice-style-oxygen libsocket6-perl libsolid4 libsolidcontrol4abi2 libsolidcontrolifaces4abi2 libsoprano4 libstreamanalyzer0 libstreams0 libsyndication4 libtag-extras1 libtaskmanager4abi3 libtemplateparser4 libthreadweaver4 libtimedate-perl liburi-perl libvirtodbc0 libweather-ion6 libwww-perl libwww-robotrules-perl libxml2-utils libxss1 libzip2 muon muon-installer muon-notifier muon-updater mysql-client-core-5.5 mysql-common mysql-server-core-5.5 ntrack-module-libnl-0 odbcinst odbcinst1debian2 okular okular-extra-backends oxygen-cursor-theme oxygen-icon-theme partitionmanager phonon phonon-backend-gstreamer pinentry-gtk2 pinentry-qt4 plasma-dataengines-addons plasma-dataengines-workspace plasma-desktop plasma-netbook plasma-scriptengine-javascript plasma-scriptengine-python plasma-widget-facebook plasma-widget-folderview plasma-widget-kimpanel plasma-widget-menubar plasma-widget-message-indicator plasma-widget-networkmanagement plasma-widgets-addons plasma-widgets-workspace plymouth-theme-kubuntu-logo plymouth-theme-kubuntu-text polkit-kde-1 printer-applet python-kde4 python-pyudev python-qt4 python-qt4-dbus python-sip qapt-batch qapt-deb-installer quassel quassel-data rekonq sgml-data shared-desktop-ontologies software-properties-kde soprano-daemon system-config-printer-kde systemsettings tasks-icons update-manager-kde usb-creator-kde userconfig virtuoso-minimal virtuoso-opensource-6.1-bin virtuoso-opensource-6.1-common xsettings-kde && sudo apt-get install ubuntu-desktop


Unable to install Ubuntu 20.04 on the machine and VirtualBox

UPDATE
I've found the issue here, this is because I have WSL2 enabled on Windows, for some reasons WSL2 and VMs cannot co-exist. After I disabled WSL2, the VM worked.
PS: WSL1 still works though, I think this is due to the fact that WSL2 is actually running as a VM.


lvm raid5 used only 3 of the 4 drives in my vg

I was experiencing the same issue today. The fix was to specify the number of stripes using -i 3. So, the working command should be:
sudo lvcreate -i 3 --type raid5 -l 100%FREE --nosync -n kingstorelv kingstorevg

I hope this can help someone in the future.


It's a bit complicated and I don't remember all the details.  However, the percentage is only a rough calculation and it needs to calibrate to be accurate.  Don't spend a lot of time worrying that 95% is bad and 100% is good nor that 55% is a whole lot different than 45%. It calibrates using discharge charge cycles to the realities of the battery to make it's estimate.

Try this to get it calibrated again. Unplug your computer and let it fully discharge until it shuts off.  Then plug it in and start the computer and let it charge up fully while it is running.  Don't be afraid to try that more than once.  See if that doesn't help.

3 years is a bit of time and new batteries are very inexpensive now-a-days.  Time how long it takes for your computer to shut off.  If the battery dies in 30 minutes you need a new one.  If it goes for a few hours, you're golden.  If it is weak, you might cycle it through a few discharge/charge cycles to see if the battery recovers. Particularly if it is NiCad batteries cycling it might help, not so much LiIon. I just ordered a new battery for my Asus 1005HA and it was $9.  Hard for an old guy to understand how they can be so cheep.


"HAL or DBUS not working" is to Gnome as "fuel pump not working" is to car, or at least close. gnome-power-manager isn't causing your problem, but its complaint is pretty good indication of what is. There are two prongs to the answer:

save the world

This is "should not happen" and if it has happened to you on an Ubuntu LTS upgrade, it likely has or will happen to someone else and Ubuntu wants to know about it. The command to use is

$ ubuntu-bug gdm

as documented at Reporting Bugs - HowTo.

save yourself

There was a time when I could claim detailed knowledge of the Unix process hierarchy and initialization routines; no longer. I find the dbus system quite mystical, and have to resort to:

extended, detailed, painful debug sessions, or
use the Microsoft "Nuke it from Orbit Approach to System Administration"®

Across this bandwidth limited channel, I'd recommend (2) and:

log in on the console Ctrl-Alt F1
nuke gdm, dbus and relations with sudo apt-get purge gdm dbus dbus-x11
reboot
from the console reinstall gdm and dbus with sudo apt-get install gdm dbus dbus-x11
reboot
compute in blissful harmony

Good luck.


