One of the selectors introduced in CSS 3 was the :target pseudo-class selector. But what is a pseudo-class? A pseudo-class represents a state of a selector like :hover, :active, :first-child and their name starts with a single colon(:). So :target will also represent a state of a selector or an element.
Now we know that URLs can have a section focused using the # character mostly using an anchor link. For :target, the element being linked to it is the target element. Or let me rephrase it for a simpler explanation. The :target selector can be used to style the current active target element mention in the URL by the # character.
The following example might help better. Suppose we have a website URL step4wd.com/dummy.html and the following tag in our HTML code:
<div id="example">Example</div>
Plus the following CSS code:
div:target {
color: blue;
}
The div will have the default colour for the text. But if we change the URL to step4wd.com/dummy.html#example, the text of the div will change to blue colour and that is the trick our :target is all about.
This seems so simple but numerous wonders can be achieved with it like photo gallery, modal boxes etc.
Converting documents from JPG to PDF or vice versa, compressing and scaling images is a relatively common task for me. After installing the required ImageMagick package in Ubuntu, I tried running the convert command but to my surprise, got the following error message:
$ convert source.jpg destination.pdf
convert-im6.q16: attempt to perform an operation not allowed by the security policy `PDF' @ error/constitute.c/IsCoderAuthorized/408.
After little searching I found the resolution as mention below.
Steps to Follow
Open the Terminal on type the command:
$ sudo vim /etc/ImageMagick-6/policy.xml
You will get the output based on the devices attached to you system:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE policymap [
<!ELEMENT policymap (policy)+>
<!ATTLIST policymap xmlns CDATA #FIXED ''>
<!ELEMENT policy EMPTY>
<!ATTLIST policy xmlns CDATA #FIXED '' domain NMTOKEN #REQUIRED
name NMTOKEN #IMPLIED pattern CDATA #IMPLIED rights NMTOKEN #IMPLIED
stealth NMTOKEN #IMPLIED value CDATA #IMPLIED>
]>
<!--
Configure ImageMagick policies.
Domains include system, delegate, coder, filter, path, or resource.
Rights include none, read, write, execute and all. Use | to combine them,
for example: "read | write" to permit read from, or write to, a path.
......
Rules are processed in order. Here we want to restrict ImageMagick to only
read or write a small subset of proven web-safe image types:
<policy domain="delegate" rights="none" pattern="*" />
<policy domain="filter" rights="none" pattern="*" />
<policy domain="coder" rights="none" pattern="*" />
<policy domain="coder" rights="read|write" pattern="{GIF,JPEG,PNG,WEBP}" />
-->
<policymap>
<!-- <policy domain="system" name="shred" value="2"/> -->
......
<policy domain="coder" rights="none" pattern="PS" />
<policy domain="coder" rights="none" pattern="EPS" />
<policy domain="coder" rights="read | write" pattern="PDF" />
<policy domain="coder" rights="none" pattern="XPS" />
</policymap>
The only change is the highlighted line in which none was replaced with read | write and the file was saved. Now running the convert command again worked as expected 👍🏼
The first time I purchased Dell's XPS 13 notebook was in 2015 and couldn't be more satisfied. Now I own Dell XPS 13 9380 with Ubuntu 18.04 pre-installed. After initial testing the hardware, I immediately installed a fresh 19.04 and everything was well supported.
However there is no proper was of enabling or disabling the Touchpad. In the Knowledge Base provided by Dell, there is no mention of Ubuntu even though the OS is officially supported. Dell had another link to the Linux issue which didn't look easy to follow. So I am sharing a more simpler fix.
Steps to Follow
Open the Terminal on type the command:
$ xinput list
You will get the output based on the devices attached to you system:
I was installing ubuntu-sdk on my device, accidently I run sudo apt-get update and it broke some links and my phone become unusable. So i reinstall ubuntu OS on it.
In order to install ubuntu or to upgrade its channel, follow this tutorial.
Commands to be Executed
Open the Terminal on Ubuntu Desktop.
Install the ubuntu-device-flash package
The ubuntu-device-flash package is main tool for installing Ubuntu for devices. Install the package:
sudo apt-get install ubuntu-device-flash
Install phablet-tools package
The phablet-tools package provides a Desktop tools useful when working with a USB-connected Ubuntu device.
sudo apt-get install phablet-tools
Installing ubuntu-device-flash also adds two important Android tools you frequently use: adb and fastboot
Supply a recovery image with adb enabled, which ubuntu-device-flash will use temporarily while doing its work
Expecting the device to be in the bootloader... waiting
You can put a Aquaris E5 in the bootloader by holding down Power + Volume Up for a few seconds, releasing the Power button when the red LED lights as the machine reboots, and then selecting fastboot from the device's boot menu.
