ufw is a front-end for netfilter/iptables, the Linux mechanism for routing and filtering internet traffic.

ufw is completely optional and it's possible to create firewall and routing tables directly using the iptables commands.  Some people prefer the syntax of ufw, which is supposed to make it a bit easier.

ufw itself is not the firewall, it's a tool for setting the configuration of netfilter/iptables.  It is registered as a service because it needs to be run every time your machine starts up.  I don't believe it stays resident in memory after it has done this configuration.  "restarting" the service simply re-runs its scripts.  It is not unusual for things in Linux distributions to be registered as services even though they are merely scripts that run at boot or shutdown without staying resident in between.

If you use ufw you can't set your own iptables rules using your own scripts, as they will be overwritten when ufw sets its own.  This also means that ufw can conflict with other tools that set firewall rules.

If sudo ufw status returns "inactive", it means ufw has been disabled (and won't, for example, re-apply any rules at startup).  You need to ensure ufw is enabled with sudo ufw enable, though you also need to configure rules for this to have meaning.  If you are sure you have enabled ufw but it returns "inactive" there could be some other issue.

Note that "starting" the service doesn't enable ufw, it just activates the start-up script.  If ufw is disabled when the start-up script runs it won't do anything.

You can tell if your firewall rules have been applied at any given time using iptables directly:

sudo iptables -L
sudo ip6tables -L


Is there a way to indicate if an app is open in the current or another workspace?

Unfortunately, no. There is currently no option to allow having the marker for running windows have a different color if the window is not on the current workspace. The Ubuntu Dock is based on the Gnome Shell extension "Dash to Dock". Filing a feature request with the developers could cause them to consider adding this feature.


.cache/upstart/Unity7.log growing to consume the entire free disk space. Python cypto suspected

Manually downloading and installing python-cryptography and python-openssl from the Ubuntu package repository might be a safer alternative to adding the repository for a future distribution to your sources list.

I achieved this by downloading the appropriate packages from here and here, then installing them using dpkg:

sudo dpkg -i python-cryptography_1.7.1-2_amd64.deb
sudo dpkg -i python-openssl_16.2.0-1_all.deb
sudo apt-get -f install

Important: Read the output of the last command carefully. It threatened to remove a load of packages when I ran it, because dependencies weren't met - I initially tried to install python-openssl without python-cryptography.

Read more about manually installing packages:
How do I install a .deb file via the command line?

After a reboot my Unity log file is no longer increasing in size at a rate of 10 MB per second.


I just formatted my external hard drive, so why the is used space huge?

When creating ext4 fs, usually you should reserve some space for system daemons needs. Quote from mkfs man page:

Set the percentage of the filesystem which may only be
allocated by privileged processes. Reserving some number
of  filesystem  blocks  for  use by privileged processes
is done to avoid filesystem fragmentation, and to allow
system daemons, such as syslogd(8), to continue to function
correctly after non-privileged processes  are prevented from
writing to the filesystem.  Normally, the default percentage
of reserved blocks is 5%.

So by default mkfs keeps 5%, in case of 1Tb it may 50Gb. I don't know what % gparted uses by default.

As a summary

Please read this and this carefully.

In your case, as you wish use this hard not for root ( / ), but as audio/video/other_need storage, you can remove reserving of blocks using tune2fs utility.

tune2fs -r 0 /dev/sdxX

Quote from opensuse forum:

If you set the reserved block count to zero, it won't affect
performance much except if you run for long periods of time (with lots
of file creates and deletes) while the filesystem is almost full
(i.e., say above 95%), at which point you'll be subject to
fragmentation problems. Ext4's multi-block allocator is much more
fragmentation resistant, because it tries much harder to find
contiguous blocks, so even if you don't enable the other ext4
features, you'll see better results simply mounting an ext3 filesystem
using ext4 before the filesystem gets completely full.

If you are just using the filesystem for long-term archive, where
files aren't changing very often (i.e., a huge mp3 or video store), it
obviously won't matter.


How to control auto-generated grub entries for other operating systems?

Here is my inelegant solution.

Open /etc/grub.d/30_os-prober to edit.

Find the line where LPARAMS is defined and change its value to whatever you want appended at the end of the linux line in the grub menu entry. Include all desired parameters (including the root value), with appropriate spacing. As a precaution, leave the original LPARAMS line, but commented out.

Run update-grub.

This process will append your additions as parameters for every linux os that is probed for.
There is surely a more specific way to do this by adding custom logic to /etc/grub.d/30_os-prober, but I do not know how.


Follow this instructions on the following link about the synaptic touch pad drivers. As most of the laptops ships with the synaptic touch pads.


Trackpoint middle button not recognized by xev

The bugfix for this was merged into Linux kernel 4.13rc6. So it should be available in two to three weeks.


Please open a terminal and do:

sudo apt-get purge bcmwl-kernel-source

Reboot. Your ethernet should now be working. Next, do:

sudo apt-get update
sudo apt-get install firmware-b43-installer

Detach the ethernet, reboot once again and all should be working.


Can I make it so scroll bars extend to the very edge of the screen in lubuntu?

I know this might not the answer you are looking for, but just chose a different desktop theme and that should took care of it. If not, let me know, its been a while since i have used lubuntu, I would have to re-look at everything to further help out.


Increase storage for Ubuntu (under Virtualbox)

Run gnome-disks to format the new hardrive:

gksu gnome-disks

If it's not there, install gparted and run it to format the newly added hardrive as ext3 or ext4:

sudo apt-get install gparted
gksu gparted


If you are talking about the terminal emulator terminator, it does not need Java and it is installable from the main repositories. This is what you get when installing on a fresh 13.04 install:

terdon@oregano ~ $ sudo apt-get install terminator
Reading package lists... Done
Building dependency tree
Reading state information... Done

The following extra packages will be installed:
  libbonobo2-0 libbonobo2-common libbonoboui2-0 libbonoboui2-common
  libglade2-0 libgnome2-0 libgnome2-bin libgnome2-common libgnomecanvas2-0
  libgnomecanvas2-common libgnomeui-0 libgnomeui-common libgnomevfs2-0
  libgnomevfs2-common libidl-common libidl0 libkeybinder0 liborbit2
  libvte-common libvte9 python-gnome2 python-keybinder python-pyorbit
  python-vte
Suggested packages:
  libbonobo2-bin desktop-base libgnomevfs2-bin libgnomevfs2-extra gamin fam
  gnome-mime-data python-gnome2-doc python-pyorbit-dbg
The following NEW packages will be installed:
  libbonobo2-0 libbonobo2-common libbonoboui2-0 libbonoboui2-common
  libglade2-0 libgnome2-0 libgnome2-bin libgnome2-common libgnomecanvas2-0
  libgnomecanvas2-common libgnomeui-0 libgnomeui-common libgnomevfs2-0
  libgnomevfs2-common libidl-common libidl0 libkeybinder0 liborbit2
  libvte-common libvte9 python-gnome2 python-keybinder python-pyorbit
  python-vte terminator

As you can see in the output above, there is no java or JRE requirement and you can install terminator (which is a python program) directly from the Ubuntu repositories.

There are actually two terminal emulators with the same name. The one you tried to install does indeed need Java and if you are really sure you want that one, despite its being much heavier (java) and complicated to install, you can install a JRE with

sudo apt-get install openjdk-7-jre

I stress however, that installing jre to get a terminal emulator is ridiculous. As far as I can tell both terminator flavors have the same functionality but the one you want to install is simply much much much heavier on the system. Still, your choice.


Not possible. It's important to note here that you can do it with the OS on separate drive, and after selecting the option in the next screen you can select the drive you want to install to .
However This Does Not Leave the Other Drives Untouched!!
Ubuntu will add grub options for other OS, which in Ubuntu's case is usually a very stable and helpful practice. However in the case of zfs It bricked my Centos8 install by messing with /sysroot which had to be manually repaired from rescue mode, a long and arduous process.
I'm putting this here in case someone is considering any kind of dual boot scenario using destructive zfs on root option in Ubuntu Focal Graphical installer and happens to land here. I don't recommend it. Remove your drives first (or disable them in bios), or do a selective install and then install zfs manually. Even then it goes without saying fully back up your other systems first!


How to compress and download directory from remote to local?

You don't really need compression, if the problem is that there are many small files. Use tar to make an archive on Ubuntu, and instead of saving the archive to a file, send it to stdout (the default for Ubuntu's GNU tar when there's no file specified) and read the tar file on the other end:

ssh ubuntu-server tar c -C /path/to/target_directory . | tar xvf - -C /path/to/local_directory

Or use a smarter tool like rsync.


apache2 not starting after purge and re-install

In 14.04, the apache binaries are located in apache2-bin.

Since you are missing the binaries, you can try reinstalling that package along with apache2.

sudo apt-get install --reinstall apache2 apache2-bin

Then try starting apache again, (Although I believe apache will auto-start itself after installation)

sudo apache2ctl start


No desktop after installing graphic drivers?

Just log in, then right-click your mouse, then click change background, then click the all settings tab, then click Additional Drivers, then uninstall your video driver. Then reboot.


How to connect two personal computers using ssh?

Yes, you can.

First, make sure package openssh-server is installed on both of them. Then, fire up terminal and type:

ssh username@domain-name.local - if you are on the same network
or

ssh username@local-ip - same as above

or if you are connected to different networks:

ssh username@public-ip.

You can also setup password-less connection.
First, generate keys using ssh-keygen (you can leave everything default).

Then, copy your public key using
ssh-copy-id username@domainname.local (as above)

Repeat the process from the other machine.

Enjoy!


Why can't I unlock a KeepassXC file located on a NTFS volume mounted in Ubuntu?

To unlock a KeePassXC file stored on a mounted NTFS partition in Ubuntu:

Open Ubuntu Software app and find KeePassXC
Click on Permissions
Toggle "Read/write files on removable storage devices" to on


Why do I get a `failed to symbolic-link /boot/initrd.img' error when updating?

sudo rm /initrd.img (its only a symlink)

followed by sudo apt-get -f install linux-image-3.2.0-24-generic


First Unmount it:

sudo umount /media/(diskname)

Then mount it where you want:

mount -t auto /dev/cdrom /media/cdrom0

I think there is another (easier) solution to your problem: just make a symbolic link:

sudo mkdir /media/cdrom0

sudo ln -s /media/(diskname) /media/cdrom0


Wireless option missing in network settings

Make sure your wireless is enabled. Click the wrench icon on the right corner of the screen and see whether you can see the option wireless. If u can see then click on it and choose enable.


How to create Automated script in ubuntu using text editor

Search "unix cheat sheet" in google. You will get list of commands and its purpose.

There is something called as shell script in unix, similar to bat in windows. You can automate your work using shell script.

Use vim editor, it is a command line text editor.


What does a "No such file or directory” mean and How do I correct the problem?