You can install proprietary drivers by running in a terminal:

sudo apt-get update
sudo apt-get install nvidia-346 nvidia-prime

Then you will be able to switch between the integrated and discrete adapters after a reboot.


Bad archive mirror using PXE boot method

You can save your mirror information in your kickstart file:

curl --url http://192.168.1.1/ubuntu

You can specify the kickstarter file in the PXE boot line:

append vga=normal initrd=installers/jaunty/i386/initrd.gz ks=http://192.168.1.1/ks.cfg ksdevice=eth0 --

You should use apt-mirror to create a local copy of the ubuntu mirror. It is about 40GB and will take all night to generate. Please see questions directly about each of these things for further details.


How to synchronize bookmarks in Google Chrome between Ubuntu and Windows

I takes some time to synchronize bookmarks in Google accounts for some reason.

It is up to an hour or so.

Just wait a bit and you will get your bookmarks.


From the lengthy comments, the OP was able to resolve the problem by running :

sudo dhclient en3ps0
sudo install ubuntu-desktop


How to add Landscape monitoring to machine 0 in juju

A workaround is to do it manually:

juju ssh 0

then follow the normal guide:

https://help.landscape.canonical.com/GettingStarted/InstallingLandscapeClient/Draft


Disable Ibus from System Settings >> Language > Input Method>"Change it from ibus to none.

After that, do a killall ibus-daemon in terminal.


compiz CCSM crashed launcher- and windows-bar on Ubuntu 14LTS?

You've probably moved on. But since this comes up in a search, this worked for me:

rm -rf ~/.config/compiz-1/*

Might want to back up first.


Flash Player installed with update-pepperflashplugin-nonfree is not working on YouTube on Chromium

There is no problem with your installation.
Youtube videos automatically start in Chrome and Chromium with HTML5 now by default and as far as I know there is nolonger a workaround or other way around this. You used to be able to opt-out of the html5 trial under the youtube settings. All I can suggest is to use firefox instead or switch to a different video site.


Octave dependency problem on Ubuntu 16.04

16.04 is new and all packages are not ready to use in all servers. Using Main Server to download packages will solve your problem.

System Settings
Software & Updates
Select "Main Server" from "Download from" section


How to configure pam.d files for ldap over ssh on 12.04?

I was making an incorrect assumption about what the PAM modules did. I assumed that having an account in LDAP could actually cause a module to create the user on the system (an assumption probably influenced by my webdev background) much like it could also create the home directories (pam_mkhomedir).

Once I created the users locally using:

sudo adduser doej --disabled-password

I was able to login with the doej account in LDAP.

Incidentally, I found a solution using pam_exec that would allow me to dynamically create the users, too.


Creating a launcher entry about an app in home directory which needs "GTK2_RC_FILES" to run

Try it with the env command

Exec=/usr/bin/env GTK2_RC_FILES=/home/chris/.gtkrc-eclipse /home/chris/adt-bundle-linux-x86_64-20130522/eclipse/eclipse

See man env

NAME
       env - run a program in a modified environment

SYNOPSIS
       env [OPTION]... [-] [NAME=VALUE]... [COMMAND [ARG]...]


How to play webm (using the VP9 codec) in VLC?

VP9 requires VLC 2.2.

sudo add-apt-repository ppa:mc3man/trusty-media

sudo apt-get update

sudo apt-get install vlc vlc-plugin-*

https://forum.videolan.org/viewtopic.php?t=131211

I had this problem in ubuntu 14.04 and it got solved by installing VLC 2.2.


How do I install a specific video codec in Ubuntu?

a codec that works with CamStudio's desktop recording software.

Sadly, if the makers don't make available the codec for the community in binary (or even better the source) is unlikely that you can use the codec in any Linux distributions.

This codec is free for non-commercial use.
To use it in commercial projects buy a license here.

Here free means as no-cost per use.
Seems also that mplayer might support this codec. Is unclear if they mean that the can reproduce the codec or that they are able to codec raw video into this codec.
For people that are interested in adding codecs
Normally an apt-cache search <name of the codec> should suffice. In this particular case it returned non-useful results:
apt-cache search scls
texlive-latex-base - TeX Live: Basic LaTeX packages

Other codecs might have more luck.


