How to remove icons from Top-Taskbar on Gnome

You are using the Gnome-Classic interface - either you are using this by choice, or you are using the fallback  mode which occurs if your graphics card & driver doesnt the 3D Acceleration required for the full Gnome-Shell GUI.

To add and remove application launchers in the gnome-panel you need to:

Press Win+Alt and right-click the top menu bar - N.B. Win is the Windows Symbol key

If you are not using Compiz then you need to :

Press Alt and right-click the top menu bar

Much more information is described in the linked Q&A and other links in that answer.

Linux Containers on Virtualbox - Disposal Boxes

Hey look, a month went by and I stopped blogging because I have a new job. Great. 
One of my responsibilities is keeping an eye on our sprawling Github account, currently at 326 repositories and 151 members. The current fellows are working on a huge number of projects and I frequently need to be able to quickly install, test and run projects with a weirdly-large variety of backend and server technologies. So, it’s become incredibly important to me to be able to rapidly spin up disposable Linux web servers to test with. Seth clued me in to Linux Containers (LXC) for this: 

LXC provides operating system-level virtualization not via a full blown virtual machine, but rather provides a virtual environment that has its own process and network space. LXC relies on the Linux kernel cgroups functionality that became available in version 2.6.24, developed as part of LXC. … It is used by Heroku to provide separation between their “dynos.”

I use a Mac, so I’m running these under Virtualbox. I move around between a number of different networks, so each server container had to have a no-hassle network connection. I’m also impatient, so I really needed to be able to clone these in seconds and have them ready to use. 
This is a guide for creating an Ubuntu Linux virtual machine under Virtualbox to host individual containers with simple two-way network connectivity. You’ll be able to clone a container with a single command, and connect to it using a simple <container>.local host name. 

The Linux Host

First, download an Ubuntu ISO. I try to stick to the long-term support releases, so I’m using Ubuntu 12.04 here. Get a copy of Virtualbox, also free. 
Create a new Virtualbox virtual machine to boot from the Ubuntu installation ISO. For a root volume, I selected the VDI format with a size of 32GB. The disk image will expand as it’s allocated, so it won’t take up all that space right away. I manually created three partitions on the volume: 

1. 4.0 GB ext4 primary.
2. 512 MB swap, matching RAM size. Could use more.
3. All remaining space btrfs, mounted at /var/lib/lxc.

Btrfs (B-tree file system, pronounced “Butter F S”, “Butterfuss”, “Better F S”, or “B-tree F S") is a GPL-licensed experimental copy-on-write file system. It will allow our cloned containers to occupy only as much disk space as is changed, which will decrease the overall file size of the virtual machine. 
During the OS installation process, you’ll need to select a host name. I used “ubuntu-demo” for this demonstration. 

Host Linux Networking

Boot into Linux. I started by installing some basics, for me: git, vim, tcsh, screen, htop, and etckeeper. 
Set up /etc/network/interfaces with two bridges for eth0 and eth1, both DHCP. Note that eth0 and eth1 must be commented-out, as in this sample part of my /etc/network/interfaces: 

## The primary network interface
#auto eth0
#iface eth0 inet dhcp

auto br0
iface br0 inet dhcp
        dns-nameservers 8.8.8.8
        bridge_ports eth0
        bridge_fd 0
        bridge_maxwait 0

auto br1
iface br1 inet dhcp
        bridge_ports eth1
        bridge_fd 0
        bridge_maxwait 0

Back in Virtualbox preferencese, create a new network adapter and call it “vboxnet0”. My settings are 10.1.0.1, 255.255.255.0, with DHCP turned on. 


Shut down the Linux host, and add the secondary interface in Virtual box. Choose host-only networking, the vboxnet0adapter, and “Allow All” promiscuous mode so that the containers can see inbound network traffic. 

The primary interface will be NAT by default, which will carry normal out-bound internet traffic. 

1. Adapter 1: NAT (default)
2. Adapter 2: Host-Only vboxnet0

Start up the Linux host again, and you should now be able to ping the outside world. 

% ping 8.8.8.8

PING 8.8.8.8 (8.8.8.8) 56(84) bytes of data.
64 bytes from 8.8.8.8: icmp_req=1 ttl=63 time=340 ms
…

Use ifconfig to find your Linux IP address (mine is 10.1.0.2), and try ssh’ing to that address from your Mac command line with the username you chose during initial Ubuntu installation. 