In all Linux commands, a space is treated as a separator that separates command arguments. So if you try to do chmod +x first deploy.sh the command understands that you want to change permissions on two files: first and deploy.sh. I guess none of these files exists, so you get "No such file or directory" error.
Whenever you want to use a file name that contains spaces, you need to quote it, that is, enclose in either single or double quotes, like: chmod +x "first deploy.sh". You may also quote the space itself, preceding it with a backslash: chmod +x first\ deploy.sh.
Personally I would suggest avoiding filenames with spaces and changing the file name to first_deploy.sh - it will be easier to use. It's a common convention to use underscores in filenames that consist of multiple words.


Can I add a cron job without editing a file?

To install a crontab:

echo "1 1  * * *  test" | crontab -

should do the trick.

NOTICE that this substitutes the whole crontab. You have to save the value it had with crontab -l if you just want to add/edit things. For example

(crontab -l && echo "1 1  * * *  test") | crontab -

will add the line to your crontab.


I think the original problem was with the formatting of your time stamp.

The format is HH:MM:SS

I am not sure I am understanding your question about the order of the options. I do not think it matters as long as -i is followed by the input file name and -ss HH:MM:SS followed my -t HH:MM:SS

The -ss HH:MM:SS is the starting point, and -t HH:MM:SS is the duration

so -ss 00:01:00 -t 00:05:00 would start at the one minute mark and run for 5 minutes.

On my system, using ffmpeg, order does not matter (you can specify time or input file in any order so long as -ss is followed by the duration (-t) )


bash profile works for user but not sudo

When you run the script as sudo you are trying to access root. So your $HOME/.profile wont be accessed instead /root/.profile will be accessed.

So make the changes what ever you did in $HOME/.profile to /root/.profile. To create /root/.profile. Use the following commands.

sudo su
cd /root
touch .profile

after making the changes try running the script.

or edit $HOME/.bashrc and add the following line

alias sudo='sudo env PATH=$PATH $@'

Hope this helps.


Quoting a suggestion...

Your DDX does not work with your current kernel and/or libdrm. There are at least three possible reasons for this: the nouveau DRM kernel module is not loaded, a version mismatch between the Nouveau DRM and libdrm, or KMS being disabled.

First check, that lsmod command lists nouveau. If not, do modprobe nouveau to load the nouveau DRM kernel module, and check the kernel log for possible errors.

If the kernel module nouveau is loaded according to lsmod command, but there are no kernel messages about nouveau at all, then most likely Nouveau KMS is disabled. This prevents the driver to work at all. Possible places to disable KMS are:

kernel command line with: nomodeset, drm.modeset=0, nouveau.modeset=0 or similar
modprobe.conf or modprobe.d/ adding the module options drm modeset=0 or nouveau modeset=0
initramfs carrying the above module options
Check and remove all those that you may find, and retry.

Quote from http://nouveau.freedesktop.org/wiki/TroubleShooting/#index1h3


I'd use awk in paragraph mode (by unsetting the record separator):

$ awk -vRS= '/^(IP ADDRESS|MONTHS)/' test_file.txt
IP ADDRESS:
1. 172.17.17.17
2. 172.17.17.18
3. 172.17.17.19
MONTHS OF 2017:
01.  January   2017
02.  February  2017
03.  March     2017
04.  April     2017
05.  May       2017
06.  June      2017
07.  July      2017
08.  August    2017
09.  September 2017
10.  October   2017
11.  November  2017
12.  December  2017

Perl has the same functionality:

 perl -00 -ne 'print if /^IP ADDRESS/ or /^MONTHS/' test_file.txt


Laptop is bootting directly into Windows 8

There is a feature in Windows 8 that's called Secure Boot, this feature prevents any other operating systems booting on that system. This can be pretty annoying. To disable Secure Boot, you have to look within the settings of Windows 8. You can search Secure Boot online for more information.


You can always just create a /var/www/cgi-bin directory and put the scripts you want to run in there or even link it to /usr/lib/cgi-bin.  Beware though, this can create security issues since anyone who can access the web server can execute those scripts.


How to make the Wacom Bamboo Splash Pen CTL-471 work on Lucid Lynx 10.04?

This has to do with 10.04 LTS becoming an EOL release on May 9th, since the recent release of 13.04. Since the packages and everything were moved (/will be? I'm not exactly sure when this happens) to an archive, away from the normal server your terminal is trying to contact, the normal methods of updating/installing don't work.

So the only real suggestion we can give on this site (since we don't deal with EOLs) is: Upgrade to a supported version. The best method is to do a fresh install with a LiveUSB/CD, but upgrading should work as well.

See this article if you still really want to stay on 10.04 and install software.


How to checkout using subversion and https

You can specify a username using

svn co --username your_name https://svn.server.com/repository/trunk

and the password should be prompted afterwards.

However, it's not necessary to specify the username, svn is going to prompt you anyway.

This and more information can be found either in the documentation of svn or using a simple command:

svn help checkout


With two simultaneous users, how much memory is consumed?

There can't be really be any documentation for this as the memory usage depends on the running application (both open and those in background) and on your system (for example, desktop effects increase memory usage).

You'll find the memory increase by opening the system manager when you have one user logged in and then when you have two users logged in. Don't open any application when you do the test, that way other programs won't affect your test result.


gzip: stdout: No space left on device E: mkinitramfs failure cpio 141 gzip 1

I see you have some old kernels there, seemingly from a previous version of Ubuntu. I think that autoremove fails to act on kernels with a different major version number - at least I have seen cases before like that.

You also have a very small /boot partition. In the long term, or even now if it's an option, I would recommend you reinstall and not create a separate boot partition, or if you do make sure it is bigger. My experience is that the installer does not create one by default; on an UEFI system a small EFI system partition is created mounted on /boot/efi which doesn't interfere with the space in /boot where kernels are stored.

In the short term, you can make space by deleting the kernels yourself. You can remove all traces of the kernel by hand using the version string if APT cannot.

First check which kernel is running with the command

uname -r

it will output the version string, for example 4.4.0-34-generic

Do not delete that kernel

Choose one of the other versions you see in ls /boot; start with the oldest one 3.19.0-56-generic and find all the files that belong to it:

locate -b -e 3.19.0-56-generic

Now you can delete them using xargs

locate -b -e 3.19.0-56-generic | xargs -p sudo rm -r

You will see a list of files that will be deleted and you will be asked to confirm. If the list looks OK, type y and the files will be deleted.

Check that the files were removed:

sudo updatedb && locate -b -e 3.19.0-56-generic

Repeat this with the next oldest kernel. It is very much advisable to always keep a spare kernel, but I don't think those old kernels will be much use to you anyway, and your current kernel is presumably stable, so you can either continue until you only have only the currently running kernel version (indicated by uname -r) or only two kernel versions in /boot, then run

sudo update-grub
sudo apt update
sudo apt upgrade

And, fingers crossed, update-initramfs should be able to run OK. To maintain the situation, every time you get a new kernel, run

sudo apt autoremove


Ubuntu won't detect boot partition for Kali Linux

try up boot repair from this link:
https://help.ubuntu.com/community/Boot-Repair
and if didn t work try to see the report to know the the exact problem


Will Ubuntu 12.04 work with Intel-based 10 Gigabit adapters?

Yes, Ubuntu 12.04 will work just fine and includes built-in support for Intel 10 GbE controllers, which are used by your Supermicro AOC-STGN-i2S 10 Gigabit Ethernet PCI-E card.

Open-source drivers are in fact included with the Linux kernel, as ixgbe* modules, so you should never have to install drivers separately.


Nevermind. I looked through the code for GNOME, and apparently the lock-screen is written into gnome-shell, not just GDM. I feel like this is bad design, but who am I to tell them how to program?


Geforce GT240M: How to disable Notebook screen and enable external Monitor

Here is a simple script to turn off notebook display when external monitor is connected:

if xrandr -q | grep -q  "HDMI connected"; then
  xrandr --output LVDS --off --output DFP1
else
  xrandr --output VGA --off --output LVDS
fi

If you want to set a specific resolution, you may add "--mode 1680x1050" in the end of xrandr lines.
Output offset can be added using "--pos 100x0" command.

The script can be bound to any unused key combination or executed on startup using "System>>Preferences>>Startup Applications"

Note, that "DFP1" may be different on your system - check out 'xrandr -q' output with external monitor attached


If you are using Ubuntu >= 15.10, That command is left for compatibility reason only after moving to systemd. Use the below command instead:

systemctl list-units -t service

Reference: man systemctl


You need to manually modprobe br_netfilter to get this directory.

The following kernel commit separated this out :

commit 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f
Author: Pablo Neira Ayuso <pablo@netfilter.org>
Date:   Thu Sep 18 11:29:03 2014 +0200

    netfilter: bridge: move br_netfilter out of the core

$ git describe 34666d467cbf1e2e3c7bb15a63eccfb582cdd71f
v3.17-rc4-777-g34666d4

This is why 3.19 is different than 3.16.


How to find and replace word or character in paragraph using bash script?

Read the input of the user as follows:

#!/bin/bash

read input # creates a variable $input with the users input until <enter>

To replace a string in the paragraph:

echo $input| sed 's/search-string/replace-string/g'

To count the words:

echo $input| wc -w


Is there any reference or material about the preseed file of MaaS Fast Installer?

The fast installer does not use preseed at all.  It deploys a pre-installed image.  That is why it is faster.  I do not believe there is any way to do the customization you are looking for with the fast installer.

As for how to modify preseed files when using the default installer, you should be able to find what you need here: https://maas.ubuntu.com/docs/development/preseeds.html

Mark


Is there a GUI application to create Snaps?

When the phone/tablet images start moving to using snaps, the Ubuntu SDK will be the primary GUI for creating snaps.


TOS Violations
There are some programs and tools that exist to do this, but this is against YouTube's TOS.
Section 5.b :

Content is provided to you AS IS. You may access Content for your information and personal use solely as intended through the provided functionality of the Service and as permitted under these Terms of Service. You shall not download any Content unless you see a “download” or similar link displayed by YouTube on the Service for that Content. You shall not copy, reproduce, distribute, transmit, broadcast, display, sell, license, or otherwise exploit any Content for any other purposes without the prior written consent of YouTube or the respective licensors of the Content. YouTube and its licensors reserve all rights not expressly granted in and to the Service and the Content.

This basically means that unless explicitly stated otherwise, you may not download any content posted on YouTube.
Obviously, basically nobody follows this, but I do feel like I am obligated to inform you that this is, in fact, against their Terms Of Service.

Actual solution
Now that you've been informed of the TOS issues presented when doing this, there is a program that does download YouTube videos. This program is called youtube-dl.
To install it, run
sudo apt-get install youtube-dl

To use it, the syntax looks like
youtube-dl (YouTube-Video-Link)

For example
youtube-dl https://www.youtube.com/watch?v=dQw4w9WgXcQ

Here's the official documentation.


