Install TP-LINK TL-WN821N v2 on Raspberry Pi

Download firmware like this:

# apt-get install firmware-linux-free

source:
https://wiki.debian.org/it/carl9170

then configure network:
http://www.bufferoverflow.it/2013/06/10/tp-link-tl-wn725n-nano-wifi-adapter-v2-0-e-raspberry-pi/

Linux: cannot set LC_CTYPE locale or related problems

To make it permanent just edit the file “/etc/environment” and add the line:

LC_ALL=C

or in

/etc/profile

add

export LC_ALL=C

Simple access SVN Subversion repository behind proxy

Uncommenting and set the following lines: 

[global]
http-proxy-host=my.proxy
http-proxy-port=80
http-proxy-username=[username]
http-proxy-password=[password]

in file
~/.subversion/servers

Simple essential TAR usage

create archive:

tar -cvf test.tar /home/test/

extract archive:

tar -xvf test.tar

list archive content:

tar -tvf test.tar