How to download an MP3 track from a YouTube video

Install youtube-dl from the official repository in Ubuntu:

sudo apt-get install youtube-dl

To download a video execute the following:

youtube-dl <url>

E.g

youtube-dl http://www.youtube.com/watch?v=_z-hEyVQDRA

You can also specify other options

-b            Best quality
-m            Mobile version
-d            High Definition
-g            Don’t download, just show the url
-c            Resume download of a video which was interrupted before
-w            Don’t overwrite existing file

For complete list of switches execute man youtube-dl in terminal.

Information from http://www.absolutelytech.com/2010/06/26/howto-download-youtube-video-from-command-line-ubuntu/
Converting to mp3

Now install ffmpeg from the official repo.

sudo apt-get install ffmpeg

Next have a look to make sure the flv file has downloaded from youtube by typing

ls *flv

This will list all the flv files you have. What you should see is a flv file with the same name as the 'v' component of the youtube url you downloaded.

E.g if you downloaded http://www.youtube.com/watch?v=_z-hEyVQDRA then you should have a file called _z-hEyVQDRA.flv

Next you need to copy that file name and then put it in an ffmpg command like

ffmpeg -i <file name>.flv -acodec liblamemp3 <song name>.mp3

So for this example you would type

ffmpeg -i _z-hEyVQDRA.flv -acodec liblamemp3 MasterOfPuppets.mp3

Once this has successfully completed you will now have the mp3 file you were after.

Note For cleanup you may want to type rm _z-hEyVQDRA.flv to get rid of the flv file that you no longer need.



You can also download the mp3 directly from youtube without converting using ffmpeg

youtube-dl --extract-audio --audio-format mp3 <video URL>

Playlist

youtube-dl -cit --max-quality FORMAT --extract-audio --audio-format mp3 http://www.youtube.com/playlist?list=XXXXXXXXXXX

From the online help:

-x, --extract-audio        convert video files to audio-only files (requires
                           ffmpeg or avconv and ffprobe or avprobe)

Bear in mind as well that youtube-dl defaults to using avconv so you should consider specifying either avconv or FFmpeg at the commandline. From the online help:

--prefer-avconv                  Prefer avconv over ffmpeg for running the
                                 postprocessors (default)
--prefer-ffmpeg                  Prefer ffmpeg over avconv for running the
                                 postprocessors

Further options for keeping the original video, adjusting the bitrate or quality of the audio and a few others can be seen by looking at youtube -h.


https://github.com/rg3/youtube-dl

Clean up your Linux computer

No matter how careful or fastidious you are, over time a lot of cruft builds up on your computer. Things like cached files, cookies, temporary files, packages, log files, and a whole lot more. All of this builds up and takes up a tens or hundreds of megabytes of disk space.

BleachBit for Linux

BleachBit has many useful features designed to help you easily clean your computer to free space and maintain privacy.

http://bleachbit.sourceforge.net/


Ubuntu Tweak

Ubuntu Tweak is an application to config Ubuntu easier for everyone.  It provides many useful desktop and system options that the default desktop environment doesn't provide.  With its help, you will enjoy with the experience of Ubuntu!

http://ubuntu-tweak.com/

Server and Hosting Management

Ajenti is a server administration panel for Linux distributions and FreeBSD. It is similar to cPanel, ISPConfig and others like them, but kinda light in features. It is a Free Software application whose development is spear-headed by Eugene Pankov.Besides being a server administration panel, Ajenti may also be used by developers as a rapid-development platform to create Web frontends, and by hardware vendors to create Web interfaces.
http://ajenti.org


Virtualmin is a powerful and flexible web hosting control panel for Linux and UNIX systems based on the well-known Open Source web-based systems management GUI, Webmin. Manage your virtual domains, mailboxes, databases, applications, and the entire server, from one comprehensive and friendly interface. http://www.virtualmin.com/

Setting up a Wifi Hotspot on Ubuntu

The first thing I wanted to do after installing Ubuntu 12.04 is setup a wifi hotspot. I have a Samsung Netbook N130. I use a usb-modem to connect to the internet. I have a single data contract with Vodacom and I want all my devices to use this data at the same time.

