Sunday, 28 October 2007

Various Modulation Scheme







Debugging with Python (PDB) - Quick and Easy Tutorial

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Debugging in Python

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Updated: 2007-03-21
Contact Stephen Ferg


Creative Commons Licence This work is licensed under the Creative Commons Attribution 2.0 License You are free to copy, distribute, and display the work, and to make derivative works (including translations). If you do, you must give the original author credit. The author specifically permits (and encourages) teachers to post, reproduce, and distribute some or all of this material for use in their classes or by their students.


As a programmer, one of the first things that you need for serious program development is a debugger.

Python has a debugger, which is available as a module called pdb (for "Python DeBugger", naturally!). Unfortunately, most discussions of pdb are not very useful to a Python newbie -- most are very terse and simply rehash the description of pdb in the Python library reference manual. The discussion that I have found most accessible is in the first four pages of Chapter 27 of the Python 2.1 Bible.

So here is my own personal gentle introduction to using pdb. It assumes that you are not using any IDE -- that you're coding Python with a text editor and running your Python programs from the command line.

Some Other Debugger Resources


Getting started -- pdb.set_trace()

To start, I'll show you the very simplest way to use the Python debugger.

  1. Let's start with a simple program, epdb1.py.
        # epdb1.py -- experiment with the Python debugger, pdb
    a = "aaa"
    b = "bbb"
    c = "ccc"
    final = a + b + c
    print final
  2. Insert the following statement at the beginning of your Python program. This statement imports the Python debugger module, pdb.
    import pdb
  3. Now find a spot where you would like tracing to begin, and insert the following code:
    pdb.set_trace()
    So now your program looks like this. (Click HERE for the source code.)
            # epdb1.py -- experiment with the Python debugger, pdb
    import pdb
    a = "aaa"
    pdb.set_trace()
    b = "bbb"
    c = "ccc"
    final = a + b + c
    print final
  4. Now run your program from the command line as you usually do, which will probably look something like this:
            PROMPT> python epdb1.py

When your program encounters the line with pdb.set_trace() it will start tracing. That is, it will (1) stop, (2) display the "current statement" (that is, the line that will execute next) and (3) wait for your input. You will see the pdb prompt, which looks like this:

           (Pdb)

Execute the next statement... with "n" (next)

At the (Pdb) prompt, press the lower-case letter "n" (for "next") on your keyboard, and then press the ENTER key. This will tell pdb to execute the current statement. Keep doing this -- pressing "n", then ENTER.

Eventually you will cometo the end of your program, and it will terminate and return you to the normal command prompt.

Congratulations! You've just done your first debugging run!

Repeating the last debugging command... with ENTER

This time, do the same thing as you did before. Start your program running. At the (Pdb) prompt, press the lower-case letter "n" (for "next") on your keyboard, and then press the ENTER key.

But this time, after the first time that you press "n" and then ENTER, don't do it any more. Instead, when you see the (Pdb) prompt, just press ENTER. You will notice that pdb continues, just as if you had pressed "n". So this is Handy Tip #1:

If you press ENTER without entering anything, pdb will re-execute the last command that you gave it.

In this case, the command was "n", so you could just keep stepping through the program by pressing ENTER.

Notice that as you passed the last line (the line with the "print" statement), it was executed and you saw the output of the print statement ("aaabbbccc") displayed on your screen.

Quitting it all... with "q" (quit)

The debugger can do all sorts of things, some of which you may find totally mystifying. So the most important thing to learn now -- before you learn anything else -- is how to quit debugging!

It is easy. When you see the (Pdb) prompt, just press "q" (for "quit") and the ENTER key. Pdb will quit and you will be back at your command prompt. Try it, and see how it works.

Printing the value of variables... with "p" (print)

The most useful thing you can do at the (Pdb) prompt is to print the value of a variable. Here's how to do it.

When you see the (Pdb) prompt, enter "p" (for "print") followed by the name of the variable you want to print. And of course, you end by pressing the ENTER key.

Note that you can print multiple variables, by separating their names with commas (just as in a regular Python "print" statement). For example, you can print the value of the variables a, b, and c this way:

          p a, b, c

When does pdb display a line?

Suppose you have progressed through the program until you see the line

          final = a + b + c

and you give pdb the command

          p final

You will get a NameError exception. This is because, although you are seeing the line, it has not yet executed. So the final variable has not yet been created.