While installing Ubuntu on a Mac, should I install it under EFI or BIOS?

Most of the installation process is identical for EFI-mode versus BIOS-mode installations. They differ in three ways:

When booting the installer in BIOS mode, you can boot either 32- or 64-bit versions of Ubuntu, at least if you've got a 64-bit CPU. In EFI mode, you can install only 64-bit versions of Ubuntu, and that only if you've got a 64-bit EFI (which most Macs do). If you have a rare Mac with a 32-bit EFI, things get complicated.
If you install in EFI mode, the installer will set your EFI System Partition (ESP) to be mounted automatically at /boot/efi. If you install in BIOS mode, this won't happen. This detail can be changed manually after installation.
The installer will install a boot loader to match its own boot mode. (An exception is if you launch into "try before installing" mode, open a Terminal, and type synaptic -b. In this case, no boot loader will be installed.)

IMO, installing a 32-bit OS on a 64-bit CPU seldom makes sense these days. One notable exception is some fairly early Intel-based Macs, which have 32-bit EFIs. Thus, the first point is unimportant for most users. As noted earlier, an exception is if you've got one of the rare Macs with a 32-bit EFI (from roughly the first year of Intel-based Mac production).

The second point is easy to change, and so doesn't bear much consideration, provided you understand how to edit /etc/fstab. If you don't understand this topic, see this page.

The boot loader issue is the big one. To launch a BIOS-mode boot loader, Macs require that your disk use an MBR partition table or a GPT with a hybrid MBR. OS X is normally installed to GPT, which means that if you're dual-booting, you'll need a hybrid MBR to dual-boot with a BIOS-mode boot loader. Please read the link earlier in this paragraph. It describes hybrid MBRs in more detail, including why they're so DANGEROUS. For this reason alone, I strongly advise against using a BIOS-mode install of Ubuntu if you're dual-booting with OS X.

If Ubuntu is to be the only OS on the computer, though, you can use a straight-up MBR (with no GPT) and install in BIOS mode. This is likely to work better than an EFI-mode installation, but it will limit your options if you subsequently decide you want to dual-boot after all. It will also make it harder to update the computer's firmware, should that ever be necessary.

Getting back to dual-booting, if you install Ubuntu directly in EFI mode, it will try to install an EFI-mode version of GRUB. This may work fine, and may enable you to dual-boot with OS X by using GRUB's boot menu. This configuration will bypass rEFInd (unless you re-install it). I've seen reports of this configuration not working, though; the system will boot straight to either OS X or Ubuntu, making it difficult to boot the other OS.

If you want to keep using rEFInd, the safest approach is:

Launch the Ubuntu installer in its "try before installing" mode. It doesn't matter if you do this in BIOS mode or in EFI mode, except for the comment about whether your ESP will be mounted automatically when you're done.
Open a Terminal window.
Type ubiquity -b. This will launch the Ubuntu installer. The -b option tells it to not install GRUB.
Install Ubuntu regularly. Be sure to use ext4fs, not another filesystem. (If you really want to use another filesystem, you can, but that complicates matters slightly. Post back with details if you need further advice on this point.)
When you're done, reboot. rEFInd should appear (if it's already installed) or the computer will boot straight to OS X (if rEFInd is not already installed).
In OS X, (re-)install rEFInd. This step exists solely to ensure that the EFI filesystem driver for ext4fs is installed. You could instead install that driver manually yourself. (You could also manually install another EFI filesystem driver, if that was necessary.)

The result of this procedure is that, when you reboot, rEFInd should come up and give you the option of booting either OS X or Ubuntu. One caveat is that the Ubuntu option will require some tweaking if you use a separate /boot partition. You can boot on a one-time basis by hitting F2 or Insert twice, rather than Enter, once the Ubuntu option is selected. You can then add ro root=/dev/whatever, where /dev/whatever identifies your root (/) filesystem. Once you've booted Ubuntu, run the mkrlconf script that comes with rEFInd. This will generate a file called /boot/refind_linux.conf, which will obviate the need to make these changes.


I am testing the new Opera 11, but it keeps telling me I need to install flash player

Opera will grab the plugin from /usr/lib/flashplugin-installer/libflashplayer.so, which is the default location for the flash shared object installed by flashplugin-installer package. So make sure you have both.

If you don't have them, then install the package with:

sudo apt-get install flashplugin-installer

If you have flashplugin-installer package and the file mentioned above, but it still doesn't work, then you could try to copy the plugin shared object to ~/.opera/plugins with the following command:

cp /usr/lib/flashplugin-installer/libflashplayer.so ~/.opera/plugins/libflashplayer.so

Also check if you don't have any old version being detected by Opera and disable it. You can do that from opera:plugins page.

For other video types you will need gecko-mediaplayer, which is the only media plugin that works with Opera.

sudo apt-get gecko-mediaplayer


Not able to change the Nvidia driver in ubuntu 20.04

This problem should be fixed by running
sudo ubuntu-drivers autoinstall

after a reboot.


An easier way would be to use a file-manager like nautilus or thunar.

Hit Ctrl+L and use

  smb://user@name/images

and type in the password when prompted.


Enabling serial network devices with ModemManager

In the source code, the first check for ID_MM_CANDIDATE is done on the port (i.e. /dev/ttyO4). After this, ModemManager will retrieve the physical platform device (the serial port itself) which we can see is /devices/ocp.3/481a800.serial, and then check this for the ID_MM_PLATFORM_DRIVER_PROBE flag.
If instead the udev rule is changed to
ACTION=="add", KERNEL=="481a800.serial", ENV{ID_MM_DEVICE_PROCESS}="1"

then ModemManager will correctly see the flag on the parent device (note: ID_MM_PLATFORM_DRIVER_PROBE doesn't exist anymore).
# udevadm info /sys/devices/ocp.3/481a8000.serial
P: /devices/ocp.3/481a8000.serial
E: DEVPATH=/devices/ocp.3/481a8000.serial
E: DRIVER=omap_uart
E: ID_MM_PLATFORM_DRIVER_PROBE=1
E: MODALIAS=of:NserialT<NULL>Cti,omap3-uart
E: OF_COMPATIBLE_0=ti,omap3-uart
E: OF_COMPATIBLE_N=1
E: OF_FULLNAME=/ocp/serial@481a8000
E: OF_NAME=serial
E: SUBSYSTEM=platform
E: USEC_INITIALIZED=990701

The device now appears in mmcli -L and nmcli device status.


Dpkg broken pipe error when using os.popen in Python

The dpkg --get-selections call works alright; the problem is in the following line 24 where you try to open a file with empty file name:

with open("", "w") as f:

Empty file names are not allowed. Use a "real" file name, or a temporary file of you don't want to care about names and location:

import tempfile
with tempfile.TemporaryFile() as f:

Furthermore, file has no function writeline, you're probably looking for writelines.

f.writelines(dpkg_output)


How do I remove installed packages (and everything related to them) in Ubuntu Studio 20.10 using console?

The comment from Charles Green helped solve the nvidia drivers removal.
All uninstalled now with this one command line in console:
sudo apt remove --purge ~nnvidia
Charles just told me the double n is nvidia specific. Still awaiting answer about the ~, will edit when I have it.


Sharing server to several computers at home

To use your server's computing power on the old machines, log on from the old machine using "ssh -X" from a terminal and execute the program. That will forward the X output to your old machine using the local X-server while using your server to do the computations. You can of course write scripts to execute often used programs. And to avoid typing your password all the time, you should add your public ssh keys to the servers known_hosts. That should work fine for browsing the web, etc.

Heavy multimedia stuff and playing 3D games doing this will most probably still not be too much fun and not guaranteed to be lag-free (quite the contrary, actually) and forwarding sound is not even included, yet.
For watching video or listening to music, you could set up streaming servers on your server and then connect from your old client machines, but that will still use your old machines computational power to decompress the (mpeg-)stream.

Anyway, to use more of your server's hardware I'd then go on exporting the home directory on the server using NFS and mount them on your old machines. And then continue by using nis/yp to synchronize the accounts over all of your machines.

I promise, that will be exciting, but for your requirements, maybe buying a couple of SSDs and some more RAM for your old machines will do the trick better.

So, this is not really a solution to your requirements, but maybe gives you some ideas where to look further or maybe to adjust your requirements and change the setup of your systems. For example, I'd highly recommend to do heavy multimedia stuff and playing 3d games directly on the server, while using the old machines for browsing the web, remote controlling the server, playing music and especially non-multimedia applications.

Cheers


Kubuntu 12.04 keyboard + mouse do not respond

I had the same problem and managed to fix it by reinstalling the OS (64-bit), but this time without installing third party software and downloading updates. I then installed the the graphics driver (NVIDIA) under Systems and Muon to update the system.


Error message with scrambled letters: is this a bug?

The text is not scrambled, but some characters in it are not able to display. It should say: System program problem detected.

Apport detects crashes and writes reports to /var/crash. update-notifier watches that directory for changes. When it sees a new report, it puts up the dialog that you saw.

See anatomy of a crash for more information.

I don't know how long it takes for a crash to be detected, so it's hard to know what caused the crash. But you can view the crash reports in /var/crash.

The question remains as to why the message can't display properly. You are apparently running your system in English and all of the characters would have the same encoding in ascii and unicode. The primary text ("System program...") is displaying in bold. It makes me wonder if perhaps the bold version of that font is corrupted.

Edit: No applications available to open rapport_utast.tex. Again the problem is with the bold version of the system font.

Try re-installing ttf-ubuntu-font-family and then rebooting.

To re-install use Synaptic  or run in a terminal:

sudo apt-get --reinstall install ttf-ubuntu-font-family


Nautilus doesn' allow thumbnail for image size above 4096 KiB

No workaround found, upgrading to Ubuntu 19.04 solved the issue.
I successfully tested 8MiB and 10MiB thumbnail size limit using Nautilus preference pane.


In ubuntu 12.04, any changes made manually to /etc/resolv.conf will be overwritten later by a DNS information manager called resolvconf.

If you want to change the default settings, you could modify files base, head, or tail under /etc/resolvconf/resolv.conf.d.

base: Used when no other data can be found
head: Header of default resolv.conf. The server inside will the first
ones to check.
tail: entries appended at the end of resolv.conf. In
some cases, upgrading from a previous Ubuntu release, will make tail
a symlink to original

Ref:

Auto DNS resolving in Ubuntu 12.04 desktop


98% of the time they're part of the kernel package. Only if those don't work (or don't suffice) do you need to worry about getting external drivers.


You have to install 'guest additions'. Navigate to menu, under Devices choose Install Guest Additions, enter your password, wait for the script to completed, reboot your virtual machine.


