How to Check MD5Sum of Ubuntu ISO

It is very easy to check md5sum of ubuntu linux iso image. By checking the image before burning ensures that you have got the exact copy and you haven’t missed any byte during the download.

This check is useful especially if you’re burning the cds or DVDs which are not rewritable. If there is any checksum error then you can always download again from the torrent or other means which you prefer to download.

Let’s take example of Ubuntu 12.04 iso. We’re going to check the checksum value of the image in this tutorial.

Open the terminal and get into the directory where you have downloaded the iso file. If you have downloaded the iso in the downloads directory, type the command.

cd Downloads

Let’s check the md5sum of the downloaded iso.

md5sum ubuntu-12.04-desktop-i386.iso

If it returns the following then it is valid iso image.

d791352694374f1c478779f7f4447a3f

If you have downloaded any other ISO images other than i386 for 12.04 then compare it with below values.


9fcc322536575dda5879c279f0b142d7 *ubuntu-12.04-alternate-amd64.iso
bcee4c03b704a9b62988505b7d8f3069 *ubuntu-12.04-alternate-i386.iso
128f0c16f4734c420b0185a492d92e52 *ubuntu-12.04-desktop-amd64.iso
d791352694374f1c478779f7f4447a3f *ubuntu-12.04-desktop-i386.iso
f2e921788d35bbdf0336d05d228136eb *ubuntu-12.04-server-amd64.iso
32184a83c8b5e6031e1264e5c499bc03 *ubuntu-12.04-server-i386.iso
d4aa1eb1131bacd46317dad1afc59ff6 *ubuntu-12.04-wubi-amd64.tar.xz
33452f884d1017aadde0ec468b83264c *ubuntu-12.04-wubi-i386.tar.xz
9813c75c0ef631942b4c9f989588ab85 *wubi.exe

There are md5sum values of other versions of ubuntu distro as well. Just check the value in respective download directory or you can check the wiki page.

Unity Keyboard Shortcuts for Ubuntu 12.04

Unity keyboard shortcuts can increase your productivity if you learn to use it to your benefit. I know some of you are from the menu based design of KDE and Gnome2 so you may find it irritating at first.

But if you give it a try out of curiosity then surely you’re going to find it easy to use and in fact it will speed up your work.

Keyboard shortcuts are not just for power users, even the “point and click” users can benefit from their use. If you want to give it a try on your ubuntu 12.04 setup then, click on Windows key or super key on keyboard for a second and you’ll see all the keyboard shortcuts.

Check the following image for the keyboard shortcuts.

HUD in Ubuntu is quite an improvement, you’ll be able to do a lot of good things with it. Just try these shortcuts one per day and you’ll see a lot of changes in your usage. You may feel that typing the application names is quite hard at first, which is natural. Once you get used to the Linux then surely remembering Linux commands and the application names in HUD takes few seconds and in some cases you just have to type a letter or two.

How to Install MATE on Ubuntu

Mate is now a matured desktop environment and can easily co-exist with the gnome 3+ and unity. So now you can install it on ubuntu without any issues with any other window managers. In this tutorial I assume you know how to add the PPA in software center and install from the terminal.

Add the Mate repository with the following commands.

sudo add-apt-repository
"deb http://packages.mate-desktop.org/repo/ubuntu $(lsb_release -cs) main"
sudo apt-get update
sudo apt-get install mate-archive-keyring
sudo apt-get update
sudo apt-get install mate-core
sudo apt-get install mate-desktop-environment

Once you enter all these commands let the install take it’s time and once install you can reboot and then choose the Mate desktop environment during the login screen. New bugs are cleared everyday and the desktop is quite mature now. And in case if you get any error with your mate desktop, you can report the bug on their official forum. You can also send your fix in their github repository.
If you’re not satisfied with the results of the Mate desktop or you found a lot of bugs in  it and want to remove it. Use the following commands to remove the Mate desktop.

sudo apt-get remove atril atril-common caja caja-common engrampa engrampa-common
ffmpegthumbnailer-caja libcaja-extension libmarco libmate libmate-common libmatecanvas
libmatecomponent libmatecomponentui libmateconf libmatecorba libmatedesktop libmatekbd
libmatekeyring libmatemenu libmatenotify libmatepanelapplet libmatepolkit libmateui
libmatevfs libmateweather libmateweather-common marco marco-common mate-applets
mate-applets-common mate-backgrounds mate-conf mate-conf-common mate-control-center
mate-corba mate-core mate-desktop mate-desktop-common mate-dialogs mate-icon-theme
mate-keyring mate-media mate-menus mate-mime-data mate-panel mate-panel-common
mate-polkit mate-power-manager mate-power-manager-common mate-screensaver
mate-session-manager mate-settings-daemon mate-settings-daemon-common
mate-settings-daemon-gstreamer mate-system-monitor mate-terminal
mate-terminal-common mate-text-editor mate-themes mate-vfs
mate-vfs-common mate-window-manager python-mate

Also you can remove the remaining packages by running the following commands.

sudo apt-get remove libmatesensorsappletplugin mate-calc ate-desktop-environment mate-netspeed mate-sensors-applet mate-system-tools mate-utils mozo python-mate-menu system-tools-backends

As goal of mate is to preserve the traditional desktop which was discontinued by gnome after version 2. You can come back to it anytime and install.

Gnome Classic Install on Ubuntu 12.04

Gnome 2 classic interface was very powerful and easy to use for many users who got used to it during LTS 10.04 version of Ubuntu.

Now that many people are migrating from Ubuntu 10.04 to 12.04 LTS. It would be hard for them to use gnome 3 and unity desktop if they like “point and click” interface.

Gnome 3 and Unity with HUD forces you to type more  in order to open the applications and also to access the menus. It doesn’t stop here but it tries to make things more complicated by adding global menus on top-applet instead of keeping it sticked to particular application.

If you want to skip this UN-necessary and useless improvements and want to return to the old gnome classic interface then you need to install gnome panel.
Install gnome session fallback by entering following commands into the terminal.

sudo apt-get install gnome-session-fallback

You can also install the global appmenu (Appmenu) by entering the following commands in the terminal.

indicator-applet-appmenu

Once it is executed you can add more applets on the panel by hitting “[Win]+[Alt]+Right click” or “[ALT]+Right click” on panel.

Once installed you can logout from the current session and chooses the gnome-classic or gnome-classic(without effects) during the login. If you are low on hardware resource then it is better to run the gnome-classic without effects.

 

How to Solve : The following signatures couldn't be verified because the public key is not available: NO_PUBKEY

When you type in the apt-get update and get the NO_PUBKEY error then make sure that you copy the error number mentioned after the word NO_PUBKEY.

Once you copied that number you can use it along with following command to get gpg key from launchpad to fix that.

For example,

sudo apt-key adv --recv-keys --keyserver keyserver.ubuntu.com 61E5F6C15F6C1

Do execute the following command,

sudo-apt get update

as many times as the error occurs and then go ahead with the previous steps to import the GPG key. Once you get the errors resolved by importing the error key, you can do normal apt-get update.

Thats it, after importing the GPG for each error key, you can get the solution.

How to Switch Between Multiple Ruby Versions using Command Line

I am using ubuntu 12.04 and my machine got reset to the system version of ruby while installing the gem. I was not aware of how to switch between the versions. Here's how I figured out how to do that.

sudo update-alternatives --config ruby

sudo update-alternatives --config gem

You can first use rvm list and rvm use to check if you can switch between the versions that way and if it didn't worked then you can these commands in terminal. It works just fine and gets you the preferred version of ruby.