Now press "n" and ENTER to continue and execute the line. Then try the "p final" command again. This time, when you give the command "p final", pdb will print the value of final, which is "aaabbbccc".

Turning off the (Pdb) prompt... with "c" (continue)

You probably noticed that the "q" command got you out of pdb in a very crude way -- basically, by crashing the program.

If you wish simply to stop debugging, but to let the program continue running, then you want to use the "c" (for "continue") command at the (Pdb) prompt. This will cause your program to continue running normally, without pausing for debugging. It may run to completion. Or, if the pdb.set_trace() statement was inside a loop, you may encounter it again, and the (Pdb) debugging prompt will appear once more.

Seeing where you are... with "l" (list)

As you are debugging, there is a lot of stuff being written to the screen, and it gets really hard to get a feeling for where you are in your program. That's where the "l" (for "list") command comes in. (Note that it is a lower-case "L", not the numeral "one" or the capital letter "I".)

"l" shows you, on the screen, the general area of your program's souce code that you are executing. By default, it lists 11 (eleven) lines of code. The line of code that you are about to execute (the "current line") is right in the middle, and there is a little arrow "-->" that points to it.

So a typical interaction with pdb might go like this

  • The pdb.set_trace() statement is encountered, and you start tracing with the (Pdb) prompt
  • You press "n" and then ENTER, to start stepping through your code.
  • You just press ENTER to step again.
  • You just press ENTER to step again.
  • You just press ENTER to step again. etc. etc. etc.
  • Eventually, you realize that you are a bit lost. You're not exactly sure where you are in your program any more. So...
  • You press "l" and then ENTER. This lists the area of your program that is currently being executed.
  • You inspect the display, get your bearings, and are ready to start again. So....
  • You press "n" and then ENTER, to start stepping through your code.
  • You just press ENTER to step again.
  • You just press ENTER to step again. etc. etc. ec.

Stepping into subroutines... with "s" (step into)

Eventually, you will need to debug larger programs -- programs that use subroutines. And sometimes, the problem that you're trying to find will lie buried in a subroutine. Consider the following program. (Click HERE for the source code.)

        # epdb2.py -- experiment with the Python debugger, pdb
import pdb

def combine(s1,s2): # define subroutine combine, which...
s3 = s1 + s2 + s1 # sandwiches s2 between copies of s1, ...
s3 = '"' + s3 +'"' # encloses it in double quotes,...
return s3 # and returns it.

a = "aaa"
pdb.set_trace()
b = "bbb"
c = "ccc"
final = combine(a,b)
print final

As you move through your programs by using the "n" command at the (Pdb) prompt, you will find that when you encounter a statement that invokes a subroutine -- the final = combine(a,b) statement, for example -- pdb treats it no differently than any other statement. That is, the statement is executed and you move on to the next statement -- in this case, to print final.

But suppose you suspect that there is a problem in a subroutine. In our case, suppose you suspect that there is a problem in the combine subroutine. What you want -- when you encounter the final = combine(a,b) statement -- is some way to step into the combine subroutine, and to continue your debugging inside it.

Well, you can do that too. Do it with the "s" (for "step into") command.

When you execute statements that do not involve function calls, "n" and "s" do the same thing -- move on to the next statement. But when you execute statements that invoke functions, "s", unlike "n", will step into the subroutine. In our case, if you executed the final = combine(a,b) statement using "s", then next statement that pdb would show you would be the first statement in the combine subroutine:

               def combine(s1,s2): 

and you will continue debugging from there.

Continuing... but just to the end of the current subroutine... with "r" (return)

When you use "s" to step into subroutines, you will often find yourself trapped in a subroutine. You have examined the code that you're interested in, but now you have to step through a lot of uninteresting code in the subroutine.

In this situation, what you'd like to be able to do is just to skip ahead to the end of the subroutine. That is, you want to do something like the "c" ("continue") command does, but you want just to continue to the end of the subroutine, and then resume your stepping through the code.

You can do it. The command to do it is "r" (for "return" or, better, "continue until return"). If you are in a subroutine and you enter the "r" command at the (Pdb) prompt, pdb will continue executing until the end of the subroutine. At that point -- the point when it is ready to return to the calling routine -- it will stop and show the (Pdb) prompt again, and you can resume stepping through your code.

You can do anything at all at the (Pdb) prompt ...