% ifconfig br1

br1       Link encap:Ethernet  HWaddr 08:00:27:94:df:ed  
          inet addr:10.1.0.2  Bcast:10.1.0.255  Mask:255.255.255.0
          inet6 addr: …

Next, we’ll set up Avahi to broadcast host names so we don’t need to remember DHCP-assigned IP addresses. On the Linux host, install avahi-daemon: 

% apt-get install avahi-daemon

In the configuration file /etc/avahi/avahi-daemon.conf, change these lines to clarify that our host names need only work on the second, host-only network adapter: 

allow-interfaces=br1,eth1
deny-interfaces=br0,eth0,lxcbr0

Then restart Avahi. 

% sudo service avahi-daemon restart

Now, you should be able to ping and ssh to ubuntu-demo.local from within the virtual machine and your Mac command line. 

No Guest Containers

So far, we have a Linux virtual machine with a reliable two-way network connection that’s resilient to external network failures, available via a meaningful host name, and with a slightly funny disk setup. You could stop here, skipping the LXC steps and use Virtualbox’s built-in cloning functionality or something like Vagrant to set up fresh development environments. I’m going to keep going and set up LXC. 

Linux Guest Containers

Install LXC. 

% sudo apt-get lxc

Initial LXC setup uses templates, and on Ubuntu there are several useful ones that come with the package. You can find them under /usr/lib/lxc/templates; I have templates for ubuntu, fedora, debian, opensuse, and other popular Linux distributions. To create a new container called “base” use lxc-create with a chosen template. 

% sudo lxc-create -n base -t ubuntu

This takes a few minutes, because it needs retrieve a bunch of packages for a minimal Ubuntu system. You’ll see this message at some point: 

##
# The default user is 'ubuntu' with password 'ubuntu'!
# Use the 'sudo' command to run tasks as root in the container.
##

Without starting the container, modify its network adapters to match the two we set up earlier. Edit the top of/var/lib/lxc/base/config to look something like this: 

lxc.network.type=veth
lxc.network.link=br0
lxc.network.flags=up
lxc.network.hwaddr = 00:16:3e:c2:9d:71

lxc.network.type=veth
lxc.network.link=br1
lxc.network.flags=up
lxc.network.hwaddr = 00:16:3e:c2:9d:72

An initial MAC address will be randomly generated for you under lxc.network.hwaddr, just make sure that the second one is different. 
Modify the container’s network interfaces by editing /var/lib/lxc/base/rootfs/etc/network/interfaces (/var/lib/lxc/base/rootfsis the root filesystem of the new container) to look like this: 

auto eth0
iface eth0 inet dhcp
        dns-nameservers 8.8.8.8

auto eth1
iface eth1 inet dhcp

Now your container knows about two network adapters, and they have been bridged to the Linux host OS virtual machine NAT and host-only adapters. Start your new container: 

% sudo lxc-start -n base

You’ll see a normal Linux login screen at first, use the default username and password “ubuntu” and “ubuntu” from above. The system starts out with minimal packages. Install a few so you can get around, and include language-pack-en so you don’t get a bunch of annoying character set warnings: 

% sudo apt-get install language-pack-en
% sudo apt-get install git vim tcsh screen htop etckeeper
% sudo apt-get install avahi-daemon

Make a similar change to the /etc/avahi/avahi-daemon.conf as above: 

allow-interfaces=eth1
deny-interfaces=eth0

Shut down to return to the Linux host OS. 

% sudo shutdown -h now

Now, restart the container with all the above modifications, in daemon mode. 

% sudo lxc-start -d -n base

After it’s started up, you should be able to ping and ssh to base.local from your Linux host OS and your Mac. 

% ssh ubuntu@base.local

Cloning a Container

Finally, we will clone the base container. If you’re curious about the effects of Btrfs, check the overall disk usage of the/var/lib/lxc volume where the containers are stored: 

% df -h /var/lib/lxc

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        28G  572M   26G   3% /var/lib/lxc

Clone the base container to a new one, called “clone”. 

% sudo lxc-clone  -o base -n clone

Look at the disk usage again, and you will see that it’s not grown by much. 

% df -h /var/lib/lxc

Filesystem      Size  Used Avail Use% Mounted on
/dev/sda3        28G  573M   26G   3% /var/lib/lxc

If you actually look at the disk usage of the individual container directories, you’ll see that Btrfs is allowing 1.1GB of files to live in just 573MB of space, representing the repeating base files between the two containers. 