Gathering information:

Opening a terminal and typing the following command :
#lspci
Showed me that I have a :
 Network controller: Atheros Communications Inc. AR9285 Wireless Network Adapter (PCI-Express)
#lsmod
Shows that it uses the ath9k drivers (this information may help you to google for setup information specific to your machine.)
Also
#iwconfig
will give you the name of your wireless adapter name for example:
“wlan0 “or “wlan1” (note that the “0″ and “1″ are numbers not letters)

Installing Programs

I then installed 2 programs via apt. In a terminal enter the following command:
#sudo apt-get install dhcp3-server
#sudo apt-get install hostapd

Editing Configuration Files

In a terminal:
#sudo gedit
This will bring up the editor with root privileges so that you can edit system files. (WARNING – editing system files can damage your system. Please do not edit system files unless you have made a backup of them first)
Open / Create the following files editing:
1. /etc/hostapd/hostapd.conf
interface=wlan0
driver=nl80211
ssid=my_hotspot
channel=1
hw_mode=g
auth_algs=1
wpa=3
wpa_passphrase=1234567890
wpa_key_mgmt=WPA-PSK
wpa_pairwise=TKIP CCMP
rsn_pairwise=CCMP
Please note: the “ssid” in this case “my_hotspot” is the name of the network that will show up on the device or laptop that will connect to the hotspot. The passphrase is a password – you can change this to any other 10 digit number. The device / laptop that wants to connect will have to enter this password.
Save the file.
2. /etc/default/isc-dhcp-server
Edit the line that says
INTERFACES=”"
To
INTERFACES=”wlan0″
Or change the “wlan0″ to “wlan1″ or whatever the wireless adapter name you have (see above section on gathering information.)
3. /etc/dhcp/dhcpd.conf
Make sure the follow lines are Commented out ( put a hash “#”  sign at the beginning of the line ) the following lines:
# option definitions common to all supported networks…
#option domain-name “example.org”;
#option domain-name-servers ns1.example.org, ns2.example.org;
#default-lease-time 600;
#max-lease-time 7200;
Add the following lines to the file (copy and paste)
subnet 10.10.0.0 netmask 255.255.255.0 {
        range 10.10.0.2 10.10.0.16;
        option domain-name-servers 8.8.4.4, 208.67.222.222;
        option routers 10.10.0.1;
}
(Note: the only other line in this whole config file that is uncommented is :
ddns-update-style none;)
4. /etc/default/hostapd
Add the following lines to the bottom of the file. Make sure similar lines are commented.
RUN_DAEMON=”yes”
DAEMON_CONF=”/etc/hostapd/hostapd.conf”
DAEMON_OPTS=”-dd”
(Note: This file makes sure hostapd program starts on bootup with your edited configuration files loaded)
5. /etc/network/interfaces
This is how my interfaces file looks:
auto lo
iface lo inet loopback
auto wlan0
iface wlan0 inet static
 address 10.10.0.1
 netmask 255.255.255.0
(Note: Again you must change every “wlan0″ to the name of your adapter. This file may have more entries for other network adapters. Just make sure you edit the section of the wireless adapter you want to use. This file will automatically configure the wireless network adapter’s network address at bootup time.)
At this stage you can reboot. And hopefully any device / laptop should connect to your wifi hotspots network via the network manager applet. On these devices search for the network “my_hotspot” and type in the password.
At this stage however you cannot access the Internet. Which brings us to another important step:

Internet connection Sharing.

