Linux and Programming Tips, Tricks, Hacks, Guides, and How-Tos » Uncategorized

An interesting bit of math

sean — Tue, 07 Jun 2011 08:38:28 +0000

http://plus.maths.org/content/os/issue26/features/sautoy/index

Every time you use your credit card on the internet to buy a ticket to see Real Madrid play, your account is kept secret from hackers thanks to the power of prime numbers. Prime numbers have become the locks that preserve the secrets that are racing through the electronic shopping mall.
Each e-business chooses two big primes, p and q, which they keep secret. The product of these primes, N=pxq, is made public. A calculation using N encrypts your credit card, but the only way to undo the calculation and decrypt the secret message is to know the secret primes p and q. Cracking codes is the same as cracking the public number N into its prime building blocks. It’s a bit like a chemist who wants to know the atoms inside a compound. Although chemists have solved their problem, mathematicians lack any fast way to do this prime-number spectroscopy – to the relief of internet cryptographers.

Quick list of words I misspell

sean — Fri, 27 May 2011 01:40:29 +0000

I keep a list of words that I commonly typo so I can learn how to spell them over time. It’s good to just have something like this echo at your in your .bashrc so every time you open a new terminal tab, you’ll see the right way to spell them and eventually you’ll read them enough to learn.

ambiguous
anonymity
authoritative
believe
character
convenience
corresponding
decommissioned
definitely
degradation
discipline
embarrassment
figuratively
frustrated
guarantee
interpretive
license
maintenance
maneuver
miniature
possession
privilege
receipt
receive
residual
ridiculous
weird

Shortest bit of JS to hide text after [time]

sean — Sat, 07 May 2011 21:33:05 +0000

I was trying to figure out the least amount of code that would render in a browser for 15ms, which is supposedly about the shortest time that subliminal advertising works. Here is what I came up with:



Test

If you can get it even shorter, leave a comment!

Python retreive SQLite results as dictionary of lists

sean — Tue, 19 Apr 2011 08:46:51 +0000

This is an interesting block of code that I just wrote while working on Beaker, the statistics package that goes along with MadScience

# numbers that are floating-point and must be handled as such
floats = ['up', 'time', 'data', 'resptime', 'trans', 'bw', 'concur', 'long', 'short']
# ditto for integers
ints = ['hits', 'ok', 'fail']

# init a new dictionary
mydict = {}

# for every item in the combination of the integers and the floats, create a key for it and assign the value to a blank list
for i in floats + ints:
    mydict[i] = []

# for every row returned by the SQLite query, iterate through all the integers, then all the floats
# for each different named value, go to the dict key that matches and add something to the value of that key, which is a list
# the value should be converted to the respective type and the key coming from the SQLite results (the column name in the DB) matches the names of our keys and thus can be iterated 1:1
for row in cursor.execute(myquery):
    for key in floats:
        mydict[key].append(float(row[key]))
    for key in ints:
       mydict[key].append(int(row[key]))

R1Wrangler

sean — Fri, 08 Apr 2011 22:09:18 +0000

I’m working on a full-blown webapp to manage our R1Soft CDP backup server cluster. We have around 1,000 servers and needed a good way to keep track of what backup server(s) they’re on, when they’re getting backed up, if they’re failing, disk space used, if they failed backups previously, etc. I also wanted to have a way to easily add backups to any existing backup server, so I created R1Wrangler: https://github.com/ip2k/R1-Wrangler . It’s still a work in progress and the DB schema isn’t even on the final revision yet, but it’s getting there and should be useful if you want to dive in to the R1Soft CDP Server 2.x XMLRPC API, OO PHP, normalised database schema, etc.

Clicky kitty to check it out!

My .vimrc

sean — Tue, 05 Apr 2011 22:00:32 +0000

Still a work in progress. I don’t use vim all the time, but more and more I see it as a huge time saver.

" General config
set nocompatible
set nowrap
set listchars=tab:>-,trail:-

set nu
set list
set showmatch
set autowrite
filetype plugin indent on
syntax on
set ruler

"make it so that jk, instead of navigating across actual lines, allows you
"to scroll up/down visual lines... so if you have a really long wrapped line,
"you can actually scroll down through it
nnoremap  gj
nnoremap  gk

" Customizing indentation so it just does what I expect it to
set tabstop=8
set softtabstop=4
set shiftwidth=4
set expandtab
set shiftround
set smarttab
set autoindent
set smartindent
set cindent
filetype indent on