Sometimes you will be in the following situation -- You think you've discovered the problem. The statement that was assigning a value of, say, "aaa" to variable var1 was wrong, and was causing your program to blow up. It should have been assigning the value "bbb" to var1.

... at least, you're pretty sure that was the problem...

What you'd really like to be able to do, now that you've located the problem, is to assign "bbb" to var1, and see if your program now runs to completion without bombing.

It can be done!

One of the nice things about the (Pdb) prompt is that you can do anything at it -- you can enter any command that you like at the (Pdb) prompt. So you can, for instance, enter this command at the (Pdb) prompt.

               (Pdb) var1 = "bbb"

You can then continue to step through the program. Or you could be adventurous -- use "c" to turn off debugging, and see if your program will end without bombing!

... but be a little careful! 1

Since you can do anything at all at the (Pdb) prompt, you might decide to try setting the variable b to a new value, say "BBB", this way:

               (Pdb) b = "BBB"

If you do, pdb produces a strange error message about being unable to find an object named '= "BBB" '. Why???

What happens is that pdb attempts to execute the pdb b command for setting and listing breakpoints (a command that we haven't discussed). It interprets the rest of the line as an argument to the b command, and can't find the object that (it thinks) is being referred to. So it produces an error message.

So how can we assign a new value to b? The trick is to start the command with an exclamation point (!).

               (Pdb)!b = "BBB"

An exclamation point tells pdb that what follows is a Python statement, not a pdb command.

The End

Well, that's all for now. There are a number of topics that I haven't mentioned, such as help, aliases, and breakpoints. For information about them, try the online reference for pdb commands on the Python documentation web site at www.python.org/doc/current/lib/debugger-commands.html. In addition, I recommend Jeremy Jones' article Interactive Debugging in Python in O'Reilly's Python DevCenter.

I hope that this introduction to pdb has been enough to get you up and running fairly quickly and painlessly. Good luck!

—Steve Ferg


1 Thanks to Dick Morris for the information in this section.

Applications of Pascal's Triangle

application of pascal triangle

====================
(x-1)^2 = x^2 +2*x+1 (1 2 1)
(x-1)^4 = x^4 +4*x^3+6*x^2+4*x + 1 (1 4 6 4 1)

Pascal's Triangle

One of the most interesting Number Patterns is Pascal's Triangle (named after Blaise Pascal, a famous French Mathematician and Philosopher).

To build the triangle, start with "1" at the top, then continue placing numbers below it in a triangular pattern.

Each number is just the two numbers above it added together.

(Here I have highlighted that 1+3 = 4)

Patterns Within the Triangle

Diagonals

The first diagonal is, of course, just "1"s, and the next diagonal has the Counting Numbers (1,2,3, etc).

The third diagonal has the triangular numbers

(The fourth diagonal, not highlighted, has the tetrahedral numbers.)

Odds and Evens

If you color the Odd and Even numbers, you end up with a pattern the same as the Sierpinski Triangle

Horizontal Sums

What do you notice about the horizontal sums? Is there a pattern? Isn't it amazing!

It doubles each time (powers of 2).

Fibonacci Sequence

Try this: make a pattern by going up and then along, then add up the squares (as illustrated) ... you will get the Fibonacci Sequence.

(The Fibonacci Sequence is made by adding the two previous numbers, for example 3+5=8, then 5+8=13, etc)

Using Pascal's Triangle

Heads and Tails

Pascal's Triangle can show you how many ways heads and tails can combine. This can then show you "the odds" (or probability) of any combination.

For example, if you toss a coin three times, there is only one combination that will give you three heads (HHH), but there are three that will give two heads and one tail (HHT, HTH, THH), also three that give one head and two tails (HTT, THT, TTH) and one for all Tails (TTT). This is the pattern "1,3,3,1" in Pascal's Triangle.

Tosses Possible Results (Grouped) Pascal's Triangle
1 H
T
1, 1
2 HH
HT TH
TT
1, 2, 1
3 HHH
HHT, HTH, THH
HTT, THT, TTH
TTT
1, 3, 3, 1
4 HHHH
HHHT, HHTH, HTHH, THHH
HHTT, HTHT, HTTH, THHT, THTH, TTHH
HTTT, THTT, TTHT, TTTH
TTTT
1, 4, 6, 4, 1
... etc ...

What is the probability of getting exactly two heads with 4 coin tosses?