Ubuntu doesn't recognise my external monitor

I'm an owner of a Dell XPS 15 laptop (L501X to be precise). It comes with a Nvidia GeForce 420M (or later) graphics card, so if you have the NVidia drivers installed & activated, try the NVidia X Server Settings program to detect your new display.

Type nvidia in the dash to find it. Then click on Detect Displays in the X Server Display Configuration menu. See:

Hope this helps!


How can I prevent specific updates from appearing in Update Manager's list of updates in Ubuntu 12.04?

Use the terminal command sudo apt-get install {specific-package} to update only {specific-package} and the packages which it depends on.


Probably you edited the wrong file. I have a feeling that you are supposed to add that line to e.g. /etc/lightdm/lightdm.conf, which should (at least) contain:

[SeatDefaults]
greeter-setup-script=/usr/bin/numlockx on

Optionally you can use a dedicated file, e.g. /etc/lightdm/lightdm.conf.d/numlock.conf, with the same contents.


Making a Bash script to set desktop wallpaper as animated gif -- what do these errors mean?

The first three errors are because you have non-ASCII ‘ (and ’) characters in your script - you need to replace them with regular single quotes '

The fourth is likely because your shebang #!/bin/sh is invoking the dash interpreter, not bash: see DashAsBinSh


Uniformizing Unity icon background color

Open the "CompizConfig Settings Manager" application
Select the "Ubuntu Unity Plugin"
On the "Experimental" tab, you can adjust the backlight mode.  Based on your question, you want "Always Off"

If you don't have CompizConfig installed you can install it via this question:
Where is ccsm found on my application menu?


Can I install Windows after installing Ubuntu on UEFI?

To install Windows alongside Ubuntu, you just do the following:

Insert Windows 10 USB
Create a partition/volume on the drive to install Windows 10 on alongside Ubuntu (it'll create more than one partition, that's normal; also make sure you have space for Windows 10 on your drive, you might need to shrink Ubuntu)
Install the Windows 10.

That's it!

Note: when making sure things are ready for your dual boot, check if Ubuntu is installed in the GPT partition table! While 99% of the time you will be using GPT if you're planning to do this, it is possible to install Ubuntu's UEFI on MBR but Windows 10 does not support that strange use-case. In that situation, convert to GPT if possible. If not, backup and reinstall, and I'd recommend that as it'll be easier.


Need help installing/updating graphics card

You can try going to System Settings > Software & updates > Additional Drives. You can change the graphics driver there. Try another one or updating the actual one.
If it doesn't help, I'm not sure if the problem would be on the graphics card (since it worked fine for a few days)


Cannot login to cockpit after upgrading to focal fossa

If your favorite login shell is tcsh (or csh), the workaround is to create a new user that uses bash for its login shell and belongs to group sudo.


View text in terminal with specific patterns highlighted

Actually, this can be done very easily with some grep parameters.

The magic command you are looking for is:

grep --color -E "test|$" yourfile

Here's some sample output:

Full disclosure: That command was taken from this answer.


Frequently network down even after being conneted to WIFI

You can fix it by upgrading the kernel to 4.10.

Run

sudo apt install linux-generic-hwe-16.04

and reboot.


How to separate a given type of file from others?


WITHOUT INTERNET

You can install it using

sudo dpkg -i /path/to/deb/file

followed by

sudo apt-get install -f

WITH INTERNET ACCESS

install Gdebi

in terminal enter

sudo apt-get install gdebi

after install completes go to the .deb file in file explorer-->right click-->open with--->select gdebi--->once gdebi opens and loads select "install package"


How to login to console session In xrdp?

Ubuntu 18.04 and xrdp packages are not using vnc backend component by default. xRDP package is using the xorgxrdp package nowadays...

So, the first thing I would do is check if you have any vnc server up and running on your target machine. Then I would also ensure that the vnc server start at boot time.  When these conditions are met, I would assume that you can peform your console connection through vnc....

Please note that there might be some limitations in the way vnc works on Ubuntu 18.04..
Please note also that xRDP can be a good replacement for vnc if you simply need to perform remote session on Ubuntu machines. Some limitation do exists as no way to connect to the console + the same user can only be connected either locally or remotely, not on both at the same time

Hope this help

the following links might be useful....

Ubuntu 17.10 & 18.04 – Configure x11vnc to boot at startup
XRDP – How to connect to console or how to connect to Unity Desktop


My guess would be that the account you're changing to doesn't allow logins. If you have access from the nuri account, list the users in /etc/passwd and look for the login shell that deneme2 is using.

grep ^deneme2: /etc/passwd

It should end with something like /bin/bash. I'm guessing it says /bin/false or something similar.  If you have admin access you can change the shell with the passwd command. I'm guessing, though, that you don't if this is the case. You'll need to talk to the system administrator.


My StarCraft on wine 1.5.24 is on all workspaces

Found a problem. Stupid simple.
This solved my issue:

Go to PlayOnLinux
pick an app and click on configure button
pick a "Graphics" tab
make sure that "Allow the window manager to...* checkboxes are selected

And than again click to play a game, now it is working on one workspace only. Yey!


That unknown partition is the windows system reserved created by the Windows 7 or 8 when doing their respective installation. It is approximately 128 MB for system reserved stuff, which includes part of the installation process and booting. You do not want to delete that partition except if you want to remove Windows completely.

The flag shown in the image (msftres or Microsoft Reserved) can be found in Is it safe to format msftres, msftdata and hidden partitions?

If you go into Windows you will not see this partition on it since it is marked with a special flag that tells the Disk manager (In Windows) not to see it). With Ubuntu using any partition manager can see it. I recommend not moving the partition, resizing it, deleting it or doing any changes to it unless you want to have some Windows issues.


Cannot access windows 7 NTFS /users/USERNAME all other directories are ok

This is indeed an issue of ownership. The C:\users\NAME directory is equivalent to the home directory and can only be accessed through elevated permissions.

You should avoid using nautilus to access the data on this, but rather first attempt chown on the user directory to remap it to your user's ownership. Once done, it should be possible to retrieve the data.

Note that this may corrupt access to the directory from windows-side, or corrupt the Windows user itself. Given that this hard drive seems less-than-workable, however, I doubt that you plan on using it again without formatting it, so this should be possible without any problems.

If it does not solve the issue, however, please give the output of ls -l on the users\NAME directory.

(I hope this doesn't come too late for you)


Thunderbird does not open when I use "send link" in Firefox 12.0

This is a regression that will be addressed shortly.  You can track this issue here.


Found it:

In PlayOnLinux, right click the program, click "Configure Wine", move to the graphics tab and deselect "Allow window manager to decorate the windows"


New Motherboard, Atheros AR8161 not recognised. How to install drivers?

I think the driver should be in package linux-backports-modules-cw-*  where the * the the kernel which you can get from running

uname -r

Download the package on a computer with internet connectivity, put the .deb file onto a usb or cdrom, and read it on your new computer, so you can install it directly.


Disk un mounting after write operations on samba

Thanks for the help, After several hours I've found a solution. Here are the 3 lines you have to add in samba configuration.

  use sendfile = no
  large readwrite = no
  max xmit = 16644

Source: gentoo forum


Unable to change brightness using after root access

The normal output redirection operator is always executed with your user privileges, also when you write a sudo in front of the command which generates the STDOUT text. In other words, this will fail if you dont have the permission to write to that file

So sudo echo won't work even when you are using sudo,

you should use tee in this scenario like below

echo 200 | sudo tee /sys/class/backlight/intel_backlight/brightness


How to change "Keyboard Input Method System" to "None" in Ubuntu GNOME?

You can use im-config to change this. My system wil laccept ibus or xim. The latter reports as "none" in the GUI.

im-config -n ibus
im-config -n xim


I suggest that you should install two version of Perl side by side, because the default 5.10 is a critical part of the system itself, packages are depend on it, a big upgrade to it is not a good idea.

If you want to install Perl 5.16.1 from Larry, you could get the tarball from http://www.perl.org/get.html . Extract it, you could find a file named "INSTALL" which include installation steps. Basically, sh Configure make make test make install

If you want ActivePerl 5.14.2 , you could get it from: http://www.activestate.com/activeperl/downloads . Extract it, and sh install.sh .

Beware to set the install directory to some place in which you have write permission and not to replace the system's 5.10.


Clementine refuses to play m4a, wma and wav

Your issues seem to go beyond codec install as clementine should play wav without anything.

In any event clementine uses gstreamer0.10 so make sure that these are installed:

gstreamer0.10-plugins-bad
gstreamer0.10-ffmpeg

(don't think the gstreamer0.10-plugins-ugly is needed but you could install it)

If there is still an issue then try deleting the .bin file inside ~/.gstreamer-0.10/

Note that gstreamer0.10-ffmpeg is not available in 14.04 but can be had here:
https://launchpad.net/~mc3man/+archive/ubuntu/gstffmpeg-keep


The boot loader could be either an EFI-mode boot loader on the EFI System Partition (ESP) or a BIOS-mode boot loader in the MBR or on a Linux partition (although if you've deleted all of the Linux partitions, a partition is an unlikely location). You can check for and deal with these possibilities as follows:

You can mount the ESP in OS X by typing sudo mkdir /Volumes/ESP; sudo mount -t msdos /dev/disk0s1 /Volumes/ESP. (This assumes the ESP is the first partition on your disk, as it is by default. If it's elsewhere, you'll need to adjust the command appropriately.) You can then search for a Linux boot loader under /Volumes/ESP. It would probably be in /Volumes/ESP/EFI/ubuntu. Delete the boot loader (a .efi file), and optionally its entire directory.
You can erase the part of the MBR (or partition) that holds the BIOS boot code using dd. This is safest to do from Linux, so I recommend you boot a Linux live CD, then type sudo dd if=/dev/zero of=/dev/sda bs=440 count=1. Be very careful with this command! A mistake in the parameters can cause you to trash the disk. OS X is less suitable for this because, IIRC, it's impossible to write part of a sector with OS X's dd, and it's critical that you wipe just the first 440 bytes of the sector. (Sectors are normally 512 bytes in size.)

Alternatively, and a bit safer than the second option, you could upgrade from the abandoned rEFIt to its currently-maintained fork, rEFInd. You can then edit its refind.conf file to achieve your ends. You can exclude directories from scans for EFI boot loaders with the dont_scan_dirs line, or remove all BIOS-mode boot loaders with the scanfor line (omit the hdbios option). The drawback to excluding BIOS-mode boot loaders with rEFInd is that if you're dual-booting with Windows, you'll probably lose the ability to boot it.


As you've observed, not all shells support brace expansion.

Way 1: Two separate paths (i.e., writing the prefix twice)

If your goal is really just to do it in one command, a simple way is:

cp directory/file1 directory/file2 destination

The cp command supports multiple source arguments followed by a destination argument. In fact, that's what's happening with the command that works for you in Bash. Bash performs brace expansion, which converts the command you've been using into the one shown above. That is, when you run cp directory/{file1,file2} destination in Bash, the cp command never sees any curly braces.

