Set LC_ALL once and for all...

To get rid of the annoying messages in ubuntu complaining about things like


perl: warning: Setting locale failed.
perl: warning: Please check that your locale settings:
        LANGUAGE = (unset),
        LC_ALL = (unset),
        LC_CTYPE = "UTF-8",
        LANG = "en_US.UTF-8"
    are supported and installed on your system.
perl: warning: Falling back to the standard locale ("C").
locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory

you should do

sudo locale-gen en_US.UTF-8
sudo dpkg-reconfigure locales

Thanks to this thread http://ubuntuforums.org/showthread.php?t=1720356 !!!

Install tiny webserver on archlinux

# pacman -S darkhttpd
# mkdir /var/httpd
# chmod a+rx /var/httpd
# echo > /var/httpd/start-server.sh \
    'darkhttpd /var/httpd --log /var/log/httpd.log --uid daemon  --chroot --daemon'
# chmod 0700 /var/httpd/start-server.sh
# echo Hello > index.html
# chmod a+r index.html
# /var/httpd/start-server.sh

Multiple ipv6 addresses on an interface

To prevent being tracked on the intertubes, ipv6 has security extensions that, (if they are enabled via sysctl net.ipv6.conf.all somewhere), from time to time creates random a address, and expire the old ones for outgoing traffic. To see the addresses do

ip -6 addr

and look for temporary.  The expired addresses (that still work) have the word "deprecated".  If you get sick of seeing them, delete an address from an interface with

ip -6 addr del dev eth0

or delete all deprecated addresses like this

ip -6 addr | awk '/deprecated/ {print "ip -6 addr del " $2 " dev eth0"}' | sudo bash -s

Virtual X11 display

x11vnc -create -forever -localhost

-create launches Xvfb  (on DISPLAY=:20 or something like that)
-forever enables reconnection
-localhost only listens to local connections, so you'll have to forward the port (5900+nr) for instance over ssh.

Then one may need a windowmanager too, for instance

DISPLAY=:10 fluxbox

You may put fluxbox in the .xinitrc file too.

posting to xen-devel

example

git format-patch 73edc26b69803cdbce62513c7be8010c829e4274^..73edc26b69803cdbce62513c7be8010c829e4274

git send-email --in-reply-to '<1358428780 .13856.57.camel=".13856.57.camel" zakaz.uk.xensource.com="zakaz.uk.xensource.com">' --from lra@sics.se --to xen-devel@lists.xensource.com --smtp-server smtp.sics.se  0001-Set-register-values-and-comment-in-early-init_uart-t.patch

inplace quicksort in python

https://gist.github.com/4537928


def quicksort(l):
work = [(0,len(l)-1)]
while work:
(left,right) = work.pop()
if right < left: 
continue
i_piv = left
piv = l[i_piv]
l0,r0 = left, right
while left < right:
while l[left] <= piv and left < right: left += 1
while l[right] > piv: right -= 1
if left < right: l[left], l[right] = l[right], l[left]
l[i_piv], l[right] = l[right], piv
work.append((l0,right-1))
work.append((right+1,r0))

Python is_prime using Miller-Rabin

from random import randrange

def is_prime(n, trials=6):
    """ Miller-Rabin probabilistic prime test.
    """
    if n < 2:
        return False
    i = 0
    while i < trials:
        i+=1
        a = randrange(1, n)
        if pow(a, n-1, n) != 1: # (a**(n-1)) % n
            return False
    return True

# or as a tiny-font-one-liner


def is_prime(n, trials=6):
    return n >= 2 and (trials == 0 or (pow(randrange(1, n), n-1, n) == 1 and is_prime(n, trials - 1)))