You will need to ask yourself the following information. How do I connect to the internet on my ubuntu computer / laptop? In my case I use a usb 3G modem. You need to know the name of the network adapter that you connect to the internet on. > This must be different from the network adapter you configured above. (ie wlan0)
Connect to the internet, and in a terminal type:
#ifconfig
On my netbook, one of the entries is for adapter “ppp0″ this is the network adapter for my usb modem and the connection to the internet. The following steps use “ppp0″ however you can swap it for your adapter name:
To share the internet connection we have to do a thing called “ip masquerading”.
First we have to allow ip forwarding:
#sudo gedit
edit /etc/sysctl.conf
Make sure the following line is uncommented and reads
net.ipv4.ip_forward=1
Save and close gedit. (reboot)
After reboot: Connect to the Internet and In a terminal type:
# sudo iptables -t nat -A POSTROUTING -s 10.10.0.0/16 -o ppp0 -j MASQUERADE
(Note the “ppp0″ adapter name in the above line. The 10.10.0.0 is the ip address of your network that you configured in steps 3 and 5 above. Your wifi hotspot will thus share the internet with up to 15 machines that are given the ip addresses 10.10.0.2 to 10.10.0.16)
All devices and laptops should now be able to browse the internet and download email. If this works we have to make this permanent:
#sudo gedit
edit /etc/rc.local
add this line just before “exit 0″
iptables -t nat -A POSTROUTING -s 10.10.0.0/16 -o ppp0 -j MASQUERADE
Reboot / Connect to the internet and Enjoy your wifi hotspot.

Acknowledgements

When configuring and setting up mine I used and adapted the following  Howto’s and forums:
http://exain.wordpress.com/2011/03/31/making-a-wifi-hotspot-access-point-using-linux-wifi-lan-cardusb-adapter/
http://ubuntuforums.org/showthread.php?p=11890695#post11890695
http://ubuntuforums.org/showthread.php?p=11890408#post11890408


Source: https://thenewbieblog.wordpress.com/2012/05/01/wifi-hotspot-setup-on-ubuntu

Recovering grub after installing windows 7 on Ubuntu

To recover grub:

1. open the live version
2. open the terminal and run sudo fdisk -l to see where Linux is installed
3. run sudo mount /dev/sdaX /mnt where x is the number you have found Linux word in
4. run sudo grub-install --root-directory=/mnt /dev/sda to install grub
5. run sudo update-grub to update grub and if this command didn't work run it after rebooting
6. reboot

http://askubuntu.com/questions/83771/recovering-grub-after-installing-windows-7

How to add https to localhost

Use a Self-Signed SSL Certificate with Apache
These instructions will help you generate a generic self-signed certificate, which may be used to provide SSL service for all name-based hosts on your VPS. Please note that self-signed certificates will generate warnings in a visitor's browser; proceed to "Installing a Commercial SSL Certificate" if you need to set up SSL on a domain using a certificate signed by a commercial SSL provider.

Generate a Self-Signed Certificate
At the shell prompt, issue the following commands to enable SSL for Apache and generate a certificate:

a2enmod ssl mkdir /etc/apache2/ssl openssl req -new -x509 -days 365 -nodes -out /etc/apache2/ssl/apache.pem -keyout /etc/apache2/ssl/apache.key

You will be asked for several configuration values. Enter values appropriate for your organization and server, as shown here. This example will create a certificate valid for 365 days; you may wish to increase this value. We've specified the FQDN (fully qualified domain name) of the VPS for the "Common Name" entry, as this certificate will be used for generic SSL service.

Generating a 1024 bit RSA private key ...................................++++++ ..............................++++++ writing new private key to '/etc/apache2/ssl/apache.pem' ----- You are about to be asked to enter information that will be incorporated into your certificate request. What you are about to enter is what is called a Distinguished Name or a DN. There are quite a few fields but you can leave some blank For some fields there will be a default value, If you enter '.', the field will be left blank. ----- Country Name (2 letter code) [AU]:US State or Province Name (full name) [Some-State]:New Jersey Locality Name (eg, city) []:Absecon Organization Name (eg, company) [Internet Widgits Pty Ltd]:SoftwareDev, LLC Organizational Unit Name (eg, section) []:Web Services Common Name (eg, YOUR name) []:archimedes.mydomain.com Email Address []:support@mydomain.com

Configure Apache to use the Self-Signed Certificate
Since SSL name-based virtual hosts are still not supported in /etc/apache2/ports.conf, we'll need to add an entry for a specific IP address on your VPS as follows. You may use a single IP to provide self-signed SSL service for multiple vhosts, and the same IP may also be used for multiple non-SSL vhosts (HTTPS uses port 443, while HTTP uses port 80).

