Vidul Nikolaev Petrov: Category programming

Getting Negative Number

root — Tue, 28 Oct 2008 08:34:00 -0600

positive = 10.01

# the negative equivalent: -10.01

negative = positive - (positive * 2)
negative = positive * -1 # or
negative = positive / -1 
negative = -positive # or 
negative = ---positive

Enigma

root — Wed, 09 Jul 2008 16:40:00 -0600

Here’s the mirror
Behind there is a screen
Turn around
On both ways you can get in
The experience of survival
Look around just people, can you hear their voice
Find the one who’ll guide you to the limits of your choice
The experience / of survival
Try to think about it …
That’s the chance to live your life and discover
Try to think about it
The experience of survival
The experience …
The experience of survival
The experience …

WEB 2.0 In NY

root — Wed, 09 Jul 2008 14:08:00 -0600

Google Chart API

root — Mon, 30 Jun 2008 01:33:00 -0600

Charts for a map (in this example I’ve included Spain, France, Italy and Norway):

more about this API

cheat sheets

root — Thu, 29 May 2008 18:06:00 -0600

command-line cheat sheets

279 cheat sheets:
$cheat sheets
$cheat unix_text

One of Unix’s most useful features is its large number of text/data manipulations programs. Some of the more propular include:

cat - concatenate and display files
cut - remove selected fields from each line of a file
sort - sort and collate lines
uniq - remove or report adjacent duplicate lines
awk - pattern scanning and processing language
sed - stream editor
tr - translate characters
diff - display line-by-line differences between pairs of text files
grep, egrep, fgrep - search a file for a string or regular expression
paste - join corresponding lines of several files, or subsequent lines of one
file
colrm - remove characters from specified columns within each line
expand, unexpand - expand TAB characters to SPACE characters, and vice versa

Geerd Wilders: Enough is enough

root — Fri, 28 Mar 2008 14:06:00 -0600

Scalar || List context

root — Tue, 12 Feb 2008 13:12:00 -0700

Perl

 $a  = ("a", "b", "c"); # $a is "c" - the last element
($a) = ("a", "b", "c"); # $a is "a" - the first element

Ruby

 obj        = ["a", "b", "c"] # obj is Array - ["a", "b", "c"]
 obj, b, c = ["a", "b", "c"] # obj is String - "a"

Lotto checking script

root — Tue, 12 Feb 2008 12:16:00 -0700

The idea comes from http://www.waider.ie/hacks/workshop/perl/lotto.pl script.

Should I be so wasteful? No:

irb

my_numbers       = [1,2,3,4,5,6]
winning_numbers = [1,2,3,41,42,43]

result = 6 - (winning_numbers - my_numbers).size

puts "#{result} " + 
  if not result.eql? 0
    "hits"
  else
    "hit"
  end

getting root acccess without sudo

root — Sat, 29 Dec 2007 08:31:00 -0700

#include <sys/types.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int main(int argc, char** argv)
{
    int root_id = 0;
    char *command = argv[1];

    if(!command)
        command = "/bin/bash";

    setuid(root_id);
    system(command);
    exit(0);
}

root# gcc -o temproot temproot.c
root# chmod +s temproot
nobody$ alias root=’temproot “su – root”’
nobody$ root

List Values and Arrays

root — Fri, 30 Nov 2007 07:28:00 -0700

Perl

($a, $b) = (1, 2);
 @arr    = (1, 2);

Python

 a, b = 1, 2
 arr  = 1, 2;

Ruby

 a, b = 1, 2
 arr  = 1, 2
 arr  = 1,2, *[11,22] # the same as 
 arr  = [1,2, [11,22]].flatten

the ’*’ example was stolen from Ola Bini’s blog

Opera password recovery

root — Mon, 29 Oct 2007 18:44:00 -0600

Unwand – fast and free program for wand password recovery.

Ruby one-liners (file manipulation)

root — Fri, 20 Jul 2007 11:11:00 -0600


# number each line of a file
ruby -ne 'puts "#{$.}\t#{$_}"' file.txt

# print all non-blank lines
ruby -pe '$_.chomp.empty? and next' file.txt

# number and print all non-blank lines
ruby -ne '$_.chomp.empty? or print $.,"\t", $_' file.txt

# number and print each blank line
ruby -ne 'puts $. if $_.chomp.empty?' file.txt

# reverse order of lines (`tac` style)
ruby -e 'puts File.open($<.filename).readlines.reverse' file.txt

# print matched string from lines, matching the pattern
ruby -ne 'puts $_.scan(/^\w+/)' /etc/passwd

# triple space a file and reverse order of lines
ruby -e '$,="\n\n\n"; puts File.readlines($<.filename).reverse.join' file.txt

# print first line of a file (emulate 'head -1')
ruby -ne 'puts $_; break' file.txt
ruby -pe '$. == 1 or break' file.txt

# print last line of a file (emulates 'tail -1')
ruby -ne 'END{puts $_}' file.txt

# print last line number (emulates 'wc -l')
ruby -e 'loop{gets or break}; puts $.' file.txt

# print only lines that match a regular expression (emulates 'grep')
ruby -pe 'next if not /regex/' file.txt

# print only lines that do not match a regular expression (emulates 'grep -v')
ruby -pe 'next if /regex/' file.txt

# print section of file between two regular expressions, /^root/ and /^nobody/
ruby -ne 'puts $_ if /^root/../^nobody/' file.txt

# print file and remove duplicate, consecutive lines from a file (emulates 'uniq')
ruby -ne '$_.eql? $; or puts $_;$; = $_;' file.txt

# print file except for blank lines
ruby -pe 'next if $_.chomp.empty?' file.txt
ruby -pe 'next if /^\s*$/' file.txt
ruby -pe 'next if $_.split(/\S+/).size < 2' file.txt

# print file except for lines, starting with digit (unclear and inefficient)
ruby -pe 'next if (48..57).to_a.include?($_.split(//)[0][0])' file.txt

# delete all leading blank lines at top of file
ruby -pe '$,="$." if not $_.chomp.empty?; $, or next' file.txt

# print section of file from regex to end of file
ruby -pe '$,="$." if /regex/; $, or next' file.txt

# delete leading and trailing whitespace from each line
ruby -pe '$_.strip!.sub!(/$/, "\n")' file.txt
ruby -ne 'puts $_.strip! + $/' file.txt

# delete leading whitespace from the beginning of each line
ruby -ne 'puts $_.lstrip! || $_' file.txt

# convert DOS newlines (CR/LF) to Unix format (LF)
ruby -i -pe 'sub(/\r\n/, "\n")' file.txt