% sudo du -sch /var/lib/lxc/*

560M /var/lib/lxc/base
560M /var/lib/lxc/clone
1.1G total

You can now start the new clone container, connect to it and begin making changes. 

% sudo lxc-start -d -n clone
% ssh ubuntu@clone.local

Conclusion

I have been using this setup for the past few weeks, currently with a half-dozen containers that I use for a variety of jobs: testing TileStache, installing Rails applications with RVM, serving Postgres data, and checking out new packages. One drawback that I have encountered is that as the disk image grows, my nightly time machine backups grow considerably. The Mac host OS can only see the Linux disk image as a single file. 
On the other hand, having ready access to a variety of local Linux environments has been a boon to my ability to quickly try out ideas. Special thanks again to Seth for helping me work through some of the networking ugliness. 

Further Reading

Tao of Mac has an article on a similar, but slightly different Virtualbox and LXC setup. They don’t include the promiscuous mode setting for the second network adapter, which I think is why they advise using Avahi and port forwarding to connect to the machine. I believe my way here might be easier. 
Shift describes a Vagrant and LXC setup that skips Avahi and uses a plain hostnames for internal connectivity.

The Owner of this post is Michal Migurski
Find is Blog here http://mike.teczno.com/notes/disposable-virtualbox-lxc-environments.html 

How to Install vsftpd on Ubuntu and Add New User

Warning: FTP is inherently insecure. If you must use FTP, consider securing your FTP connection with SSL/TLS. Otherwise, it is best to use SFTP, a secure alternative to FTP.

The first two letters of vsftpd stand for "very secure" and the program was built to have strongest protection against possible FTP vulnerabilities.

Step One—Install vsftpd

You can quickly install vsftpd on your virtual private server in the command line:

sudo apt-get install vsftpd

Once the file finishes downloading, the VSFTP will be on your droplet. Generally speaking, it is already configured with a reasonable amount of security. However, it does provide access on your VPS to anonymous users.

Step Two—Configure vsftpd

Once vsftpd is installed, you can adjust the configuration.

Open up the configuration file:

sudo nano /etc/vsftpd.conf

The biggest change you need to make is to switch the Anonymous_enable from YES to NO:

anonymous_enable=NO

Prior to this change, vsftpd allowed anonymous, unidentified users to access the server's files. This is useful if you are seeking to distribute information widely, but may be considered a serious security issue in most other cases.

After that, uncomment the local_enable option, changing it to yes and, additionally, allow the user to write to the directory.

local_enable=YES

write_enable=YES

Finish up by uncommenting command to chroot_local_user. When this line is set to Yes, all the local users will be jailed within their chroot and will be denied access to any other part of the server.

chroot_local_user=YES

Save and Exit that file.

Because of a recent vsftpd upgrade, vsftpd is "refusing to run with writable root inside chroot". A handy way to address this issue to is to take the following steps:

Create a new directory within the user's home directory

mkdir /home/username/files

Change the ownership of that file to root

chown root:root /home/username

Make all necessary changes within the "files" subdirectory

Then, as always, restart:

sudo service vsftpd restart

Step Three—Access the FTP server

Once you have installed the FTP server and configured it to your liking, you can now access it.

You can reach an FTP server in the browser by typing the domain name into the address bar and logging in with the appropriate ID. Keep in mind, you will only be able to access the user's home directory.

ftp://example.com

Alternatively, you can reach the FTP server on your virtual server through the command line by typing:

ftp example.com

Then you can use the word, "exit," to get out of the FTP shell.

Adding New Users To vsftpd

I found it rather strange that there arent any good tutorial that can explain how to add new users to vftpd. Google gives few results but most of them are trial and error method. So i decided to write this post after spending 1 hr trying to accomplish this simple task.

#edit /etc/vsftpd.conf or /opt/etc/vsftpd.conf
Open the vsftpd.conf file and search for chroot_list_enable=YES
Make sure it is YES. Do the same for the following variables
chroot_list_file=/etc/vsftpd.chroot_list or /opt/etc/vsftpd.chroot_list
chroot_list_enable=YES
Save and close the file

Create vsftpd.chroot_list in /etc/ or /opt/etc/
Add the username you want to export to ftp.
IMP: The user must already be a system user with a valid passwd. You must be able to find /home/
If the user you want to add is not a system user then create that user first before editing the above file.
#adduser 
#passwd 

Restart the vsftpd server using /etc/init.d/vsftpd restart or service vsftpd restart
Now you can log into ftp using the new user.

