Skype Audio not working on Ubuntu

If you are having audio problems while using Skype on Ubuntu, first check to ensure that sound is working on your system and that your microphone and speaker volume levels are high enough. If you cannot hear yourself using the Skype Echo Sound Test, its possible that pavucontrol is not installed on your system. To install it, use the command :

sudo apt-get install pavucontrol

Restart Skype. Now the audio should work fine.

vmlinuz not found

While installing Ubuntu using a flash drive, you might get an error saying : /casper/vmlinuz not found. You cannot proceed with the installation until you correct it. To do this, you need to rename a file on the flash drive. You could log into another OS on your computer (if you have one) or use another computer.

1. On the flash drive, go to the directory vasper

2. Find a file named vmlinuz.efi

3. Rename that file to vmlinuz

4. Restart and boot using the flash drive. Now you'll be able to proceed with the installation. 

Changing computer name on Ubuntu

To change the computer name on Ubuntu, you need to do the following :

First, you need to edit /etc/hostname file. To do this, run the following command :

sudo vim /etc/hostname

Change the name as required. After that save and exit ( Use :x to save and exit).

Now, you need to edit /etc/hosts file. To do this, run the following command :

sudo vim /etc/hosts

In the file, you might see something like :

127.0.0.1       localhost

127.0.1.1       "your computer name"

Change the text next to 127.0.1.1 to the name you like. Save and exit.

To apply the changes, restart the hostname, and log out and log in again.

sudo service hostname restart

Ubuntu 13.10 crashes after Suspend

Firstly, make sure you have installed the proprietary drivers for your graphics card. For installing Nvidia drivers for Ubuntu, check out this post. If you continue to have problems even after this, then follow these steps.

sudo gedit /etc/default/grub

Find the line :

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

and replace it with :

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash pcie_aspm=force"

And run the command :

sudo update-grub

Creating multiple directories in Linux

For creating multiple directories, you can either specify the names using commas or you can specify a range.

mkdir file{1,2,3}

or

mkdir file{1..5}

Can't detect Android phone on Ubuntu 12.10

Apparently, this is a common problem in Ubuntu 12.04 and Ubuntu 12.10.

sudo add-apt-repository ppa:langdalepl/gvfs-mtp
sudo apt-get update

After running these commands, restart the system. After restart, your Android phone internal data storage will be listed in the devices automatically.

Hidden Directories in Linux

In Linux, directory (folder) names starting with a '.' are not visible to users. To view these files, you need to use the command :

ls -as

This command displays all the directories within the current directory. If you want to rename the directory. Suppose the name of the directory is direc. Then :

mv -i .direc direc

You will find that the hidden directory is now visible.

Installing Skype on Ubuntu

To install Skype on Ubuntu, follow these steps :

sudo add-apt-repository "deb http://archive.canonical.com/ $(lsb_release -sc) partner"
sudo apt-get update
sudo apt-get install skype

After the installation, type skype in the terminal to open it.

Installing Nvidia Drivers on Ubuntu

Without installing the display drivers, you will notice that the performance is the system is pretty poor, which becomes clearly visible while watching videos. So here's how you install the Nvidia drivers on Ubuntu :

sudo apt-get install build-essential linux-source linux-headers

After running this command, you might get an error saying : Package 'linux-headers' has no installation candidate. Ignore the error and continue to the next step.

sudo apt-get install linux-headers-`uname -r` 

sudo apt-get install nvidia-current 

Executing .run files in Linux

To be able to execute .run files, they first need to be converted to executable files. Use the command :

chmod +x [[filename]]

Then use the following command to execute :

./[[filename]]

Installing Adobe Flash Player on Kali Linux

To install Adobe Flash Player on Kali Linux, follow these steps :

1. Download Adobe Flash Player (.tar.gz) from http://get.adobe.com/flashplayer/ and save it in the root folder.

2. Now untar it using the command :

tar -xvzf [[name of the package]]

3. Change to directory usr/lib64/kde4 (if you are on a 64-bit machine) or usr/lib/kde4. Run the command :

cp kcm_adobe_flash_player.so /usr/lib/mozilla/plugins/

Error while installing Firefox on Kali Linux

I tried installing Firefox and got an error like this :

root@Hari:/home/harichandan# apt-get install firefox-mozilla-build
Reading package lists... Done
Building dependency tree       
Reading state information... Done
wine is already the newest version.
wine set to manually installed.
0 upgraded, 0 newly installed, 0 to remove and 0 not upgraded.
1 not fully installed or removed.
Need to get 0 B/29.7 MB of archives.
After this operation, 0 B of additional disk space will be used.
Do you want to continue [Y/n]? y
dpkg: error processing firefox-mozilla-build (--configure):
 package firefox-mozilla-build is not ready for configuration
 cannot configure (current status `half-installed')
Errors were encountered while processing:
 firefox-mozilla-build
E: Sub-process /usr/bin/dpkg returned an error code (1)

So to get around this, you just need to run the command :

apt-get install --reinstall firefox-mozilla-build

How to change ROOT password in Linux

Enter the command passwd.

Then choose the password you want!