There are 1+4+6+4+1 = 16 (or 4×4=16) possible results, and 6 of them give exactly two heads. So the probability is 6/16, or 37.5%

Ref :www.mathsisfun.com/pascals-triangle.html

Friday, 26 October 2007

Chinese version Of matrix ( 3D )

Send a Common Scrap to All Your Friends With a Single Click!

Ever wondered how much time it took you to wish your friends on orkut - 'A Happy New Year' ?
Are you fed up of the individual scrapping which not only is boring but also time consuming. If yes! Then this one's for you!


Works With:





Procedure :

Ref: http://orkutplus.blogspot.com/2007/01/send-common-scrap-to-all-your-friends.html

Microsoft Surface - Exclusive Review

Cutting Edge Technology at Microsoft !!




Ref : utube

Thursday, 25 October 2007

Mozilla FireFox Recommended Add-on


Everyday use :


AdBlock Plus

a filter subscription when Adblock Plus starts up the first time, then even this simple task will usually be unnecessary: the filter subscription will block most advertisements fully automatically

Colourful Tabs

Colors every tab in a different color and makes them easy to distinguish while beautifying the overall appearance of the interface. An essential...


Flash Block

This plunging blocks any flash contains on web page. which is quite useful if you want to save bandwidth.


Tab mix plus

you can have as many tabs as you like. It includes such features as duplicating tabs, controlling tab focus, tab clicking options, undo closed tabs and windows, plus much more. It also includes a full-featured session manager with crash recovery that can save and restore combinations of opened tabs and windows.

McAfee SiteAdvisor for Firefox 26.5

SiteAdvisor helps protect you from all kinds of Web-based security threats including spyware, adware, spam, viruses, browser-based attacks, phishing, online fraud and identity theft.

Download Statusbar
View and manage downloads from a tidy status bar - without the download window getting in the way of your web browsing.


Web developments :

FireBug
======

allows you to debug the scripts. useful if you are doing web development. ( where you don't want to invest in heavy duty, high cost tools)

View source
========

better then conventional source code viewer. this shows coloured

Internet Security :

Local Link
=======

this blocks any script execution from webpage. like scripts which can execute lunches something. you can block/give permission by using local link ( which is a strong consequence of Internet explorer )

Wednesday, 24 October 2007

ARM TDMI ??

T (Thumb)
The T stands for Thumb instruction set which addresses the issue of code density. Specifically, Thumb mode allows instructions to be 16-bits instead of 32-bits thus reducing code density. A processor having the T suffix can thus run Thumb code.

D (Debug)

The D stand for debug support. This means that the specific ARM7 you are using offers on-chip debug support, generally through a J-Tag interface.

M (Multiply)

The M means that the CPU contains a hardware multiply instruction.

I (EmbeddedICE macrocell)

Is the debug hardware built into the processor that allows breakpoints and watchpoints to be set.

8051 Core + Full JTAG support,100 MIPS

Silicon Laboratories (Full JTAG + 8051 Core)


provides CPUs of 8051 core with Full JTAG support which can really boost up your development time with features like up to 100 MIPS Mixed-Signal 8051 with 32 - 128 I/O Lines, 5-7 Timers, PCA, Capture/Compare, SPI, SMBus, I2C, multi pal UARTS, Watchdog Timer, Real-Time Clock, 8 Channel (10/12-bit) A/D, Internal Voltage Reference, 2 Channel (12-bit) D/A, On-Chip Temp Sensor, 8/16K Bytes XRAM, 64K Byte In-System Programmable FLASH, 256 Bytes RAM.

you really have a chip which is a real SOC (system on chip).. might reduce your total cost of board by reducing the size and components needed.

The JTAG debug adapter can be bought from the site at cost of USD$ 20. (bits its competitors by 3+ times margin)

Example :C8051F131/132/133

Tuesday, 23 October 2007

Run your car on Water

Prototype car runs 100 miles on four ounces of water as fuel


Click to ZoomWhile his unique electrolysis process – working simply with water and electricity – was originally designed to work in welding factories as a replacement for acetylene torches, a whole new application has come to light from Denny Klein, who recently filed a patent on his solution. He has converted his 1994 Ford Escort to run either as a water-gas hybrid, or on water alone.