CPU Running 50% or higher on HP Pavilion dv6

I ended up solving my CPU issue by removing Freenet from my system. Here is the forum I used to help me. https://ubuntuforums.org/showthread.php?t=792676


How to quickly and thoroughly use a LiveCD to test for hardware incompatibility?

The best way would be to run through the Ubuntu Friendly Test Suite.  Simply search for "Friendly" in the Apps lens, and run the "System Testing" app.  This already has all hardware related cases, and is a quick, easy way to test through all hardware enablement test cases.  More info can be found here: https://friendly.ubuntu.com/participate/


Translator offline for Ubuntu and free dictionaries, which of them?

GoldenDict
Designed as a StarDict successor, it supports its format, lots of other formats (Lingvo, Babylon etc), features tabbed browsing, morphology, live pronunciations, Wikipedia and so on. As a free software, it is constantly being improved and worked on.

Dictionaries
The most common dictionaries are Babylon (.bgl) but their problems is that are no longer officially supported.
So my recommendation is use the StarDict dictionaries. In this website you will find a library with hundreds of dictionaries.
How to install them: Open GoldenDict and select Edit -> Dictionaries -> Add then select the extracted folder and click Apply.
Donwload and Install

Download the source code
Uncompress it (with second click you'll see the option)
Open a terminal Ctrl+Alt+T
Enter cd uncompressed_folder
Enter the following commands in order:
qmake
make
sudo make install


No sound/audio after resuming from sleep

There are a few things you could try. First of all try restart the pulse audio daemon:

pulseaudio -k      # Kill the pulse audio process. It should restart by itself

You can also check if there are any messages related to pulse audio in the kernel ring buffer:

dmesg | grep pulse

If there any error messages, you could post them for us to take a look at.


What happens if a file listed for backup with rsync is in use?

In Ubuntu files that are opened by any program aren't handled any special but are accessible like any other file. You even can delete them (but that will only delete the file name entry, the file's data will still be there until the file is closed).

But depending on the program that is using the file the file's content may be invalid or out of sync with other file's content. So for a backup it is usually a good idea to make sure that all files are closed unless to know that this isn't a problem. Otherwise restoring your backup may get you an unusable or faulty system.


By doing this, you will no longer see the "ACPI PCC Probe failed" warning message at boot. But, your Ubuntu will disable the "Suspend" power feature and other onboard function keys for laptop, such as "Brightness", "Volume", and other shortcuts as well.

Let's start edit GRUB:

sudo nano /etc/default/grub

Find this line:

GRUB_CMDLINE_LINUX=""

Add "acpi=off", and it will looks like this:

GRUB_CMDLINE_LINUX="acpi=off"

Save and update GRUB:

sudo update-grub

You can now reboot.


Yes, it will.

Windows holds all your data in one big partition, which occupies the whole drive (more or less) - this needs to be removed as a single item, so your data will go.

Save it to a removable drive?


Yes, of course. Because you have some mistakes.

First of all, your script should look like:

#!/bin/bash
for User in $(cd /home;ls --hide=lost+found); do
echo "$User online since:"
who | awk '{ print "\tUser: "$1" - Terminal: "$2" - "$3" "$4}'
NOW=$(date +%s -d "Jan 1, 1980 00:00:01")
USR=$(lastlog |awk ' {print $1, ":",$5,$6,$9 } ' | grep $User)
USRDATE=$(echo $USR | cut -d ":" -f2)
(( USRDATE = $(date --date "$USRDATE" +%s) / 86400 ))
(( NOW = NOW/86400 ))
(( DAYS = NOW - USRDATE ))
done
FILE="/home/radu/watchuser"
OUTPUTFILE="/tmp/watchuser.out"
if [ "$1" == 'out' ]
then
FILE=$OUTPUTFILE  # you had an error here
fi                # and another one error here

And second, edit the crontab entries using crontab -e command (by default this will edit the current logged-in users crontab) and add the following line:

*/10 * * * * /home/Mike/watchuser >> /tmp/watchuser.out

...It doesn't need your name in front of the path to the script.

More about: http://en.wikipedia.org/wiki/Cron


Your software is complaining that it cannot find support for OpenGL.

This is most likely due to the fact that the drivers you are using don't have support for 3D. If your graphic card is Nvidia or ATI make sure that the drivers installed are the proper ones

For Nvidia.
For ATI


First of all you must check both discs (internal and external) for bad sectors or other problems.