Tap Clicking Not Working on Linux

This has happened quite a few time for me. No matter how much I fiddled with the system settings I couldn't get it working. There's a simple command which you need t run and it will work.

synclient tapbutton1=1 

Installing Aircrack-NG on Linux

Aircrack-ng is an 802.11 WEP and WPA-PSK keys cracking program that can recover keys once enough data packets have been captured. Fir installation, run the following commands :

sudo apt-get install build-essential

sudo apt-get install libssl-dev

wget http://download.aircrack-ng.org/aircrack-ng-1.1.tar.gz

tar -zxvf aircrack-ng-1.1.tar.gz

cd aircrack-ng-1.1

Edit the file common.mak before you run make and make install.

sudo gedit common.mak

Locate and change the unused variable werror. Change :

CFLAGS          ?= -g -W -Wall -Werror -O3

to

CFLAGS          ?= -g -W -Wall -O3

Now run :

sudo make
sudo make install 

After the installation, if you get a prompt as follows :

[*] Run 'airodump-ng-oui-update' as root (or with sudo) to install 
or update Airodump-ng OUI file (Internet connection required). 

Then run the command :

sudo airodump-ng-oui-update

Installing ettercap on Linux

Ettercap is a comprehensive suite for man in the middle attacks. It features sniffing of live connections, content filtering on the fly and many other interesting tricks. It supports active and passive dissection of many protocols and includes many features for network and host analysis.

For installing ettercap, use the following commands :

sudo apt-get install zlib1g zlib1g-dev
sudo apt-get install build-essential
sudo apt-get install ettercap

You will be prompted to choose between ettercap text-only and ettercap-graphical packages. Choose accordingly.

 

For installing ettercap-graphical, use the command :

sudo apt-get install ettercap-graphical

For installing ettercap-text only, use the command :

sudo apt-get install ettercap-text-only

 

After the installation is done, you can open ettercap in different modes. For opening ettercap in graphic mode, use :

sudo ettercap -G

For text mode, use

sudo ettercap -T

To read about ettercap and its different modes, you can use :

man ettercap

Note : 'man' is short for manual. It can be used to read about all commands (description, syntax etc.)

Capturing Packets using Wireshark

To start the capture of packets, select the interface from the left panel and click on Start.

Once you click on start, you'll notice that the capture of packets has begun and all the packets to and from your computer starts appearing.

 

If you just want to see a paticular type of packets, say ARP, HTTP etc., you can also add a filter. In the top left corner, type the desired type of packet. Only that type of packet will appear.

Cropping an image in Linux using GIMP

Cropping an image is a pretty basic feature in image editing software. Its pretty easy to do in Windows. You can even use Paint to do it in Windows. But I had a tough time doing it on Ubuntu. But its pretty easy to do it on GIMP. Here's how.

1. Open the image you want to crop on GIMP.

2. In the Toolbox, you have to look for the Crop Tool.

 

3. Use the Crop Tool to select the area you want to crop and click on the small rectangular box within the selected area to crop.

  4. You get the cropped image. Use Ctrl+S to save the image. Use Ctrl+Q to quit GIMP.

Installing MATLAB on Linux

I recently downloaded a MATLAB image to install on Linux thinking that it would be a walk in the park like Windows. But it wasn't. There a few things you need to take care of before installing MATLAB on Linux systems.

Firstly, you need to have Open JDK installed. I have read about people having problems installing MATLAB with Open JDK Java 7 (latest version). If you do, then  install Open JDK Java 6 and it should work fine.

In Windows you can just extract an ISO file and run the .exe file to install the software. But that doesn't work in Linux. First you need to mount the ISO. Ofcourse you can install some software for mounting with a GUI but I am going to tell you how to do it using commands.

To mount the ISO file, check this link here.

After mounting the ISO, enter the mounted drive using the following commands :

cd /mnt/disk

Now you can check the  files in this directory using ls command. You should find a file named install in the directory. Now use the commad :

./install

This should start the installation.

 

After the installation, you will be prompted to activate your software. Choose the option that suits you. Since I had the activation file, I chose the option Activate Manually without Internet. 

 

After activating the software, MATLAB is ready to use. Now you can unmount the ISO file. For help on unmounting an ISO file, click here.  

Mounting & Unmounting an ISO in Linux

Mounting an ISO

To mount an ISO in Linux, you need to follow these steps :

Firstly, you need to create a directory where you will be mounting the ISO. You can do so using the command :

sudo mkdir -p /mnt/disk

Next, we mount the ISO file using the command :

sudo mount -o loop [filename].iso /mnt/disk

If you get an error saying that loop is not up, first load the loop module and then repeat the mount command. To load the loop module, use the command :

sudo modprobe loop

Note that you can always use TAB key to auto-complete the filename. -o loop is used to denote the mounted ISO file is a loop device. A loop device is a pseudo-device which writes/reads from a file rather than a hardware.

Unmounting an ISO

To unmount an ISO file, use the command :

sudo umount /mnt/disk

Use the following command if you are getting an error :

sudo umount -f /mnt/disk

Note that it is 'umount' and not 'unmount'.