Restore the packages list in your Debian Linux box

Backup

dpkg --get-selections > packageList.txt

Restore

sudo apt-get update
sudo dpkg --set-selections < packageList.txt
sudo apt-get dselect-upgrade

Want to apply just a part of your patch(Only on few files or even a few lines)?

Starting tag = MY_PORTION_START
Ending tag = MY_PORTION_END

awk 'BEGIN {start=0} /MY_PORTION_END/ {start=0} {if (start == 1) print} /MY_PORTION_START/ {start=1}' patch.diff | patch -p 1

You have to insert these tags into your patch file depends on your need.

Python - Converting character string to HEXA string

ord(c): Given a string of length one, return an integer representing the Unicode code point of the character when the argument is a unicode object, or the value of the byte when the argument is an 8-bit string.

>>> ord("a")
97
>>> ord("\t")
9

hex(n): Convert an integer number to a hexadecimal string

>>> hex (97)
'0x61'
>>> hex (9)
'0x9'

We do not need first to characters in the hex output.

>>> hex (97)[2:]
'61'
>>> hex (9)[2:]
'9'

zfill(witdh): Return the numeric string left filled with zeros in a string of length width.

>>> hex (97)[2:].zfill (3)
'061'
>>> hex (9)[2:].zfill (2)
'09'

Put of together,

>>> s="\x08\t\x07khr\x00"
>>> "".join ([hex (ord(c))[2:].zfill(2) for c in s])
'0809076b687200'

Reference:
href=http://docs.python.org/library/functions.html

Perl - Converting character string to HEXA string

   $buf =~ s/(.)/sprintf("%0X",ord($1))/eg;

Substitution Operator Modifiers
Here is the list of all modifiers used with substitution operator

Modifier Description
     i   Makes the match case insensitive
     m   Specifies that if the string has newline or carriage
         return characters, the ^ and $ operators will now
         match against a newline boundary, instead of a
         string boundary
     o   Evaluates the expression only once
     s   Allows use of . to match a newline character
     x   Allows you to use white space in the expression
         for clarity
     g   Replaces all occurrences of the found expression
         with the replacement text
     e   Evaluates the replacement as if it were a Perl statement,
         and uses its return value as the replacement text

References:
http://icfun.blogspot.com/2009/05/perl-convert-character-string-into-hex.html
http://www.tutorialspoint.com/perl/perl_regular_expression.htm

Command-line dictionary

It just parse the website wordnetweb and extract the meaning of the word/phrase given. You need lynx to run this script successfully.

#!/bin/bash

lynx -dump "http://wordnetweb.princeton.edu/perl/webwn?s=$1" | awk '/\(lexical\) relations/ {flag=1; next;} /WordNet home page/ {flag=0;}{if (flag == 1) print;}' | grep --color -100 -E "(Verb|Adjective|Noun|Adverb|\(|\)|\[|\])"

exit 0

References:
http://ubuntuforums.org/showthread.php?t=371482
http://wordnetweb.princeton.edu/perl/webwn

Heapsort

Heap
 Sort in place
 Binary tree
 Worst case runtime (n lg n)

PARENT(i) -> i/2
Left (i)  -> 2i
Right (i) -> 2i + 1

MAX_HEAP

A[PARENT(i)] >= A[i]

MIN_HEAP

A[PARENT(i)] <= A[i]

MAX-HEAPIFY
 Maintain the max-heap propert

 MAX-HEAPIFY (A, i)
   l = LEFT (i)
   r = RIGHT (i)
   if l <= A:heap-size and A[l] > A[i]
        largest = l
   else largest = i
   if r <= A.heap-size and A[r] > A[largest]
        largest = r
   if largest != i
        exchange A[i] with A[largest]
        MAX-HEAPIFY (A, largest)

Heap Sorting

 HEAPSORT (A)
  BUILD-MAX-HEAP (A)
  for i = A.length downto 2
    exchange A[1] with A[i]
    A.heap-size = A.heap-size - 1
    MAX-HEAPIFY (A, 1)

Priority queues
 One of the main usage is that we can use max-priority queues to schedule jobs on a shared computer.The max-priority queue keeps track of the jobs to
be performed and their relative priorities. When a job is finished or interrupted,the scheduler selects the highest-priority job from among those pending by calling EXTRACT-MAX. The scheduler can add a new job to the queue at any time by calling INSERT.

Reference: Introduction to Algorithms By Thomas H. Cormen, Charles E. Leiserson, Ronald L. Rivest, Clifford Stein

Good starting point for Android developers

Here you go...http://www.linuxconfig.org/get-started-with-android-application-development-using-linux-and-android-sdk