UbuntuTouch (also called UbuntuPhone) is new and under active development. One usual expectation from any user is to be able to sync data with services. As of today, it comes with the ability sync with Google only. Problem is Google is really deep and evil when it comes to surveillance. So I tried to sync with my ownCloud and here is what I had to do:
Tools Required
ownCloud server running which would be accessible from the Internet with Contacts and Calendar App installed (whichever is required for sync).
SyncEvolution which is now pre-installed in UbuntuTouch.
Another alternate is to download the certificate and place it in on your UbuntuTouch device. Add the SSLServerCertificates switch to specify the location of the certificate:
In this tutorial, we will learn how to execute a bash script at upstart.
What is Upstart?
Upstart is an event-based replacement for the /sbin/init daemon which handles starting of tasks and services during boot, stopping them during shutdown and supervising them while the system is running.
Job will be started when the filesystem is mounted and net-device-up IFACE=lo event, which signifies the local network (for example, 127.0.0.0 for IPv4) is available.
Stop on conditon:
stop on runlevel [016]
This ensures the job will be stopped on shutdown[0], when switching to single-user mode[1] and on reboot[6].
Runlevels for Debian and Ubuntu systems are generally as follows:
0 : System halt.
1 : Single-User mode.
2 : Graphical multi-user plus networking (DEFAULT)
3 : Same as "2", but not used.
4 : Same as "2", but not used.
5 : Same as "2", but not used.
6 : System reboot.
Script
All job files must have either an exec or script stanza. This specifies what will be run for the job.
script
exec bash -c '/opt/local/our-sync-pkg-2.0/sync_users start'
end script
exec gives the path to a binary on the filesystem and optional arguments to pass to it.
Executing bash script
By default, Upstart uses "/bin/sh" to execute script sections. You can change the default shell.
But it can done in simplest way by executing this line:
In this tutorial we will look through how to package some simple hello world script.
A quote from debian maintainer's guide:
One thing is certain, though: to properly create and maintain Debian packages takes many hours. Make no mistake, for our system to work the maintainers need to be both technically competent and diligent.
We have many methods to create a Debian package In this tutorial we will use FPM.
This method requires minimum effort follow this if you don't want to upload to PPA. However it requires ruby gem and package name FPM. check wiki for further details.
mkdir -p ~/via-fpm/debian/usr/bin/
cd ~/via-fpm/debian/
touch ~/via-fpm/debian/usr/bin/hello-via-fpm.sh
gedit ~/via-fpm/debian/usr/bin/hello-via-fpm.sh
Add following lines to script.
#!/bin/bash
echo "hello debian packaging via fpm"
Save and close that file.
whatever folder structure you will put in your source folder it will automatically copied into respected folders. There is no need to to copy them. For example if you want to put some sources file in /opt/local/sources then you must have same structure in you application source.
Similarly usr/bin/ files will automatically copied to their respected folder in this case that will be /usr/bin.
Next we will come towards the scripts that will automatically run like preinstall , post install , pre un-install and post un-install . If you want to create user, directories, set permissions then these scrips are for you. You can use bash here.
In this demo we will use "postinst" script to set permission for ~/via-fpm/debian/usr/bin/hello-via-fpm.sh
create postint file in described location and add the following code.
#!/bin/bash
set -e
sudo chmod +x ~/via-fpm/debian/usr/bin/hello-via-fpm.sh
exit 0
It't time for packaging.
cd ~/via-fpm
fpm --epoch 1 -s dir -e -C debian \
-a all -m "uncle demo <UncleDemo@example.com>" \
--description "our absurd debian package for demo via fpm" \
-v 1.0 -t deb -n hello-via-fpm --after-install debian/opt/local/postinst
Switches that we have used and their meaning
-epoch: Used for epoch value is somehow versioning number
-e: Edit the package spec before building. (default: false)
-C: Change directory to here before searching for files
-a: The architecture name. Usually matches 'uname -m'. For automatic values, you can use '-a all' or '-a: native'. These two strings will be translated into the correct value for your platform and target package type.
-m: The maintainer of this package. (default: "djhaskin987@djhaskin987-S301LA")
--description: add description
-v: specify version number
-t: output type
-n: Name to give to the package
--after-install: file to run after post install
Why FPM:
Because it will automatically create necessary files like control, rules and lot other necessary stuff for you. There are other proper ways to do that using official Debian package management through which you can upload your package to PPA. That we will discuss in next demo.
INSTALLATION:
To install that package either open via Ubuntu software center or run command sudo dpkg -i hello-via-fpm_1.0_all.deb
LAST CHECK:
Now try to run command from shell hello-via-fpm.sh to see that your package is installed now and further you can create your own with customizations.