While the tip of the welder is cool to the touch, the water-powered torch can burn through charcoal and get tungsten to "light up like a sparkler." But when it comes to powering a vehicle, this prototype could drive for 100 miles on only four ounces of water. Technically, the car isn't running on water, because the H20 is converted to HHO gas. This is said to provide the "atomic power of hydrogen", while maintaining the "chemical stability of water."

He has already attracted the attention of an unnamed American automaker, and Klein has been invited to the Washington to demonstrate his technology, with word that he is now working on a water-gasoline hybrid Hummer for US military.

Of course, none of this has been confirmed, so it's hard to say whether Mr. Klein's invention is a) for real, b) actually usable or c) a complete hoax. For example, many have said that the energy required to convert H2O to HHO is greater than that produced when the HHO is burned.


you can see the experiments and working model of this technology on UTUBE.


Ref: http://www.mobilemag.com/content/100/354/C8115/

Run your car on Water

Prototype car runs 100 miles on four ounces of water as fuel


Click to ZoomWhile his unique electrolysis process – working simply with water and electricity – was originally designed to work in welding factories as a replacement for acetylene torches, a whole new application has come to light from Denny Klein, who recently filed a patent on his solution. He has converted his 1994 Ford Escort to run either as a water-gas hybrid, or on water alone.

While the tip of the welder is cool to the touch, the water-powered torch can burn through charcoal and get tungsten to "light up like a sparkler." But when it comes to powering a vehicle, this prototype could drive for 100 miles on only four ounces of water. Technically, the car isn't running on water, because the H20 is converted to HHO gas. This is said to provide the "atomic power of hydrogen", while maintaining the "chemical stability of water."

He has already attracted the attention of an unnamed American automaker, and Klein has been invited to the Washington to demonstrate his technology, with word that he is now working on a water-gasoline hybrid Hummer for US military.

Of course, none of this has been confirmed, so it's hard to say whether Mr. Klein's invention is a) for real, b) actually usable or c) a complete hoax. For example, many have said that the energy required to convert H2O to HHO is greater than that produced when the HHO is burned.


you can see the experiments and working model of this technology on UTUBE.


Ref: http://www.mobilemag.com/content/100/354/C8115/

Search & replace multiple documents with smart queries , batch replace lines of text!

Advanced Find And Replace 3.0


Features:
Search files with smart queries as with AltaVista or Google.
Replace simple or multiline text in multiple files.
Complete search and replace in Microsoft Office Word, Excel and Power Point files.
With batch replace operation you can easily replace or update hundreds of different links in several files.
Preview found text as with Google.
Possibility to replace in file names: it can be used as full-featured file re-namer.
Use Perl-style regular expressions for replacements of any complexity.
Saves results in XML and other formats.
Works with command line params.
Extremely fast, easy to use and excellent documentation is included.
It is a great time-saver for programmers and Web masters

more info @http://www.abacre.com/afr/index.htm

Monday, 22 October 2007

multipal lable error with keil

if you have label inside macro. and you are calling that macro more then once then keil will raise multipal label problem.

you have to declare label inside the macro as a local.

Example :

TEST_SPIBUSY macro
local spi01
push acc
spi01:
mov a,SPI0CFG
anl a,#80
jb acc.7, spi01
clr SPIF
pop acc
endm

Saturday, 20 October 2007

UBUNTU -> linux for human beings

Operating system which is stable,Free of Charge, open source and known world wild.

Which comes with different variants ... with different initiatives as given bellow.

Kubuntu

Kubuntu is a user friendly operating system based on KDE, the K Desktop Environment

Edubuntu

Edubuntu is an operating system designed with education in mind.

  • An organisation or Education Ministry that is wanting to take full advantage of the benefits that open source software offers to the educational environment.

  • Educators and school personnel who would like to set up Edubuntu in a networked learning environment.

  • Home users who would like to have a standalone computer system that focuses on education for the younger members of the household.

Edubuntu gathers together the best available free software and digital materials for education.

"It can run on inexpensive, 10-year-old IBM-compatible computer as well as brand new I64-based systems"

Xubuntu

Xubuntu is a complete GNU/Linux. It is lighter on system requirements and tends to be more efficient than Ubuntu with GNOME or KDE, since it uses the Xfce Desktop environment, which makes it ideal for old or low-end machines.