Tools for this can be:

GsmartControl

Install by typing in console:

sudo apt-get install gsmartcontrol

Perform some tests to see if there's something wrong.

I also really advise you to read The Beginner’s Guide to Linux Disk Utilities

Also check /var/log/messages for errors or run dmesg after the copy of files failed.

If unmounting of the filesystem is needed, the best option is to use a livecd with a set of tools to help diagnose and repair a bad filesystem, for example:

Hirens Boot CD

Download and burn into a CD, boot that CD, and use the existing tools for Disc Diagnose and Repair.

Go to your discs manufacturer website, and look for any disc utility they can have, to scan for problems. I know that Maxtor and Samsung, have tools of their own.

Important question: Your external HDD and Pendrives work OK in other operating systems or in another PC?

This is important, as it can help rule out the defective hardware (the external drives, your USB ports, or your internal disc)


Doesn't boot after installing fglrx for ati 5650

In addition to the solution below, if you ever have this again, you can simply uninstall fglrx via terminal. I had a similar issue with my 4670 and fglrx. After I installed it and activated the driver, it would not boot.

Follow this Natty Installation Guide (there may be other methods around).

Once that is done, run:

rm /etc/X11/xorg.conf

and if you are logged in as your own account on terminal, just add sudo.

Good luck! :)


Only "Vulnerable" Flash Player version works

I have just downloaded the latest tar.gz file for 64bit linux from adobe.com (version 11.2.202.280). It seems to me that firefox takes the file from /usr/share/ubufox/plugins/, where libflashplayer.so is a symlink to /usr/lib/flashplugin-installer/libflashplayer.so.
So I have unpacked the package, and copied libflashplayer.so to /usr/lib/flashplugin-installer/. After restarting firefox, the flash plugin works, it no longer complains.
I use Ubuntu 12.04, and I have flashplugin64-installer installed, but I think it does not matter as long as you can find the location of the old plugin.
Good Luck!


Which is the best way to version a lot firefox's profiles?. git, dropbox/ubuntuone or better option

as was posted in an edit to your question

  Ok, new approach. I underestimate the process of firefox, because I was focus on sync server, so I found this link and statrt to wonder which of those files should I version to get the same functionality of firefox sync?.. so if no other options comes to solve this problem, perhaps this approach do the trick.


The entries in ~/.ssh/known_hosts are hashed and therefore can't be read by bash-completion, see this bug and a similar question on Unix.SE.

As a workaround there is this script (also see here for comments) for ~/.profile:

_complete_ssh_hosts ()
{
        COMPREPLY=()
        cur="${COMP_WORDS[COMP_CWORD]}"
        comp_ssh_hosts=`cat ~/.ssh/known_hosts | \
                        cut -f 1 -d ' ' | \
                        sed -e s/,.*//g | \
                        grep -v ^# | \
                        uniq | \
                        grep -v "\[" ;
                cat ~/.ssh/config | \
                        grep "^Host " | \
                        awk '{print $2}'
                `
        COMPREPLY=( $(compgen -W "${comp_ssh_hosts}" -- $cur))
        return 0
}
complete -F _complete_ssh_hosts ssh

Another attempt to work around this issue can be found in this answer on Unix.SE:

_ssh()
{
    local cur prev opts
    COMPREPLY=()
    cur="${COMP_WORDS[COMP_CWORD]}"
    prev="${COMP_WORDS[COMP_CWORD-1]}"
    opts=$(grep '^Host' ~/.ssh/config ~/.ssh/config.d/* | grep -v '[?*]' | cut -d ' ' -f 2-)
    COMPREPLY=( $(compgen -W "$opts" -- ${cur}) )
    return 0
}
complete -F _ssh ssh

Unfortunately I'm not able to test it right now, but you may just try them both. The second one looks much simpler to me, I'd expect it to run faster.


How to find system>administration>OS-uninstaller menu in Gnome?

Its not a program that is included in Ubuntu, you will need to add it but first you must add the repository that includes it.  It is not in the standard sources, so you will not be able to find it in the Software Center either.  While not an official Ubuntu program I have used it and it worked flawlessly.