The latest version of LibreOffice is here but unfortunately its not going to be available in Ubuntu 14.04 and 12.04 by default. But the good news is that we can upgrade existing version by typing these commands:
Ubuntu has a special account, named Guest, which allows access (login) to the system without asking for any password. Although there are limitation applied to this account but maybe its not always desirable to have it. These steps will help in disabling it (tested under 12.04 and 14.04):
Open the file /etc/lightdm/lightdm.conf and add the following line to it at the end:
allow-guest=false
If the file lightdm.conf is missing, then paste the following contents in the blank file:
If you have made a fresh clean installation of Ubuntu 13.10, you would have noticed one announced missing feature. The Ubuntu One icons and context menu is missing from Nautilis (File Manager). Why is it missing?? Couldn’t find a valid reason even in Launchpad although Ubuntu One was supposed to be important to Ubuntu. Anyway…
To fix, you will need to install to packages from 13.04 and restart Nautilis. Follow these steps:
Drupal is a popular CMS built in PHP, which is flexible and powerful. Currently in version 7 and the next version 8 is due in some time. Drupal has a way to Log and Report Errors. Like almost all CMS, it also periodically checks for new updates to the core, as well as themes and modules. Once an update is detected, it will Log Report it. It will also report about other errors in your code.
This all helpful in making your there are no bugs and security holes left for your site to be hacked. However you would not like the visitors and viewers of your site to have warning messages shown at the top of every page. To solve this issue, Drupal has a way to turn them Off for the visitors and let it remain On for the admin user.
Just login to your site as admin and navigate to Configuration (at the top), then under Development click on Logging and errors. You can directly go to it by pasting this URL segment at the end of your drupal home page URL: admin/config/development/logging
You will see a screen similar to the picture below. Just select None and click on Save configuration to make it effective.
It is now possible to have multiple audio tracks in a single video. This is becoming common for Movies and Documentaries. This way a single video is good for serving people of different lingual backgrounds. However, like me you might not be interested in all those tracks. In this tutorial, we will remove all the unwanted tracks.
The tool we will be using is avconv and in a previous post I have mentioned how to install it in Ubuntu, so I will not be going into the installation part again.
Check how many Tracks are there
First of all we need to check on the track details and for that, run the following command (the extension can be mp4, mov, mkv, avi or any other):
avconv -i file_name.mkv
In my case, I got the following output:
avconv version 0.8.6-6:0.8.6-1ubuntu2, Copyright (c) 2000-2013 the Libav developers
built on Mar 30 2013 22:20:06 with gcc 4.7.2
[matroska,webm @ 0xc31d40] Estimating duration from bitrate, this may be inaccurate
Input #0, matroska,webm, from 'file_name.mkv':
Duration: 00:46:15.28, start: 0.000000, bitrate: 768 kb/s
Stream #0.0(eng): Video: h264 (High), yuv420p, 1280x720, PAR 1:1 DAR 16:9, 25 fps, 25 tbr, 1k tbn, 50 tbc (default)
Stream #0.1(rus): Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s (default)Stream #0.2(eng): Audio: ac3, 48000 Hz, 5.1, s16, 384 kb/s
At least one output file must be specified
The lines in bold tell us how many tracks are there.
Removing the track
Since I have no interest in Russia audio, I would like to remove it. In my case I would like to keep the second track. Here is the command:
To change the Screen Resolution in Ubuntu, simply type Display in the Unity Launcher and run the application. The snapshot of the Display application is taken from Ubuntu 12.10 and is also the same in previous versions also. Similar application is available in other Linux distributions.
But there is a handy command that can do the same thing even faster or can help you create a script (depends how creative and productive you plan to be). The command is simple:
Document Foundation, the developers behind LibreOffice released Version 4.0 on 7th February 2013. Ubuntu 12.04 however is still stuck with Version 3.5 and Ubuntu 12.10 with Version 3.6 of LibreOffice. Its always nice to be up-to-date with the latest versions. This is what is covered in this post.
The first step is to install the PPA repository and there are two choices you have.
To Add 4.0 Repository (this will remain limited to 4.0 and its subversions only like 4.0.x):
Today I was installing Ubuntu in my Olives School lab. There are 20 systems in total. After installing it in the first PC, I ran the Update and there were 443 of them which amounted for 337MB approx. As it can be imagined it took some time to get the first PC updated. This was clearly not what I was going to do with the rest and I had to come up with a solution.
When Ubuntu downloads these updates, it places them in /var/cache/apt/archives/ folder. In fact even after installing updates, they are not removed from the system. So a solution was simple:
Copy all the downloaded packages to a USB
On the next PC, run the command:
sudo cp [path-to-usb]/* /var/cache/apt/archives
Once all the files have been pasted, run the Update Manager tool and it will tell you that updates have been
downloaded but not yet installed.
Drupal Logging and Errors
