Category Archives: Tecnologia

How to open PDF files (and other formats) through Mozplugger on Ubuntu

This article comes as a useful help for all Linux (Ubuntu) users, which will be presented with a new way of opening PDF files in the browsers compatible with this operating system. First of all, most of you probably know that Google Chrome is capable of doing this by default, without the user being required to make a particular setting.

However, Firefox does not currently have this built in feature, so it needs some help (usually in the form of a plugin) in order to open the PDF files you download or see online. In addition to the official plugin from Adobe (which contains numerous bugs and can sometimes be really annoying because if its way of loading PDFs), there is the option known under the name of Mozplugger. This is actually a plugin that allows the integration of different applications with the Firefox browser so that it can open some files not recognized automatically by default. If you want to install Mozplugger, the following simple steps are required and can be done by anyone.

After installing Mozzplugger, the following text muse be written in mozpluggerrc:

application / pdf: pdf: PDF file
application / x-pdf: pdf: PDF file
text / pdf: pdf: PDF file
text / x-pdf: pdf: PDF file
application / x-postscript: ps: PostScript file
application / postscript: ps: PostScript file
repeat noisy swallow (Evince) fill: Evince “$ file”

After making these changes, a restart is totally recommended. If you do not restart your browser right after that, changes might not take the desired effects. You will surely enjoy everything this great plugin has to offer. Not only will you be able to read PDFs directly in your browser, but there will also be some extra formats that you never thought they could be read directly from Firefox.

How to Get Rid of the Root Password on Linux

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If you are a Linux user, particularly Ubuntu, and are the only person that uses your computer, sometimes the fact that your operating system constantly requires for your password every time you log in, then at a certain moment you might want to decide to get rid of it. All you need to do is to follow the next steps carefully and you will be ready to go.

Run a new terminal. This is essential, since, as you already know, every important command and feature of Ubuntu and Linux in general must be done in this way
Run the command ‘sudo visudo’. This will at first require the current root password, as every line starting with ‘sudo’ does.
Type the root password and hit return
A new document will now open in your terminal, which will require some editing. Specifically, a new line should be added in the end of this document. This line is ‘username ALL=NOPASSWORD:ALL’. As you can guess, this will make your operating system stop asking about your root password every time you log in, regardless of the user you use for this process.
Save the edited document and make sure the changes are active.
Restart your computer and check to see whether you can log in without your root password.

As you can see, getting rid of the root password is a rather easy process and sometimes it will save you a lot of time. However, make sure you only do this if you are the only person who uses your account on your operating system, because otherwise your security will be exposed.

This password removal tweak will also work for ‘sudo’ commands as well, making it even simpler for you as a Linux user.

Terminate unresponsive programs on Ubuntu

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Xkill is part of the X11 utilities pre-installed in Ubuntu and a tool for terminating misbehaving X clients or unresponsive programs. You can easily add a shortcut key to launch xkill with the steps below:
– Go to System > Preferences > Keyboard Shortcuts.
– Click the Add button to create a custom shortcut.
– Enter xkill to both the Name and Command boxes and click the Apply button.
– Click on Disabled at the xkill row in the Keyboard Shortcuts window (Disabled is then changed to New shortcut…).
– Press a new key combination, e.g. Ctrl+Alt+X (New shortcut… is then changed to Ctrl+Alt+X).
– Click the Close button.
Xkill is ready for use. Press the above key combination to turn the cursor to an X-sign, move the X-sign and drop it into a program interface to terminate the unresponsive program, or cancel the X-sign with a right-click.

Changing the default text editor on Ubuntu

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There is a few software that will use the editor command to find out what text editor to use. Example commands will be dch to add a new .deb changelog entry, revision control softwares when prompting for commit a message …
There is basically 2 ways for changing the default editor:

1. System Wide
Run Terminal and type:
$ sudo update-alternatives –config editor
And then choose whichever editor you want to be default.

2. User Level
As a user, you cannot change the setting for the whole system, but you can add an alias for editor to let say vim.
Open and edit ~/.bashrc and add:
alias editor=vim
Next time you will open a bash prompt, your default editor will be vim.

How to Install Inkscape on Linux (with special instructions for Ubuntu)

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Inkscape is an open-source SVG editor with capabilities similar to Illustrator, CorelDraw, Visio, etc. Supported SVG features include basic shapes, paths, text, alpha blending, transforms, gradients, node editing, svg-to-png export, grouping, and more. Its main motivation is to provide the Open Source community with a fully XML, SVG, and CSS2 compliant SVG drawing tool.
These are the founding goals for Inkscape:
– Full SVG (plus XML, CSS2) compliance
– Core written in C/C++
– Gtk-based user interface following the standards set out in the GNOME Human Interface Guidelines (HIG)
– Emphasis on a small core and extensibility. Usually Inkscape’s extensions are always first-class so we can say “no” to features in the core without guilt.
– Open, community-oriented development processes
– Baseline is the Sodipodi Hydra codebase
Where a better solution cannot be found, default to the way Illustrator does it.