To install it type the following in the terminal to add the PPA(personal package archive)

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

Then to get the package info on the PPA type

sudo apt-get update

to install type

sudo apt-get install -y os-uninstaller

the -y in the above command will automatically answer yes to any questions, this is a dangerous thing to do in most cases but fot this program it is fine.

to start the program you can look in the menu but as the terminal is already open you can just type

os-uninstaller

You can also do the last 3 step at once by entering

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

you can then use the program to uninstall Windows.

For more in depth info please see the Ubuntu Help page that was also my Source


Lubuntu 12.04 on powerbook g4 "Wireless Networks device not found (firmware missing)"

Please walk the computer over to the router to get a temporary wired ethernet connection. Open the terminal again and copy and paste this into the terminal:

sudo apt-get update
sudo apt-get install firmware-b43legacy-installer

Press Enter. After it's done, detach the ethernet, reboot and give us your report.


Administrator account on Ubuntu 18.04 machine

The following uses vi but you can use another text editor:
cd /usr/share/applications/
sudo vi eclipse.desktop


Back up virtualbox for a fresh install - while migrating to 64 bit

You can use the "Appliance Export Wizard" in VirtualBox to export your VM and then import it again on your reinstalled system. I'm using VirtualBox 4.1.8, but this feature has been around for at least a couple of versions.

Exporting a VM

Open VirtualBox
Go to the File menu and select Export Appliance
Select the virtual machine (VM) you want to export and click Next
Choose where you will save the exported VM and click Next
Review settings and click Export

Copy the exported VM to an external hardrive (or put it on a partition that will survive the reinstall). Once you've reinstalled, you can import the VM.

Importing a VM

Open Virtualbox
Go to the File menu and select Import Appliance
Choose the file to import and follow the rest of the prompts.


How do I enable syntax highlighting in nano?

The nano editor provides syntax highlighting for a few languages and scripts by itself. Check out /usr/share/nano/
nits@nits-excalibur:~$ ls /usr/share/nano/
asm.nanorc     fortran.nanorc   man.nanorc     ocaml.nanorc   ruby.nanorc
awk.nanorc     gentoo.nanorc    mgp.nanorc     patch.nanorc   sh.nanorc
c.nanorc       groff.nanorc     mutt.nanorc    perl.nanorc    tcl.nanorc
cmake.nanorc   html.nanorc      nano-menu.xpm  php.nanorc     tex.nanorc
css.nanorc     java.nanorc      nanorc.nanorc  pov.nanorc     xml.nanorc
debian.nanorc  makefile.nanorc  objc.nanorc    python.nanorc

Link them to your user's nano configuration file (present at ~/.nanorc, ${XDG_CONFIG_HOME}/nano/nanorc, or ~/.config/nano/nanorc, whichever is encountered first) with something similiar to this line:
nits@nits-excalibur:~$ cat ~/.nanorc
include /usr/share/nano/sh.nanorc

Now, syntax highlighting is enabled in nano for whatever file you linked (You could also link multiple files)

Note: Sometimes you might get a segmentation fault after you have edited your ~/.nanorc file. If such an error occurs, unsetting the  LANG environment variable helps. You can unset it with unset LANG in the terminal. (Solution obtained from here)
There are also other solutions if you are not satisfied with your bash highlighting. One example of such can be found here
You can also write include /usr/share/nano/* to the ~/.nanorc file to enable all languages to be highlighted if your nano version supports it.


Deb Repository & PPA Package Whitelisting Security

If you want to apt-mark hold for all current installed packages:

run dpkg --get-selections|grep -v deinstall |cut -f1|sed 's/$/ hold/g'| dpkg --set-selections

You can also set apt priorities. 0 is what you want. Wireguard should give you a good example:

sudo sh -c "printf 'Package: *\nPin: release a=unstable\nPin-Priority: 90\n' >> /etc/apt/preferences.d/limit-unstable"

Docker example:

$ cat /etc/apt/preferences.d/docker
Package: docker-ce
Pin: origin download.docker.com
Pin-Priority: 1001


Is it possible to install a .deb from a URL?

Edit: I didn't see your previous statement about knowing you could wget so this is a bit awkward... I'll leave this here for anybody who wants to know how to do this. Additionally the previous version of my answer didn't work but this version (at the expense of being somewhat longer) does:

TEMP_DEB="$(mktemp)" &&
wget -O "$TEMP_DEB" 'http://path.to/my.deb' &&
sudo dpkg -i "$TEMP_DEB"
rm -f "$TEMP_DEB"

You just need to alter the URL at the beginning. This could be aliased or written as a bash function.