File excerpt:/etc/apache2/ports.conf

NameVirtualHost 12.34.56.78:443

Replace "12.34.56.78" with your Linode's IP address. Next, edit the virtual host configuration files for sites which you would like to enable SSL on. For each virtual host, you must add the following stanza (change the values as appropriate for each site). Note that this example essentially reproduces the configuration for a non-SSL site, with the addition of three lines for SSL.

File excerpt:Apache virtual hosting file

<VirtualHost 12.34.56.78:443> SSLEngine On SSLCertificateFile /etc/apache2/ssl/apache.pem SSLCertificateKeyFile /etc/apache2/ssl/apache.key ServerAdmin info@mydomain.com ServerName www.mydomain.com DocumentRoot /var/www/mydomain.com/public_html/ ErrorLog /var/www/mydomain.com/logs/error.log CustomLog /var/www/mydomain.com/logs/access.log combined </VirtualHost>

Restart Apache:

service apache2 restart

You should now be able to visit your site with SSL enabled (after accepting your browser's warnings about the certificate).

 
http://library.linode.com/web-servers/apache/ssl-guides

https://www.digitalocean.com/community/articles/how-to-create-a-ssl-certificate-on-apache-for-ubuntu-12-04

http://askubuntu.com/questions/49196/how-do-i-create-a-self-signed-ssl-certificate

http://ubuntuforums.org/showthread.php?t=953607



Virtual hosts overlap on 443, first has precedence

sudo gedit /etc/apache2/ports.conf

Change it to
 
<IfModule mod_ssl.c>
NameVirtualHost *:443
Listen 443
</IfModule>

http://blog.breidert.net/virtual-hosts-overlap-443-first-has-precendence/

apt-get update fails to fetch files,"Temporary failure resolving …" error

overview

There are two parts to your question:

• fixing temporary resolve messages
• fixing the package management issues

Temporary resolve

It is likely that this issue is either:

• temporary due to your Internet Service Provider not correctly forwarding internet naming (DNS) to either its or external DNS servers, or
• due to a change in your network has similarly blocked this naming - for example, new router/modem, reconfiguring a switch with a new configuration.

Lets look at the possible DNS resolving issues.

First, temporarily add a known DNS server to your system.

echo "nameserver 8.8.8.8" | sudo tee /etc/resolv.conf > /dev/null

Then run sudo apt-get update.

If this fixes your temporary resolving messages then either wait for 24 hours to see if your ISP fixes the issue for you (or just contact your ISP) - or you can permanently add a DNS server to your system:

echo "nameserver 8.8.8.8" | sudo tee /etc/resolvconf/resolv.conf.d/base > /dev/null

8.8.8.8 is Google's own DNS server.

source

Another example DNS server you could use is OpenDNS - for example:

echo "nameserver 208.67.222.222" | sudo tee /etc/resolvconf/resolv.conf.d/base > /dev/null

package-management issues

In addition to the temporary resolve issues - you have a few package management issues that need to be corrected - I'm assuming you have tried recently to upgrade from one Ubuntu version to the next recommended version - in your case from Natty (11.04) to Oneiric (11.10)

Open a terminal and type

sudo nano /etc/apt/sources.list

Look for lines that have your a different distribution name in the list than you were expecting - in your case - you have upgraded to oneiric but you have another release name natty

For example, look for lines that look like deb http:/archive.canonical.com/ natty backports

Add a # to the beginning of the line to comment it out - for example

#deb http:/archive.canonical.com/ natty backports

Save and re-run:

sudo apt-get update && sudo apt-get upgrade

You should not have any more release naming errors.

 At the time of writing this, possible common release names include lucid, maverick, natty,oneiric, precise and quantal

http://askubuntu.com/questions/91543/apt-get-update-fails-to-fetch-files-temporary-failure-resolving-error