How do You Install XvidCap on uBuntu 12.04 Distro

Xvidcap is a small tool to capture things going on on an X-Windows display to either individual frames or an MPEG video. This software is not present in the Ubuntu 12.04 repository by default. You can get a copy of the distributed binary in the form of a .deb package at the following link.

https://launchpad.net/ubuntu/precise/amd64/xvidcap/

Once you download this package, go ahead and install the package with the following command. The amd64 package given as example is for 64 bit machine.

$ sudo dpkg -i xvidcap_1.1.7-0.2ubuntu12_amd64

In case if the above command fails giving out errors, please note that Xvidcap depends on libavdevice-extra-53 package. So go ahead and install this package first with the following command.

$ sudo  apt-get install libavdevice-extra-53

By default, the Ubuntu 12.04 comes with libavcodec53 package. This conflicts with the  libavdevice-extra-53. In such a case, feel free to go ahead and replace the libavcodec53 package with libavdevice-extra-53. This satisfies the dependency requirement for Xvidcap.

Once done with setting dependencies, you can then install the Xvidcap package.

How To Find & Remove Duplicate Files In Windows/Mac PC

Method 1. Use Anti-Twin Software (for Windows, Linux and Mac).

Anti-Twin is one the popular tool to remove duplicate files from PC. It is available for Windows, Linux, Mac. One of its major advantage is that it is freely available for users. It can compare duplicate files for images, music, videos, text, software etc. It provide easy to use interface. To know the step by step procedure for comparing files read following steps.

Step 1. Download and install Anti-Twin by clicking the button below.

Step 2. Now launch the software and select the source and destination folder for comparing the files.

Step 3. You can also use the filter option for minimum and maximum file size, for specific type of file etc.

Step 4. After that we have to select a comparison method for comparing file like byte by byte comparison, name comparison and many others.

Step 5. We can also compare different images, software and many other types of similar files.

Step 6. Now click on the search for duplicates files button and program start for comparing files.

Method 2:- Using Easy Duplicate Finder (For Windows, MAC ).

Easy Duplicate file finder is one of the best tools for finding and also to remove duplicate files in windows and mac. It is available for both Windows and MAC operating system. It has ability to compare Duplicate mp 3, images, text, software, emails, videos files. It can free your hard disk space in GB’s by removing Duplicate files. It require only 128 MB RAM, 5 MB space for its installation. It provide drag and drop capabilities for comparing files. It compare files byte by byte to find Duplicate files. It provide 100 % accuracy. We can compare files, folder and also hard drives for duplicate files. It is easy to operate and steps is almost similar like steps given above.

For downloading this tool click on the button below.

Method 3:- Using Duplicate Cleaner.

Duplicate cleaner is another popular tool for finding and removing Duplicate files and is available for both Windows and MAC. It is available for Windows XP, Visita, 7, 8, 10. It provide easy to use interface with attractive look. It can compare Duplicate files for Music, images, videos, text etc. It also provide Duplicate directories with same name. We can tick which directories we want to keep or not. We can also make our search smaller by giving the type of files which we want to compare. We can also compare files by date also. It also compare files byte by byte also we can compare files by name also. It is an all in one solution for duplicate files. You can download this tool by clicking the button below.

Method 4:- File Duplicate Files By Using Dupeguru.

Dupeguru is an open source tool for comparing Duplicate files. It is available in three different edition i.e dupeguru, dupeguru music, picture edition. Dupeguru edition can find identical files only for music, text, images etc. But dupeguru music edition can find similar music file at different bit rate. Dupeguru picture edition can find the similar images even they are of different size, re-size, crop etc. It is an easy to use software. It is freely available for users.

Method  5:- Visipics Duplicate Files Finder.

Visipics is specially designed for finding Duplicate pictures and also for similar, identical in type. If you have a large collection of pictures and you are enable to find Duplicate images then Visipics is best solution for you. It can find similar images if they are re-sized, crop. It can also find then even if they are compress in size. It provide an easy to interface. It is available for Windows XP, VISTA, 7,8.

So these are few best software to find and remove duplicates files from windows and mac devices. So if you have any of the best tool them must share it with us.