I realise there are technical and security issues surrounding this (you don't get automatic updates, can the source be trusted, etc), but on a purely can-I-do-it basis, this might work.


This link describes the steps I took on my Dell Inspiron to cure the "no right click" issue:  Fix NO Right Click error

Summary:
  - install Gnome Tweak
  - Run Gnome Tweak,
  - select "Keyboard & Mouse"
  - In "Mouse Click Emulation" section, select "Area"


Ubuntu 12.10 doesn't boot after GRUB menu

First of all, we don't know did what state the update processes failed but as I understand (just guessing, not sure) there may be a "lack of permission" or "deadlock" problem which doesn't let boot process end up successfully.

On the other hand, that may be about the files required by linux kernel to load system and move_to_user_mode() or fork init(). If so; that probaby means your binaries are corrupted...

I hope you have a seperate partition for home directory but if not; here is my proposal:

Start your system with a live OS
Try to access your files
Make a backup of them
Reinstall your Ubuntu 12.10


Does GIMP pressure sensitivity work with a touchscreen laptop?

From what I understand, the screen should work like a mouse, but pressure sensitivity will not work if the hardware itself does not support it.


How to activate group chat in Skype 4.3 in Ubuntu 14.04?

If you actually mean group chat and not video calls, write

/msnp24

in any Skype chat window, and restart Skype. And all of your group chats from any other machines and chat history will become available.

INFO: here


How can I get back my router configuration in Ubuntu 16.04 server after shutdown?

You need to add again you firewall rules, but wait, don't shutdown after that.

There are two programs to save and restore rules: iptables-restore iptables-save . Save rules and check if it will be restored automatically on reboot. If not - run iptables-restore in rc.local or better make it managed by systemd


Automatically sleep and wake-up at specific times

rtcwake

The command that you are interested in is rtcwake:

  This  program  is  used  to  enter a system sleep state until specified wakeup time.

testing

To find the correct syntax that works for you try the following:

sudo rtcwake -u -s 60 -m mem

This should suspend the computer for 60 seconds before restoring.  The significant parameter is mem  You have several options you can choose - play to find the value that works best for you:

          standby
                 ACPI state S1. This state offers  minimal,  though  real,
                 power savings, while providing a very low-latency transi‐
                 tion back to a working system. This is the default mode.

          mem    ACPI state S3 (Suspend-to-RAM). This state offers signif‐
                 icant  power  savings  as everything in the system is put
                 into a low-power  state,  except  for  memory,  which  is
                 placed in self-refresh mode to retain its contents.

          disk   ACPI  state  S4  (Suspend-to-disk). This state offers the
                 greatest power savings, and  can  be  used  even  in  the
                 absence  of  low-level platform support for power manage‐
                 ment. This state operates  similarly  to  Suspend-to-RAM,
                 but  includes  a final step of writing memory contents to
                 disk.

          off    ACPI  state  S5  (Poweroff).  This  is  done  by  calling
                 '/sbin/shutdown'.   Not officially supported by ACPI, but
                 usually working.

          no     Don't suspend. The rtcwake command sets RTC  wakeup  time
                 only.

          on     Don't  suspend,  but  read  RTC  device  until alarm time
                 appears. This mode is useful for debugging.

suspend until a known time

A script (at the bottom of this post) could be used to suspend your computer and wake at a specific time:

syntax is suspend_until [hh:mm] for example

sudo ./suspend_until 07:30

Save the script as the name suspend_until and give it execute rights i.e.

chmod +x suspend_until

Cron

You can create a root cron job that calls this script to execute at a specific time in the evening and then awake in the morning:

sudo crontab -e

Now enter something like to run the suspend script at 23:30:

30 23 * * * /home/myhomefolder/suspend_until 07:30

suspend_until script

#!/bin/bash

# Auto suspend and wake-up script
#
# Puts the computer on standby and automatically wakes it up at specified time
#
# Written by Romke van der Meulen <redge.online@gmail.com>
# Minor mods fossfreedom for AskUbuntu
#
# Takes a 24hour time HH:MM as its argument
# Example:
# suspend_until 9:30
# suspend_until 18:45

# ------------------------------------------------------
# Argument check
if [ $# -lt 1 ]; then
    echo "Usage: suspend_until HH:MM"
    exit
fi