Installing on Ubuntu Linux

Probably the easiest way to install on Ubuntu is to use the apt command.
Open a terminal and type;
sudo apt-get update (enter)
sudo apt-get install inkscape (enter)

Ubuntu Linux Development Versions

As it approaches release, nightly i386 and AMD64 builds of the latest Inkscape development version are provided at http://ubuntu.cafuego.net. On that site, one should select the appropriate Ubuntu or Debian release, then the Inkscape link, and finally the provided package.

Recovering root password under Linux with single user mode

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It happens sometime that you can’t remember root password. On Linux, recovering root password can be done by booting Linux under a specific mode: single user mode.
This tutorial will show how to boot Linux in single user mode when using GRUB and finally how to change root password.
During normal usage, a Linux OS runs under runlevels between 2 and 5 which corresponds to various multi-user modes. Booting Linux under runlevel 1 will allow one to enter into a specific mode, single user mode. Under such a level, you directly get a root prompt. From there, changing root password is a piece of cake.
Some Linux distribution, such as Ubuntu for instance, offer a specific boot menu entry where it is stated “Recovery Mode” or “Single-User Mode“. If this is your case, selecting this menu entry will boot your machine into single user mode, you can carry on with the next part. If not, you might want to read this part.
Using GRUB, you can manually edit the proposed menu entry at boot time. To do so, when GRUB is presenting the menu list (you might need to press ESC first), follow those instructions:
– use the arrows to select the boot entry you want to modify.
– press e to edit the entry
– use the arrows to go to kernel line
– press e to edit this entry
– at the end of the line add the word: single
– press ESC to go back to the parent menu
– press b to boot this kernel
The kernel should be booting as usual (except for the graphical splash screen you might be used to), and you will finally get a root prompt (sh#).
Here we are, we have gained root access to the filesystem, let’s finally change the password.
As root, changing password does not ask for your old password, therefore running the command:
# passwd
will prompt you for your new password and will ask you to confirm it to make sure there is no typo.
That’s it, you can now reboot your box and gain root access again.

Auto Mount Drives at System Startup on Ubuntu

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Ubuntu is capable of reading and writing files stored on Windows formatted partitions, but partitions must be ‘mounted’ before they can be accessed each time you start up the system. With these steps, you can auto mount the drives or partitions without the need to manually mount them for access.
Install Storage Device Manager if it has not been added.
– go to Applications (or Main Menu) > Ubuntu Software Center.
– enter pysdm in the Search Box.
– select Storage Device Manager, click the “Install” button.
– go to System > Administration > Storage Device Manager.
– extend the list of sda and select the sda you want to auto mount, click ‘OK’ to configure.
– click the “Assistant” button.
– uncheck “Mount file system in read only mode” and keep “The file system is mounted at boot time” checked.
– click the “Mount”, “Apply” then “Close” button, and restart the system.
In case you wish to remove the auto-mount of a certain drive or partition, you can similarly use Storage Device Manager to do the setting.

Note: If you need to identify disk partitions by label, paste ls /dev/disk/by-label -g in Terminal, or to view partition sizes and file systems, enter sudo fdisk -l. Disk Utility mentioned in “Name or Label a Partition” also gives you a glance of device numbers, partition types, sizes and labels.

Enable Windows 7 Aero Snap in Ubuntu

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In Windows 7, you can click and drag a window to the left or right edge of the desktop and it will fill half of the screen, or snap a window to the top edge of the desktop and it will be maximized.

In Ubuntu, you can click and drag a window to the left, right or top edge of the desktop to achieve the same result.

In addition to CompizConfig Settings Manager, install WmCtrl if not added:
– go to Applications (or Main Menu) > Accessories > Terminal.
– enter sudo apt-get install wmctrl
– enter password when prompted.
– go To System > Preferences > CompizConfig Settings Manager.
– select “General” from the left panel and click “Commands”.
In Command line 0, 1 and 2, paste the following codes:

Command line 0, paste:

WIDTH=`xdpyinfo | grep ‘dimensions:’ | cut -f 2 -d ‘:’ | cut -f 1 -d ‘x’` && HALF=$(($WIDTH/2)) && wmctrl -r :ACTIVE: -b add,maximized_vert && wmctrl -r :ACTIVE: -e 0,0,0,$HALF,-1

Command line 1, paste:

WIDTH=`xdpyinfo | grep ‘dimensions:’ | cut -f 2 -d ‘:’ | cut -f 1 -d ‘x’` && HALF=$(($WIDTH/2)) && wmctrl -r :ACTIVE: -b add,maximized_vert && wmctrl -r :ACTIVE: -e 0,$HALF,0,$HALF,-1

Command line 2, paste:

wmctrl -r :ACTIVE: -b add,maximized_vert,maximized_horz

In the same window, click “Edge Bindings” tab.
Change Run Command 0, 1 and 2 from “None” to “Left”, “Right” and “Top” respectively.
Click “Back” button and select “General Options”, change “Edge Trigger Delay” to about 500.