A command like that is simple and easy to understand. I suggest considering it.

Way 2: A variable for the prefix

But if your goal is to avoid repeating yourself, then you might prefer not to do it that way, especially if directory is actually a long path. After all, if you have to edit the path later in the script, you'd have to make changes to both occurrences.

You can store directory (or whatever, presumably longer path that is) in a shell variable:

dir='directory'
cp "$dir/file1" "$dir/file2" destination

$dir is parameter expansion. The shell replaces it with the value held in the variable dir. When using parameter expansion, you should not omit the double quotes--except in the rare case that you want field splitting and globbing to be performed. (This applies to Bash as well.)

That's two commands, but if your actual goal is to avoid repeating yourself, that may be what you want. You could write

dir='directory'; cp "$dir/file1" "$dir/file2" destination

to make it "one command," but that's no shorter and it's a bit less readable.

(Note that you cannot simply remove the ; there. The result of doing would be a well-formed command, but it would not do what you want. It would run the cp command, passing an an environment variable called dir with the value directory into the cp command's environment. Since it is the shell and not the cp command, that expands dir, this would not work.)

Way 3: cdig to the prefix

If your script isn't doing anything else after performing this operation, or it doesn't matter what the current directory is for subsequent commands, then if destination is an absolute path, you can use:

cd directory
cp file1 file2 destination

But I don't recommend that for scripting unless your script performs subsequent actions that benefit from being run from that directory, or can be more tersely or simply written when they are run from that directory. Except when the directory a script is run from is meaningful to the purpose of the script, relying on it can make the script harder to reason about; furthermore, if the cd command succeeds but the cp command fails, the resulting error messages may be less than fully illuminating. Instead, I mention the technique of cding to the source directory because it is a useful pattern for interactive shell use.

(As Hannu pointed out, you can enclose any number of commands together inside ( ) to run them in a subshell, and changes to the shell environment, including the effect of cd, will not persist after the command has run. This is a widely useful technique, and it was a substantial omission that I had not mentioned it. Note, however, that this does not mitigate any problems relating to having a relative path for destination.)

Note that if the cd command fails, the other commands will still typically run. This could copy different files you don't want copied (if there are other files with the same names in the directory the script was running from) or producing confusing error messages. So you may prefer:

cd directory && cp file1 file2 destination

The && causes the second command to run only if the first command succeeded. Note that that still does not undo the effect of running the first command. After the whole thing runs, you'll still be in directory, unless you ran it in a subshell with ( ).


Yes, there is an amazing GUI called conkey-manager. You can use it to configure conky, manage themes, etc.

Install it by adding the PPA:

sudo apt-add-repository ppa:teejee2008/ppa
sudo apt-get update
sudo apt-get install conky-manager

Then just run conky-manager.


Can't access home directory during boot. Any solutions?

Yes. Your home won't decrypt and mount until you log in.

You want to move this script to start when you log in.


How to replace my username in a script with variable

You can use the variable $HOME for the home, and $USER for the user.

Your example can then be $HOME/Downloads or /home/$USER/Downloads.


How can I check if a package is installed (no superuser privileges)?


Delete all files having extension '.sh' but keep one file matching the extension by terminal

You can use -not:

find . -maxdepth 1 -type f -name '*.sh' -not -name cron.sh -delete

Also, GNU find has the -delete option which is simpler to use and than rm -rf.

Important: Always put -delete at the end. As explained in man find:

  Warnings:  Don't  forget that the find command line is evaluated
                as an expression, so putting -delete first will make find try to
                delete everything below the starting points you specified.

Alternatively, you could use a shell loop (but don't, the find command above is far more efficient):

for f in *.sh; do [ "$f" = "cron.sh" ] || rm "$f"; done


What are the alternatives to Camtasia Studio to edit videos on Ubuntu?

I would recommend the program "Openshot". Install it from the Softwarecenter. It is quite good for 1 and 4. Point 3, I don't know. Point 2, there is a title function in Openshot. Or alternatively, there are different subtitle tools, as gnome-subtitles, which could do the job.


The consumer_sync.ldif you use try to add attributes even added in your directory, now you have to write the LDIF file that modify them. Don't know if it's possible, but perhaps you can try to modify config with Apache Directory Studio.

You must adapt this, it's just given "as is" without test.

# syncrepl specific indices
dn: olcDatabase={1}hdb,cn=config
changetype: modify
replace: olcSyncRepl
olcSyncRepl: rid=0
 provider=ldap://Your new adress
 bindmethod=simple
 binddn= The Bind DN
 credentials= Your secret
 searchbase="dc=...,dc=..."
 logbase="cn=accesslog"
 logfilter="(&(objectClass=auditWriteObject)(reqResult=0))"
 schemachecking=on
 type=refreshAndPersist
 retry="60 +"
 syncdata=accesslog
-
replace: olcUpdateRef
olcUpdateRef: ldap://Your new adress
-


My Samba server isn't showing up in windows

The google ranking of this answer is high, so I thought I'd contribute the current Windows 10 solution.
Windows 10 no longer supports NetBIOS discovery.

You can fix this by enabling the insecure SMBv1 (or so I've read), but that's a bad idea and you have to do it on all your clients. The best way is to implement Web Service Discovery on your Linux server.

wsdd accomplishes this. Pre-made service files are available from the guy's git also (although for Ubuntu I had to change the group from nobody to nogroup to get it to work). It works great.


Online Accounts Hang after fresh install

Well, I think I fixed my problem by re-booting my cable modem/wifi.  It didn't seem like it could be the problem since I was able to access the internet for other activities such as accessing this web page, watching youtube videos, etc.  However, since some other person mentioned that going from a wifi connection to a hard-wired connection on his computer fixed his problem, I thought it might still be something to do with my internet access.  Actually, I think it was more likely something to do with the router.  Anyway, thank you to anyone that read my question and gave it some thought.  Perhaps someone else will run up against this and my solution might help.


In file /etc/default/grub, add nomodeset to the line

GRUB_CMDLINE_LINUX="XXX"

becomes

GRUB_CMDLINE_LINUX="XXXnomodeset"

Then run

sudo update-grub.

Then restart.


Installing Ubuntu 12.04 or 12.10 inside VMWare

This now works for me in 12.10. First I configured my corporate firewall to let VMware Workstation get through when I was prompted for my credentials. Today I updated to 8.0.4 build-744019. I created a new VM and the install completed in about 15 minutes, including VMware Tools. For 12.04 try again either outside your firewall or with your firewall configured before you start the install. And use 8.0.4 build-744019 or newer.


How do I fully install Ubuntu on a USB Flash Drive?

It will work, but it will be damn slow. Better make a live USB drive with space reserved to save your settings. Every Ubuntu distro can do that through usb-creator-gtk.

If you choose full install instead than plug your USB stick in, and start a normal install. When reaching the HDD selection, select your USB stick, and go forward.


How to change screen resolution when installing Ubuntu 16.04

When installing Ubuntu at times depending on your system the installation window might not be seen clearly. This can't be changed during installation so simply use your cursor to move the installation window to the left of your screen so you can see the buttons.

With this this I believe you should be able to access and accept all that is required to get the installation to the end.


IPv4 Address Sharing Issue? Trying to map IPv4 address from host OS to BT5 VM

Instead of NAT, use bridge adapter. If your Host (Win) is getting IP through DHCP then your vm (bt) will also get IP through the same source.

Hope it helps.


stop avahi-daemon - to stop the service

cd /etc/init ; touch avahi-daemon.override ; echo "manual" > avahi-daemon.override - to prevent it from initiating on reboot .


How to establish a default gateway in Ubuntu 14.04?

Check your current automatic settings with ifconfig. If the gateway hasn't been automatically set, you can do it manually by editing /etc/network/interfaces. Something like;

auto eth0
iface eth0 inet static
    address 192.168.1.2
    netmask 255.255.255.0
    gateway 192.168.1.1


ubuntu 18.04 tourn off the screen but dosn't shutting down since the last update

with ryzen , also your screen might fail or system goes to wrong cstate, this can be a funny search

see Gentoo WIKI for specific command lines and sleep modes to prevent
the system might still react to the Magic SysRQ combination when the graphic freezes .. suggested order:

u (Umount)

s (Sync)

b (reBoot)

there is a "similar" thread here where switching away from gnome is suggested:
https://unix.stackexchange.com/questions/517543/ubuntu-18-04-amd-ryzen-why-random-freeze


Xerox WorkCentre 6015B - Requires authentication / Credentials required in order to print

I’ve had this same issue with Pop!_OS (an Ubuntu-based distro) after upgrading to 19.10. At my workplace we print via a print queue with two printers. When I configured the printer in Pop!_OS 18.04 I remember that I needed to enter a username/password set up by the IT team only once. After updating to 19.10 I see this notification appear but that takes me to the print queue where I could do nothing, which seems to be the same problem.

To solve it I stopped CUPS:
sudo service cups stop

And then edited the file /etc/cups/printers.conf (you’ll need root access). Look for your printer (usually the <DefaultPrinter ...> block) and look for the line that starts with AuthInfoRequired. In my case it was AuthInfoRequired none and I changed it to AuthInfoRequired username,password.

After that I restarted CUPS:
sudo service cups start

And after sending a job to the printer, I had this printer authentication dialogue window show up. I entered the username/password, clicked on “Remember password” and this fixed it for me.

I hope that helps.

Also, it might be worth comparing to the previous configuration files, I think they are kept in /etc/cups with a .0 extension. Unfortunately I had already messed with them and I lost the original ones. I suspect that the issue must be there.


There were multiple annoying faults with the desktops for all versions. I suppose they were caused by alterations.

The problems were solved by reinstalling Ubuntu.


The problem is that the netflix app uses certificate pinning.

"Certificate Pinning is where you ignore that whole thing, and say trust this certificate only or perhaps trust only certificates signed by this certificate."
https://security.stackexchange.com/questions/29988/what-is-certificate-pinning

I would recommend you upgrade to Squid 3.17 because you likely will want to use tranparent mode because there is no way on the ipad to configure the netflix app to connect to other ports. 3.17 now allows peek and splice in transparent mode

"Our goal is to allow our users to browse some important web pages (like banking or payments systems) without SSL interception (it's called Splice in Squid's terminology) but the rest of HTTPS traffic should be intercepted ("bumped") in order to verify the content."
"Now thanks to the TLS extension in HTTPS standard (introducing SNI) and Squid's peek & splice feature it's possible to determine server_name by peeking at client's request (as long as the client is TLS/SNI compatible)."

http://marek.helion.pl/install/squid.html  <--awesome, thank you Marek!