" set shift-tab to unindent
imap  <<

" C-specific configuration
set cino=+0.5s
autocmd FileType c,cpp   set cindent

" Syntax highlighting for non-standard files
autocmd BufNewFile,BufRead *.thrift set filetype=c
" viki config
" au BufNewFile,BufRead *.viki :VikiMinorMode
" let g:vikiUseParentSuffix = 1

Scripting Siege for semi-automated testing

sean — Sat, 12 Mar 2011 20:28:41 +0000

More can be done with this, but at work, we’re benchmarking Magento with various changes to our hosting platform and I’m using the following to standardized tests:

[[ $1 ]] || echo 'Please specify a number of runs like this: ' $0 '[number of runs]'
for i in $(seq 1 $1); do
  echo ${i}'.)'
  siege --concurrent=100 --reps=100 -i -b -f urls-bench1.txt 2>&1 \
  |grep -v HTTP/1.1 |grep -v error |grep -vi siege |grep -v battle |grep -vi done \
  |grep -v FILE |grep -v annoying|grep -v chunk |grep -v show-logfile
  sleep 120
done

Put that in a script and save it. To run it, do:

bash benchmark.sh [number of runs]

WANdisco SVN installer without registering

sean — Fri, 01 Oct 2010 18:41:36 +0000

I really really really really hate stuff that requires you to register or enter an E-Mail address to get a download link, so I make an effort to post the actual link to that type of stuff all over the internet so people don’t have to register if they poke around a bit. http://www.bugmenot.com/ is a great site for finding logins to annoying sites, but some just require an e-mail address so they can spam you.

Screw that, and screw you WANdisco: If you need the SVN installer from them for CentOS 5, just hit the link below instead of filling out the form at http://www.wandisco.com/products/download_reg.php?download=centos : svninstall_centos5_wandisco.sh Download and rename to svninstall_centos5_wandisco.sh .

Bash script to pop a Gnome notification for IRC activity

sean — Thu, 30 Sep 2010 02:08:05 +0000

Tweak the vars as needed. This requires ‘ii’ , download from here: http://tools.suckless.org/ii/ or install with ‘apt-get install ii’ if using Ubuntu/Debian

Set debug to ‘true’ if you want live debug output. Filtering options coming soon.

#!/bin/bash

# trap ^C so we can clean up
trap sorry INT

# the hostname or IP of the IRC server
ircserver='10.0.120.98'

# the IRC channel
channel='#techs'

# the bot's IRC nick
nickname="$(uname -n)"

# the path to ii's irc directory (default is $HOME/irc)...NO TRAILING SLASH!
pathtoircdir="$HOME/irc"

# set to 'true' to enable debugging output
debug='false'

outfile="$pathtoircdir/$ircserver/$channel/out"
infile="$pathtoircdir/$ircserver/in"
joindelay='5'

sorry () {
	echo 'Caught ^C, killing ii now...'
	kill $iipid
	sleep 3
	while [ -d /proc/$iipid ]; do
		kill -9 $iipid
	done
exit 0
}

if [ "$(pidof ii)" ]; then
	echo 'ii is already running!  Exiting...'
	exit 1
fi

ii -s "$ircserver" -n "$nickname" &
iipid="$!"
echo "ii launched! PID: $iipid"
sleep "$joindelay"
# uncomment / edit the next line to identify to nickserv or send some other command after connecting
# echo '/msg nickserv identify SOMEPASS' > "$infile"

echo "/j $channel" > "$infile"
echo "channel joined!"

if [ "$debug" = 'true' ]; then
	echo "$(date) ircserver $ircserver , channel $channel , nickname $nickname , pathtoircdir $pathtoircdir "
fi

while true; do
	oldcount="$(cat $outfile | wc -l)"
	sleep 1
	newcount="$(cat $outfile | wc -l)"
	thediff="$(echo $newcount - $oldcount | bc)"

	if [ "$debug" = 'true' ]; then
		echo "$(date) oldcount $oldcount , new	count $newcount , thediff $thediff"
	fi

	if [ "$thediff" -gt '0' ]; then
		notify-send "$(tail -$thediff $outfile)"
	fi
done

Default BIOS passwords

sean — Tue, 09 Feb 2010 15:10:38 +0000

Here are some to try if you can’t open the case to short the password reset jumper:
AWARD_SW, j262 , HLT, SER, SKY_FOX, BIOSTAR, ALFAROME,
lkwpeter, j256, AWARD?SW, LKWPETER, Syxz, aLLy, 589589,
589721, awkward
AMI BIOS:
AMI, BIOS, PASSWORD, HEWITT RAND, AMI?SW, AMI_SW, LKWPETER,
A.M.I.

Credit goes to here