Add public key behind a firewall in Ubuntu Shell

In short: Use
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80/ --recv-key E084DAB9
instead of
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key E084DAB9
This way you force port 80 which is usually clear.

I got the idea from the answer of Phil Bradley on the superuser.com forum. He claimed that this would be fixed in Natty, but it isn’t although the configuration file he mentions has the port80 specification added by default, apt-key does not use it. The above snippet solves that.

For those Ubuntu users who have no idea what I am talking about:

Installing the newest R-version in Ubuntu requires to append the CRAN repository to you /etc/apt/sources.list. One might hit Alt+F2 and enter
gksu gedit /etc/apt/sources.list

With Xubuntu you would use mousepad instead of gedit. In any distro you can use
sudo nano /etc/apt/sources.list
in a terminal.

Usually I add the line
deb http://cran.uib.no/bin/linux/ubuntu natty/
at the end of the file and update with
sudo apt-get update.

CRAN at University of Bergen is closest to me. You might want another one (check the r-project.org site for mirrors).

apt-get update answers with a warning
GPG error: http://cran.uib.no nat/ Release: The folowing signatures coldn't be verified because the public key is not abailable

That is not a problem. One can install R and packages anyway, but it is better to have the public key.

Behind a firewall (and many public and open hotspots block several ports) it is not possible to use

sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-key E084DAB9

since the port through which the keyserver is contacted is blocked on most firewalls. You have to force port 80 by:
sudo apt-key adv --keyserver hkp://keyserver.ubuntu.com:80/ --recv-key E084DAB9

After the key is added
sudo apt-get update
sudo apt-get install R-recommended emacs ess

proceeds without warning nor error.

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Setup FTP on Amazon EC2

If your Amazon EC2 instance is finally running – which is another story – one would want to have ftp access to upload files and documents.

I got the inspiration to use vsftpd from curiousdeveloper.blogspot.com

  1. Open port 21 for ftp access on you running instances:
    ec2-authorize default -p 21
  2. Connect to your instance via ssh
    ip=`ec2din | grep I | cut -f17`
    ssh -i /path/to/yourkey.pem ubuntu@$ip
  3. Install vsftpd
    sudo aptitude install vsftpd
  4. Start the demon
    sudo /etc/init.d/vsftpd start

Using gammu to connect to a mobile phone

After switching between mobile phones several times I always lost some data, contacts, media, so on…

There is a Linux tool called Gammu which allows to connect a selection of mobile phones. It seems that Gammus functionality is maximal for Nokia and Siemens, but I will give it a try on my Sony Ericsson…

The configuration is not trivial and I found some hints on JohnMcClumpha.org:

Install Gammu

Installing gammu is surprisingly easy (once again thanks to the wonders of apt-get), just use the following command:

sudo apt-get install gammu

Hard wasn’t it? 😉

OK now it’s time to plug your phone in and see if we can get things talking. With the phone connected, type the following command:

lsusb

you should now see your phone listed as a device – for example:

Bus 001 Device 002: ID 0421:0802 Nokia Mobile Phones

if not – make sure your cables and power are all good and try again.

The gammu installation comes with some example configuration files which are worth using as a starting point – if nothing else they help you to understand how gammu can be configured so that you can tailor a solution for your needs. These are located in
/usr/share/doc/gammu/examples
(in gZip archives).

Copy the gammurc file to /etc/gammurc :

sudo cp /usr/share/doc/gammu/examples/config/gammurc /etc/gammurc

Now edit /etc/gammurc to specify your port and connection type (this will vary based upon where/how you have things plugged in and what sort of cable/interface your phone is using). The settings for mine are:

port = /dev/ttyACM0
connection = dku5

Save this config and from the shell type:

gammu --identify

you should now be presented with some information regaqrding your phone such as:

Manufacturer : Nokia
Model : 7200 (RH-23)
Firmware : 3.110 T (18-03-04)
Hardware : 0903
IMEI : 353363000813894
Original IMEI : 353363/00/081389/4
Manufactured : 04/2004
Product code : 0514143
UEM : 16

If this is the case then you have got gammu up and running and can send yourself a test message with the following command:

 echo "boo" | gammu --sendsms TEXT [recipient mobile number]

Restructuring the filetree – moving files from multiple directories

I am considering changing the structure of my /home directory, maybe completely changing my data organisation habbits.

I found this post on ubuntuforums very useful:

You need to use find

For this example I`m going to assume that all the .txt files are located in directories and subdirectories of your Documents folder and you want to move them to a directory in your home called scripts
Code:
find ~/Documents -name '*.txt' -exec mv '{}' ~/scripts \;

Remove U3 System from SanDisk

Bought a SanDisk Cruzer 16GB and found some smart software preinstalled which did not consider smart at all. Everytime I inserted the drive on any computer a CD drive with label U3 System“was mounted containing some funny .exe files. The whole “CD drive” took several MB of diskspace.

I wanted to get rid of it. Fortunately, I was not the first one beeing disturbed.

Sourceforge has a u3-tool which did the job:

  1. Download the tool to a place where you remember it
  2. Unpack the .tar.gz archive (I just rightclicked it and chose “extract here”). This creates a folder like /MyPathTo/u3-tool-0.3/
  3. open a terminal and type: cd /MyPathTo/u3-tool-0.3/
    ./configure
    make
    sudo make install

    Now u3-tool is installed and can be used.
  4. To remove the CD-like partition containing the firmware crap you need the device name of the USB disk: sudo fdisk -l gives the answer. In my case it is /dev/sdb1. Make shure you remember the right one.
  5. Remove the U3 partition with u3-tool -p 0 /dev/sdb1where /dev/sdb1 is the device name remembered from the previous step and the option -p is followed by a zero.

Done.

Passing an external variable to AWK

Confronted with a heap of colon separated text files which had to be merged and cleaned of unrelated lines and columns, i tryed my luck inside Excel and spend a lot of time doing it manually, but finally got fed up.

So I decided to use AWK on the task.

A FOR-loop lists the files in the folder into the UNIX pipe.

AWK selects the non-empty observations and adds the name of the file as a classifier to the beginning of the line (the result is a repeated measure dataset).

This is the code:

for CSV in `ls`
do
cat $CSV | awk -F ";" '{
if ($2 ~ /[0-9]+/) {print CSV , FS , $0;}}'
done

Remark: -F ";" option specifies how to distinguish the columns/fields of the lines/records in the file(default is ” ” or empty space).

BUT: The variable CSV gets not passed to AWK by default it has to be fed into AWK.

Solution:
The
-v CATEGORY=$CSV
option feeds the external variable CSV into the AWK-variable CATEGORY.

This gives:
for CSV in `ls`
do
cat $CSV | awk -F ";" -v CATEGORY=$CSV '{
if ($2 ~ /[0-9]+/) {print CATEGORY , FS , $0;}}'
done

.. and works 🙂

Hat tip:fpmurphy