This is what I ended up doing

acl step1 at_step SslBump1
acl step2 at_step SslBump2
acl nobumpSites ssl::server_name .netflix.com

# Peek at client's TLS-request in order to find the SNI
ssl_bump peek step1 all
# don't bump the nobumpSites
ssl_bump splice step2 nobumpSites

# bumping all other SSL connections
ssl_bump bump

If you don't know what the SNI should be (.netflix.com) use wireshark to look at the client hello.  Because the netflix client traffic is https the only way for squid to know what the domain is to peek at the unencrypted client hello that should contain the SNI.

I should note it takes the ipad netflix app about 60 seconds to start playing the video.  I have an idea why and will update here later.

Important note (not implemented above)
"Can squid mitm SSL connections, but deliberately generate invalid certs for upstream connections which are self signed or invalid so my browser will flag them?"
"The current Squid do that provided you do the SSL-Bump "bump" action at
step3 when the server details are known."
http://lists.squid-cache.org/pipermail/squid-users/2016-March/009707.html
<--Big thanks to Amos for all the squid knowledge he shares!

Other sources
http://www.squid-cache.org/Doc/config/acl/

http://lists.squid-cache.org/pipermail/squid-users/2016-April/010009.html


'System testing' app doesn't work in Ubuntu 13.04

Try the following:

Kill all running instances of checkbox-qt: pkill checkbox-qt. Please note that a python process is also started, you have to kill that too:

$ ps fax | grep check
3796 pts/3    S+     0:00      \_ grep --color=auto check
3761 ?        Sl     0:00 python3 /usr/share/checkbox/run /usr/share/checkbox/config/checkbox-qt.ini

Start checkbox-qt from a terminal window. (By opening a terminal window and typing: checkbox-qt.)
Note the following output:

$ checkbox-qt
SYSTEM TESTING: Please enter your password. Some tests require root access to run
properly. Your password will never be stored and will never be submitted with test
results. PASSWORD:

Enter your password at the terminal and the test should continue.


Ubuntu server remote desktop blank screen

I issued

echo "lxsession -s LXDE -e LXDE" >~/.xsession

and it was back in business also with RDP


Apache2 installation problem in ubuntu 14.04 Lts

First it sound like some things didnt get removed like they should have.
Press Ctrl + Alt + T to open a Terminal.  At which point you will type in the following

sudo apt-get purge apache2

This removes all files with this package including the config files.  At which point you can reinstall the files.


I tried to create an AppImage from deb files with pkg2appimage.

amarok.yml

app: Amarok
ingredients:
  dist: disco
  packages:
    - amarok
  sources:
    - deb http://archive.ubuntu.com/ubuntu/ disco main universe
    - deb http://archive.ubuntu.com/ubuntu/ bionic main universe

Then run bash -ex ./pkg2appimage amarok.yml (with https://github.com/AppImage/pkg2appimage/blob/master/pkg2appimage)

The result is an AppImage that runs on a system with Amarok installed but not if not installed (native).

My solution for now is to add the bionic tls sources again and install amarok from there. This is not a very clean solution but the simplest for now.

Add to /etc/apt/sources.list:

deb http://archive.ubuntu.com/ubuntu/ bionic main universe
deb-src http://archive.ubuntu.com/ubuntu/ bionic main universe

Then run apt-get update and apt-get install amarok.


Can I open two or more files in vim at once?

You can open a different file in vim with the :o command, like so:
:o /file/To/Open

This closes your current file and opens /file/To/Open.
As of vim 7.0 you can use the tabs feature to open multiple files at once.  Use vim's :tabnew command to open a new tab:
:tabnew [filename]

Where [filename] is an optional file to open in the new tab.
To switch between tabs use any of the following commands:

:tabn - switches to the next tab.

:tabp - switches to the previous tab.

gt - toggles through all tabs, from left to right.

gT - similar to gt but in opposite direction.

:tabfirst - switches to the first tab.

:tablast - switches to the last tab.

You can also pass multiple files to vim and have it open them in different tabs like so:
vim -p file1 file2 etc

To close a tab, use the :tabclose command.
For more tab related info see Vim tips: using tabs on Linux.com.


14 LTS, /usr/bin suid flags, looking for an offical developer

Instead of asking a dev for a list of package, maybe you can ask your system to restore the permissions of installed packages to their original state ?

To get a list of installed packages, you can use the following command :

dpkg --get-selections | grep "install" | grep -v "deinstall"

you can then use apt-get install --reinstall <package>, which will reset the package's files permissions.

If you want to do that for all your packages in one command, you can try:

sudo apt-get install --reinstall $(dpkg --get-selections | grep "install" | grep -v "deinstall" | cut -f1 | xargs)


Mount an external hard drive with full ownership and permissions (sudo or root)

Mount it like this:

mount -t ext4 -o umask=0022,gid=yourGroupID,uid=yourUserID /yourDevice /yourMountPoint

Where yourGroupID and yourUserID are the IDs for your own user (you can find the IDs in the /etc/passwd and /etc/group files respectively).


What is the screenshot shortcut on 17.10 when using Unity?

You can hold CTrl and Shift and Print Screen and it will save it to your clipboard instead of your Pictures directory


How do I create a local repository accessible from a local chroot environment for O/S building?

One strategy that might work would be to mount (with the --bind option) a common folder to the chroot's package cache.  This cache is located at /var/cache/apt/archives/

Using this method would make it so that any command run by apt will operate with the common local archive.

Examples

Having two chroot's share a common apt archive

sudo mount --bind ~/builds/cache <chroot location>/var/cache/apt/archives
sudo mount --bind ~/builds/cache <another chroot location>/var/cache/apt/archives

That would make ~/builds/cache and both chroot's apt archive operating against the same directory.

Havind two chroot's share the local install's archive

sudo mount --bind /var/cache/apt/archives <chroot location>/var/cache/apt/archives
sudo mount --bind /var/cache/apt/archives <another chroot location>/var/cache/apt/archives

Similar to the first one, but now the main install and both chroots will use the same apt archive, ie, apt in all three will look in the same place for downloaded .deb files.

(I thought packages don't directly care about the ubuntu release, just the versions of associated packages.  So you may not need to worry about separate folders for each release, and you could even possibly use the local install's package archive.)

Cleaning up

Lastly, and importantly, in the section about cleaning up the chroot in preparation for the final build, you don't want to run apt clean.  Since apt is now using the same folder across all chroots setup this way, apt clean will essentially clear the archive for all chroots at once.  Instead, within the chroot, run:

umount /var/cache/apt/archives

This will effectively "apt clean" the archive from just the chroot where the command is run, while leaving the common folder untouched.

Bind mounts manual info

The following is a straight copy from the man mount page.  Please take a look at it for full explanation of mount --bind, and possibly to see other ways of using bind.

The bind mounts.
          Since  Linux  2.4.0  it  is possible to remount part of the file
          hierarchy somewhere else.  The call is:

                 mount --bind olddir newdir

          or by using this fstab entry:

                 /olddir /newdir none bind

          After this call the same contents are accessible in two  places.
          One  can  also  remount  a single file (on a single file).  It's
          also possible to use the bind mount to create a mountpoint  from
          a regular directory, for example:

                 mount --bind foo foo

          The bind mount call attaches only (part of) a single filesystem,
          not possible submounts.  The  entire  file  hierarchy  including
          submounts is attached a second place by using:

                 mount --rbind olddir newdir

          Note  that  the filesystem mount options will remain the same as
          those on the original mount point,  and  cannot  be  changed  by
          passing  the  -o  option  along  with --bind/--rbind.  The mount
          options can be changed by a separate remount command, for  exam‐
          ple:

                 mount --bind olddir newdir
                 mount -o remount,ro newdir

          Note  that  the behavior of the remount operation depends on the
          /etc/mtab file.  The first command stores the 'bind' flag in the
          /etc/mtab  file  and  the second command reads the flag from the
          file.  If you have a system without the /etc/mtab file or if you
          explicitly  define  source  and  target  for the remount command
          (then mount(8) does not read /etc/mtab), then you  have  to  use
          the  bind  flag  (or  option)  for the remount command too.  For
          example:

                 mount --bind olddir newdir
                 mount -o remount,ro,bind olddir newdir

          Note that remount,ro,bind will  create  a  read-only  mountpoint
          (VFS  entry),  but the original filesystem superblock will still
          be writable, meaning that the olddir will be writable,  but  the
          newdir will be read-only.


I just ran into this myself, found that the USB cable that was being used to monitor my CyberPower UPS was lose. Fixing the connection caused the process to stop spinning, it was a in a tight loop trying to measure the outcome of select on some file descriptor spinning a CPU core.


I did this in Ubuntu 14.04.3

You need root privileges to do this, so be careful.

sudo su

There is several ways to do this, I did something similar to unblock my wireless card when resume.

Just create a script in /etc/init.d/ (name it as you want, I'll name it "wireless")

nano /etc/init.d/wireless

inside your script, write your commands

#!/bin/sh
install rt2800usb modprobe --ignore-install rt2800usb ; /bin/echo "148f 5370" > /sys/bus/usb/drivers/rt2800usb/new_id' | sudo tee /etc/modprobe.d/rt2800usb.conf
sudo modprobe -v rt2800usb

Save it, CTRL+X then Y (in nano)

Once in the script folder, run

chmod +x /etc/init.d/wireless

And then

update-rc.d wireless defaults

As I said, there's several ways to do this, but this worked for me.


My suggestion is that you install and use Remmina.
Remmina is a powerful remote desktop client, available in the repositories, designed for those who need to access their computers remotely.
Among its many benefits are: supports RDP, VNC, NX, XDMCP and SSH. Quick connections by users directly putting in the server address, viewport fullscreen mode. Enables users to maintain a list of connection profiles. Offers tabbed interface, optionally managed by groups.
To install it with its compatible plugins, open a terminal and run:
sudo apt-get update
sudo apt-get install remmina remmina-plugin-*

Once installed, run it and configure a new connection to your remote server, pressing [Ctrl + N] or going to Connection - & gt; New and configure the remote connection profile with the required parameters:
Name:
Group:
Protocol:

Server:
User name:
Password:
Domain:
Resolution:
Color depth:
Share folder:

Once you have configured all the necessary settings, save the settings by clicking the Save button and from the main interface, you can see all your configured remote connection profiles.
To connect using VNC, select the connection profile, edit the settings, select VNC from the Protocols drop-down menu. Configure basic, advanced, and ssh settings for the connection and click Connect, then enter the user's SSH password.
After the connection to the remote machine is established using the VNC protocol, enter the user's login password from the desktop login interface.
Source: https://www.remmina.org/wp/


How do I install GIMP's "save for web" plugin on Ubuntu 20.04?