# Check whether specified time today or tomorrow
DESIRED=$((`date +%s -d "$1"`))
NOW=$((`date +%s`))
if [ $DESIRED -lt $NOW ]; then
    DESIRED=$((`date +%s -d "$1"` + 24*60*60))
fi

# Kill rtcwake if already running
sudo killall rtcwake

# Set RTC wakeup time
# N.B. change "mem" for the suspend option
# find this by "man rtcwake"
sudo rtcwake -l -m mem -t $DESIRED &

# feedback
echo "Suspending..."

# give rtcwake some time to make its stuff
sleep 2

# then suspend
# N.B. dont usually require this bit
#sudo pm-suspend

# Any commands you want to launch after wakeup can be placed here
# Remember: sudo may have expired by now

# Wake up with monitor enabled N.B. change "on" for "off" if
# you want the monitor to be disabled on wake
xset dpms force on

# and a fresh console
clear
echo "Good morning!"

N.B.

Change mem in this part of the script for whatever suspend method works for you:

# Set RTC wakeup time
sudo rtcwake -l -m mem -t $DESIRED &

You may also have to substitute the -u flag in place of the -l flag depending on whether your hardware clock uses UTC (-u) or local (-l) time.  Note that your hardware clock is different from the system clock you see in your operating system.

credit to redgeonline


You do not have to format the partition, just delete the files on the partition you don't need. It is already formatted as ext4. Assuming it is mounted at /media/disk:

sudo rm -rf /media/disk/*

(or just run Nautilus as root using gksudo Nautilus and delete everything in a nice GUI-way).

If you insist on formatting the partition, you need to unmount it and do

mkfs -t ext4 /dev/sda3

After that you'll need to update your bootloader so it sees that there's no OS on the second partition anymore and removed the entry from the boot menu:

sudo update-grub


How can I get a Byobu split to reload users permissions?

A process can change its uid and gid, but few processes do this and fewer let the user do this. Neither multiplexer, unfortunately, does either. With screen, apparently one can run a command on all windows using at (see this SU post). There seems to be no direct analogue of at in tmux, solutions usually include parsing the output of other tmux commands (a gist implementing this). Another solution is to synchronize all the windows, and run the command (from this SO post):

Ctrl-B :

setw synchronize-panes on

clear history


ERROR unrecognized command: juju generate-config

The command you're trying to run generate-config is not available in Juju 2.0, only in the 1.x series. A similar command is coming but hasn't yet landed. For now, you can find all the information you need to set up Juju here: https://jujucharms.com/docs/devel/getting-started


How do I install an equalizer in Rhythmbox?

As of 13/06/2012, this PPA seems to contain the latest version of the "10 Band Equalizer" (rhythmbox-plugin-equalizer) and its working great for me (on 12.04 and 14.04-64bit).

sudo add-apt-repository ppa:fossfreedom/rhythmbox-plugins
sudo apt-get update
sudo apt-get install rhythmbox-plugin-equalizer


Is it effective to decrease Gnome Shell's nice?

I'd add a swap file before trying an alteration of nice.

https://help.ubuntu.com/community/SwapFaq recomends having a swapfile or swap partition even if you have plenty of RAM, and the absence of swap space frequently causes freezes. Please generate a swap file, unless you use btrfs, in which case, a swap partition is recommended.

1g in the following line is the size of the swap file. You may change its size. 1GiB is the file name; if you change it in one place, change it everywhere in the following commands.

sudo fallocate -l 1g /mnt/1GiB.swap && sudo chmod 600 /mnt/1GiB.swap
sudo mkswap /mnt/1GiB.swap && sudo swapon /mnt/1GiB.swap
echo '/mnt/1GiB.swap swap swap defaults 0 0' | sudo tee -a /etc/fstab

However, if this is ineffective at solving that issue, you can change nice values for apps permanently. Set the default nice value of a particular user or group in the /etc/security/limits.conf file.


How to install Ubuntu on Toshiba Satellite c850-19z

This sounds like a case of Secure Boot, which is a security mechanism added by hardware vendors in collaboration with Microsoft to only allowed the system to boot from approved ISO images.

This mechanism can be a challenge when a user wants to install Ubuntu. Solutions depend on the UEFI in use, but it might entail disabling Secure Boot inside UEFI and then try again.

Be aware though that making changes in the BIOS is not without risk. If you decide to do it, it is a very good idea to write every changed setting down to be able to set it back afterwards.