You have to install single package with needed plugin:
sudo apt-add-repository universe

sudo apt-get install gimp-plugin-registry


which ubuntu version for oracle application express

I suggest you to have ubuntu server install And install the  tools which you want .

to have a gui you can install one desktop environment like ubuntu, kubuntu, xubuntu,lubuntu etc.


As of 18.04, support for hardware decoding on Kaby Lake is given through the i965-va-driver package. You can check if it works on your system by installing va-driver-all and installing and running vainfo. The output should look similar to this:

> vainfo
libva info: VA-API version 1.1.0
libva info: va_getDriverName() returns 0
libva info: Trying to open /usr/lib/x86_64-linux-gnu/dri/i965_drv_video.so
libva info: Found init function __vaDriverInit_1_1
libva info: va_openDriver() returns 0
vainfo: VA-API version: 1.1 (libva 2.1.0)
vainfo: Driver version: Intel i965 driver for Intel(R) Kaby Lake - 2.1.0
vainfo: Supported profile and entrypoints
      VAProfileMPEG2Simple            : VAEntrypointVLD
      VAProfileMPEG2Simple            : VAEntrypointEncSlice
      VAProfileMPEG2Main              : VAEntrypointVLD
      VAProfileMPEG2Main              : VAEntrypointEncSlice
      VAProfileH264ConstrainedBaseline: VAEntrypointVLD
      VAProfileH264ConstrainedBaseline: VAEntrypointEncSlice
      VAProfileH264ConstrainedBaseline: VAEntrypointEncSliceLP
      VAProfileH264Main               : VAEntrypointVLD
      VAProfileH264Main               : VAEntrypointEncSlice
      VAProfileH264Main               : VAEntrypointEncSliceLP
      VAProfileH264High               : VAEntrypointVLD
      VAProfileH264High               : VAEntrypointEncSlice
      VAProfileH264High               : VAEntrypointEncSliceLP
      VAProfileH264MultiviewHigh      : VAEntrypointVLD
      VAProfileH264MultiviewHigh      : VAEntrypointEncSlice
      VAProfileH264StereoHigh         : VAEntrypointVLD
      VAProfileH264StereoHigh         : VAEntrypointEncSlice
      VAProfileVC1Simple              : VAEntrypointVLD
      VAProfileVC1Main                : VAEntrypointVLD
      VAProfileVC1Advanced            : VAEntrypointVLD
      VAProfileNone                   : VAEntrypointVideoProc
      VAProfileJPEGBaseline           : VAEntrypointVLD
      VAProfileJPEGBaseline           : VAEntrypointEncPicture
      VAProfileVP8Version0_3          : VAEntrypointVLD
      VAProfileVP8Version0_3          : VAEntrypointEncSlice
      VAProfileHEVCMain               : VAEntrypointVLD
      VAProfileHEVCMain               : VAEntrypointEncSlice
      VAProfileHEVCMain10             : VAEntrypointVLD
      VAProfileHEVCMain10             : VAEntrypointEncSlice
      VAProfileVP9Profile0            : VAEntrypointVLD
      VAProfileVP9Profile0            : VAEntrypointEncSlice
      VAProfileVP9Profile2            : VAEntrypointVLD

This is good enough to watch 4K video with dedicated video player programs (e. g. mpv, vlc, totem), even on low power hardware.

However, no web browser on linux supports using VA-API yet, so watching any video from a browser will not use hardware accelerated decoding. Instead, CPU decoding will be used, which, depending on your CPU speed, will or will not work well. On low power laptop hardware you will likely experience stuttering.


How do I find out if I have a separate boot partiton from the Live CD?

You can check your fstab to see if you ever had a boot partition.
Boot with a live CD and mount your main partition (sda5).

sudo mount /dev/sda5 /mnt

Then show the contents of the fstab file

cat /mnt/etc/fstab

If you ever had a boot partition on e.g. sda4 you would see a line like this:

/dev/sda2    /boot     ext3     defaults    0  0


Why is "Connect to Server" bookmarking gone in 11.10?

When I have already established a connection using the Connect to Server, and it appears in the side panel of Nautilus under the Network heading, the option of "Add Bookmark" appears for me if I right click on my connected share. When I click and Add Bookmark, it does add a bookmark for the connection under the bookmark section for me, Hope this helps...

Here are screen shots of what it will look like when you right click on a connection, and add a bookmark.


Stuck in grub rescue after Windows install

This is a quick and simple method of restoring a broken system's GRUB 2 files. The terminal is used for entering commands and the user must know the device name/partition of the installed system (sda1, sdb5, etc). The problem partition is located and mounted from the LiveCD. The files are then copied from the LiveCD libraries to the proper locations and MBR. It requires the least steps and fewer command line entries than the following methods.

Boot to the LiveCD Desktop (Ubuntu 9.10 or later).
Open a terminal by selecting Applications, Accessories, Terminal from the menu bar.
Determine the partition with the Ubuntu installation. The fdisk option "-l" is a lowercase "L".

sudo fdisk -l

If the user isn't sure of the partition, look for one of the appropriate size or formatting.

Running sudo blkid may provide more information to help locate the proper partition, especially if the partitions are labeled. The device/drive is designated by sdX, with X being the device designation. sda is the first device, sdb is the second, etc. For most users the MBR will be installed to sda, the first drive on their system. The partition is designated by the Y. The first partition is 1, the second is 2. Note the devices and partitions are counted differently.

Mount the partition containing the Ubuntu installation.

sudo mount /dev/sdXY /mnt

Example: sudo mount /dev/sda1 Note: If the user has a separate /boot partition, this must be mounted to /mnt/boot

Run the grub-install command as described below. This will reinstall the GRUB 2 files on the mounted partition to the proper location and to the MBR of the designated device.

sudo grub-install --root-directory=/mnt/ /dev/sdX

Example: sudo grub-install --root-directory=/mnt/ /dev/sda
6. Reboot
7. Refresh the GRUB 2 menu with sudo update-grub

reboot...done....


Media keys inconsistently working on different applications. 18.04

I discovered the answer through googling 'Ubuntu Media Keys Focus'.

Once Chrome takes media key focus, it keeps it, but you can turn off it's control of media within it's deeper settings.

Use this, and disable the media key handling. Restart Chrome.

chrome://flags/#hardware-media-key-handling

I learned it from here:  https://www.omgchrome.com/chrome-google-music-media-keys/


My PC restarts with NO Warning!I am using ubuntu 12.04

I had a similar issue and couldn't seem to track it down. It ended up being heat related , it wasn't my CPU overheating but something else on my motherboard causing the random reboot. In this case, the system would poweroff instantly, then restart itself. I stumbled upon the answer by taking off the case side and pointing a box fan at it.


unity-control-center has unmet dependencies after kernel update 4.4.0-47 generic

Playing around with the terminal, I randomly came out with a solution, it is as follows :-

Install Synaptic Package Manager

sudo apt-get install synaptic

Now go to the Synaptic package manager through the start or by typing sudo synaptic on the terminal

Next, search for the package with unmet dependencies (in my case libgl1-mesa-dev).

Mark the package for complete removal

Click Apply on the top

Synaptic will first resolve the unmet dependencies and then it will completely remove the package, you can install it again later.

Enjoy!


Traverse through all folders and renaming all files inside folder sequentially 1.*, 2.*, 3.*

I don't believe you will find a ${file/?/?} parameter substitution that produces a numeric sequence - especially not a per-folder numeric sequence. Instead you will need to set and increment a variable.

What parameter substitution (specifically, ${file##*.}) will be useful for is extracting the file extension, so that you can re-add it to the sequential file name. So for example you could do:

#!/bin/bash

shopt -s nullglob

for imageFolder in */; do
  cd "$imageFolder" || continue
  n=1
  for file in *.*; do
    echo mv -- "$file" "$((n++)).${file##*.}"
  done
  cd -
done

or (with a subshell)

#!/bin/bash

shopt -s nullglob

for imageFolder in */; do
(
  cd "$imageFolder" || exit
  n=1
  for file in *.*; do
    echo mv -- "$file" "$((n++)).${file##*.}"
  done
)
done


Upgrade djvu from 4.9-1 to 4.9-2 from the Debian Sid repository. It worked for me.

Instructions found here.


If you boot your computer from the new Ubuntu 12.10 disk you should have an Upgrade option, but I prefer upgrading via Software Updater.


First of all , if you are still new to this you need to try it out first before fully switching. Try wubi before fully installing , it allows you to install linux in dualboot as  a regular application , that can be removed via control panel. IF you have already decided to fully switch then you need to do this:

Download the iso from ubuntu.com
Buy a DVD disc or if your computer is fairly new 2-4 years old  get a 1+ gb USB drive.
Get a disc burning program like Nero or my personal favorite "Active iso burner" and make sure your computer has a disc writer ( skip this step if you plan on using a usb)

in case you plan on using a usb , get unetbootin or a simillar program and burn the                  image on the usb(usb sticks are erasable so you won't waste it you can use any stick you have)

Stick the disc in the drive or the usb in the slot and reboot.
Go in the bios menu by hitting the delete key or one of the F keys ( the key to press is shown at POST something like "Press the X key to enter bioss setup" )
Go to the boot options menu ( it's not named that in some cases might be  boot order or just boot)
Set the boot order to boot first either from the USB or CD.
Reboot and let the linux live CD boot
Start setup and follow the instructions

*IF there is a driver problem with some devices ask here or google it


How to configure my touchpad to switch between workspaces with a swipe

Dont know about unity but you can do in Gnome, move your cursor over the dash/launcher , swipe with 2 finger boom workspaces switch instantly.

Cheers


How to make folder writable to 2 users in different groups?

Create a group, put both users in this group and type:

chown -R GROUPNAME /var/www/test7.com/*

I hope this helped you,
Daniel


There was a similar problem that struck me after reading this question here on AskUbuntu and checking my VPS, only to see a bazillion of brute force attempts. That is when I decided to take action.
Now according to the question I linked to, if you would like to see failed login attempts on your machine over ssh (could be brute force attempts or anything), try typing this:
grep sshd.\*Failed /var/log/auth.log | less

If the output consists of multiple lines, that is many brute force attempts, especially if they have happened between short intervals, you might want to do the following pieces of action:
Change the ssh configuration file
To do this, open the file located at /etc/ssh/sshd_config with your favourite editor, like this vim /etc/ssh/sshd_config.
1. Try to move ssh from port 22:  Now locate the line that reads:
# What ports, IPs and protocols we listen for
Port 22

and comment out Port 22, and use anyone you might like. Example:
# What ports, IPs and protocols we listen for
# Port 22
Port 28934

Please remember that ports below 1024 need special (root) permission. I do not know how this could interfere with it, but I am just saying.
2. Disable Root logins via ssh: Since the root username is predictable and provides complete access to your system, providing unfettered access to this account over SSH is unwise. Locate the line reading PermitRootLogin and set it to no.
PermitRootLogin no

3. Disable password authentication: Generate and use SSH keys to log into your system. Without passwords enabled, attackers will need to guess (or steal) your SSH private key in order to gain access to your server. Something that is very very difficult. Proceed to find the line that reads PasswordAuthentication and set it to no
PasswordAuthentication no

!WARNING! Before doing so, please consult this guide over here on how to set up certificate authentication.
NOTE: After you have made the changes use sudo /etc/init.d/ssh restart. To connect to another port via ssh use: ssh username@hostname.com -p <port_number>.
Setup a firewall
Please check out this guide on how to set up the extremely powerful and effective firewall, which is integrated into Linux, IPTables.
Setup scripts to help you with security
One that I use personally and quickly comes to mind is Fail2Ban. Fail2ban will monitor your log files for failed login attempts. After an IP address has exceeded the maximum number of authentication attempts, it will be blocked at the network level and the event will be logged in /var/log/fail2ban.log. To install it: sudo apt-get install fail2ban
Check command history via ssh
There is a linux command, named history, which allows you to see which commands have been input up until that point. Try typing history in a terminal to get to see all commands up to that point. It could help if you were root.
To search for a particular command try: history | grep command-name
To list all commands after ssh: fc -l ssh
You can also edit commands using vi (haven't tried it vim, though I assume it works as well): fc -e vi
You can also delete the history: history -c
NOTE: If you are not a fan of the command history there is also a file in your home directory (cd ~), called .bash_history (if you are using bash) that you can cat to see all that has been typed in the bash shell.


Gnome Shell installation problems in Ubuntu 13.10

This command will delete your configuration files. It will reset all the settings. You will not be able to undo this!

Press Ctrl+Alt+T and run these commands:

For Gnome 2

rm -rf .gnome .gnome2 .gconf .gconfd .metacity

For Gnome 3

rm -rf .gnome .gnome2 .gconf .gconfd .metacity .cache .dbus .dmrc .mission-control .thumbnails ~/.config/dconf/user ~.compiz*


Why does lsmod command show many modules with size of 16384

These are not the size of modules, to get the real size of these modules you can run something like:

lsmod | grep 16384 | cut -f1 -d ' ' | xargs modinfo | grep filename |\
 grep -o '/.*' | xargs stat -c "%s - %n"

Which outputs (in bytes):

...
19086 - '/lib/modules/4.4.0-78-generic/kernel/sound/core/seq/snd-seq-midi.ko'
21470 - '/lib/modules/4.4.0-78-generic/kernel/sound/core/snd-hwdep.ko'
15798 - '/lib/modules/4.4.0-78-generic/kernel/sound/core/seq/snd-seq-dev
...

The "16384" is the size of memory used by that module in bytes which is equal to "16KiB". And as I know it's just a default number and also the minimum that can be used, if you look carefully you can see that there is no module with the size less than of 16384.

I guess this minimum is related to PTHREAD_STACK_MIN, run:

getconf PTHREAD_STACK_MIN

you will get:

16384

From here:

  The stack size attribute determines the minimum size (in bytes) that will be allocated for threads created using the thread attributes object attr.

read more and more.


Solution given by OP in comments:

  Had to disable the HTML5 Audio in the Labs portion. Once I did that, it plays fine.


Let's focus on the command-line invocation first. My guess is that your PATH includes the path of the old installation (the one in your home directory) first. Or perhaps it's just a question of doing a rehash. Here's what I'd suggest:

Open a new terminal window (one way to make sure that paths are refreshed).
run racket --version, make sure that it's still 6.1.
run which racket to see which version of racket you're running. I'm guessing it'll be one installed in your home directory.
run echo $PATH to see what your PATH looks like. My guess is that the path to the one installed in your home directory will occur before the one installed using the ppa.

If everything I've supposed is true, then you can probably solve this by deleting the racket directory in your home directory (or, more conservatively, by moving it to /tmp so you can get it back if you want).

After removing the racket from your home directory you need to tell your shell (bash), that the command has disappeared from previous location, because bash shell remembers location of commands already used.  You can remove this command hash table either by running: hash -r or just closing existing shell instances and opening new terminal window.


When xubuntu 13.04 was released I had upgraded to it. But as soon as i upgraded, my wifi stopped working. It was showing all the connections, but unable to connect to them. So, I switched back to 12.10.
In your case, at least this version is able to connect (for a while though).
If it is possible, I would suggest you try xubuntu 12.10 or better 12.04, and see if the problem persists.


Edit the files named /etc/init/ttyX.conf (where X can be 1 to 6) as follows:

For example tty1 :

sudo nano /etc/init/tty1.conf

Comment this line:

exec /bin/login -f USERNAME < /dev/tty1 > /dev/tty1 2>&1

And append below line :

exec /sbin/getty -8 38400 tty1


In the Bugreport that you linked, there is one comment that explained why some people could not login at all (maybe similar to your problem). The solution for that is to install cracklib-runtime with the default cracklib dictionary of /usr/share/dict/cracklib-small. According to that guy, libpam-pwquality depends on it but it is not listed as a dependency, which causes the check whether a password is strong enough to always fail.


Help with installing/dual booting Windows 10 on a Ubuntu laptop?

For me it was easier to install Ubuntu after windows. Install Windows with the needed partition space you specify, then run the Ubuntu installer via bootable USB. Ubuntu will see the unpartitioned space. You can then install there. With this, you will need to boot into Ubuntu using the F9 option at BIOS boot so you can boot Ubuntu.  Hope this helps!


Enabling Kubuntu-Desktop in Ubuntu 12.04

You need to log out first, click the circular Ubuntu icon near the password prompt and choose "KDE". Now, you can log in and use KDE. Reopen this menu and select "Ubuntu" if you like to use Unity again.


Eclipse Juno won't open gui java apps when run with gksudo

There is and there was never a reason to start Eclipse with administrator privileges.

Place your Eclipse application folder in /opt and grant read access.

sudo chmod -R +r /opt/eclipse

All user files, workspace etc. are stored in your home folder.

More about Eclipse here.


wicd use_settings_globally works but won't connect automatically

So I did some probing in the wicd-daemon.py and found the code block relevant to auto-connect.

I searched some of the code there which lead me to https://bugs.launchpad.net/wicd/+bug/1440952

I substituted the code in and viola, I can connect networks configured with the same ESSID.

     for x, network in enumerate(self.LastScan):
        - if self.config.has_section(network['bssid']):
        + essid_key = "essid:%s" % network['essid']
        + if self.config.has_section(network['bssid']) or self.config.has_section(essid_key):
                        if self.debug_mode:
                            print network["essid"] + ' has profile'
                        if bool(network.get('automatic')):


How to prevent Thunderbird from updating automatically?

Referring to your second question:

Avoiding automatic updates for a specific package

Install synaptic package manager if you haven't done so already

sudo apt-get install synaptic

Open it up and search for the package in question, e.g. thunderbird. Mark the package you want to modify and head to Package --> Lock version.

Do the same for all thunderbird related packages and thunderbird will not get upgraded until you remove the version lock flag.


Manually activate Network Manager Applet

Run nm-applet.  Make sure you have a panel running.
If you need command-line interaction capability, check out wicd and wicd-curses.


Plasma shows themes, etc. as installed, though they are not and vice versa

Few words of the KDE Get Hot New Stuff (GHNS)

This is with the KDE Frameworks 5

Glossary: https://userbase.kde.org/Glossary#Get_Hot_New_Stuff

  Get Hot New Stuff (GHNS) is an open standard that makes it easy for
  users to download and install various extensions for their
  applications. Our implementation of GHNS is used by Plasma (for
  example to get new desktop themes), and by many applications and
  widgets.

When you are using the System Settings Add-On Installer the bookkeeping (installed, removed, ...) is made to the knsregistry xml file at the $HOME/.local/share/knewstuff3/. Plasma theme registry is at : $HOME/.local/share/knewstuff3/plasma-themes.knsregistry.

Sample plasma-themes.knsregistry:

There are also other ways to install and remove the themes, service menus, etc. You could install and remove things by hand, with the distribution package management (apt) or with the KDE tools (kpackagetool5). So the system settings can't only rely the knewstuff registers. The browsers are showing the real situation. What themes are at the right place and have the right format.

Plasma desktop theme browser window(kcmshell5 kcm_desktoptheme):

The plasma system settings desktop theme module is showing the themes from the /usr/share/plasma/desktoptheme/ and $HOME/.local/share/plasma/desktoptheme/.

Few tests

1) Testing with the 'Adapta KDE' desktop theme

Installation: Installs fine

marked to the plasma-themes.knsregistry
unpacked to the $HOME/.local/share/plasma/desktoptheme/

Removal from the plasma Desktop Theme browser

removed from the $HOME/.local/share/plasma/desktoptheme/
plasma-themes.knsregistry status is still installed !

Removal from the 'System Settings Module Add-On Installer'

removed from the $HOME/.local/share/plasma/desktoptheme/
removed plasma-themes.knsregistry

2) Testing installation with the 'K10ne Next' theme

Executing with the Konsole:

$ kcmshell5 desktoptheme

Error =>

Command failed "kpackagetool5 -t Plasma/Theme -r /tmp/k10next_final.7z"
Command ' "kpackagetool5 -t Plasma/Theme -i /tmp/k10next_final.7z" ' failed with code 4

But the plasma-themes.knsregistry has:

<status>installed</status>

and the 'System Settings Module Add-On Installer' shows:

Executing

  kpackagetool5 -t Plasma/Theme -i /tmp/k10next_final.7z

More information:

  Error: Installation of /tmp/k10next_final.7z failed: Could not open
  package file, unsupported archive format: /tmp/k10next_final.7z
  application/x-7z-compressed

Note !

It is possible to unpack the k10next_final.7z with the Ark to the $HOME/.local/share/plasma/desktoptheme/ .

Repairing the GHNS

The knsregistry files are text files (xml). You could remove the part between the <stuff>... </stuff> if there are already removed files.


Can't move files to trash without any permission issues

This is a bug in nautilus, since the same doesn't happen in Trusty (as you found out by yourself); the explanation for this behavior might be that nautilus always tries to delete the files reached through the /home path as being physically located in the /home partition even when they're reached through a symbolic link to a folder physically located in another partition: in this case "trashing" the file like usual fails because the target file cannot be be moved to the user's Trash, hence the prompt to delete it immediately instead.


Skype Video Call Screen keeps flashing and Camera Problem

I also have chipset Intel 915 and I had the same problem with video calls in Skype.

Upgrade to Ubuntu 16.10 (from 16.04.1) helped me and completely solved this problem.

I believe that problem is solved in new version of Linux kernel. You can also try this fix if you don't want to upgrade.


Firefox 52 ended support for NPAPI plugins other than Flash.

For more information see Firefox 52 Release Notes and the accompanying blog post.