Gobuntu

The fully open source operating system. This means there will be no firmware, drivers, applications, or content included in Gobuntu that does not include the full source or whose license does not provide the right to use, study, modify, and redistribute the body of work

How To Become A Hacker

Few years back i had attended Mr. Ankit Fadia's So called "Hacking Garu" at IIT powai. there ware plenty of people who attended the seminar but effectively there was nothing useful rather then simple tricks using ready made software. (total useless).. One of the best tutorial of becoming a hacker is written by Eric Steven the real guru..


Ref : http://www.catb.org/%7Eesr/faqs/hacker-howto.html

======================================

How To Become A Hacker


Revision History
Revision 1.3521 Mar 2007esr
Add note about live CDs, and ten years to mastery.
Revision 1.3503 Aug 2006esr
Minor fixes.
Revision 1.3407 Mar 2006esr
Remove C# from the list of languages to be avoided now that Mono is out of beta.
Revision 1.3329 Nov 2005esr
Add a pointer to Peter Norvig's excellent essay.
Revision 1.3229 Jun 2005esr
Substantial new material on not solving problems twice. Answer a FAQ on hacking and open-source programming. The three questions that reveal if you are already a hacker.
Revision 1.3122 Mar 2005esr
Added a link to another Paul Graham essay, and advice on how to pick a first project. More translation-link updates.
Revision 1.302 Mar 2005esr
Added and updated many translation links.

Why This Document?

As editor of the Jargon File and author of a few other well-known documents of similar nature, I often get email requests from enthusiastic network newbies asking (in effect) "how can I learn to be a wizardly hacker?". Back in 1996 I noticed that there didn't seem to be any other FAQs or web documents that addressed this vital question, so I started this one. A lot of hackers now consider it definitive, and I suppose that means it is. Still, I don't claim to be the exclusive authority on this topic; if you don't like what you read here, write your own.

If you are reading a snapshot of this document offline, the current version lives at http://catb.org/~esr/faqs/hacker-howto.html.

Note: there is a list of Frequently Asked Questions at the end of this document. Please read these—twice—before mailing me any questions about this document.

Numerous translations of this document are available: Arabic Bulgarian, Catalan, Chinese (Simplified), Danish, Dutch, Estonian, Farsi, Finnish, German, Greek Hebrew, Italian Japanese, Norwegian, Polish, Portuguese (Brazilian), Romanian Russian Spanish, Turkish, and Swedish. Note that since this document changes occasionally, they may be out of date to varying degrees.

The five-dots-in-nine-squares diagram that decorates this document is called a glider. It is a simple pattern with some surprising properties in a mathematical simulation called Life that has fascinated hackers for many years. I think it makes a good visual emblem for what hackers are like — abstract, at first a bit mysterious-seeming, but a gateway to a whole world with an intricate logic of its own. Read more about the glider emblem here.

What Is a Hacker?

The Jargon File contains a bunch of definitions of the term ‘hacker’, most having to do with technical adeptness and a delight in solving problems and overcoming limits. If you want to know how to become a hacker, though, only two are really relevant.

There is a community, a shared culture, of expert programmers and networking wizards that traces its history back through decades to the first time-sharing minicomputers and the earliest ARPAnet experiments. The members of this culture originated the term ‘hacker’. Hackers built the Internet. Hackers made the Unix operating system what it is today. Hackers run Usenet. Hackers make the World Wide Web work. If you are part of this culture, if you have contributed to it and other people in it know who you are and call you a hacker, you're a hacker.

The hacker mind-set is not confined to this software-hacker culture. There are people who apply the hacker attitude to other things, like electronics or music — actually, you can find it at the highest levels of any science or art. Software hackers recognize these kindred spirits elsewhere and may call them ‘hackers’ too — and some claim that the hacker nature is really independent of the particular medium the hacker works in. But in the rest of this document we will focus on the skills and attitudes of software hackers, and the traditions of the shared culture that originated the term ‘hacker’.

There is another group of people who loudly call themselves hackers, but aren't. These are people (mainly adolescent males) who get a kick out of breaking into computers and phreaking the phone system. Real hackers call these people ‘crackers’ and want nothing to do with them. Real hackers mostly think crackers are lazy, irresponsible, and not very bright, and object that being able to break security doesn't make you a hacker any more than being able to hotwire cars makes you an automotive engineer. Unfortunately, many journalists and writers have been fooled into using the word ‘hacker’ to describe crackers; this irritates real hackers no end.

The basic difference is this: hackers build things, crackers break them.

If you want to be a hacker, keep reading. If you want to be a cracker, go read the alt.2600 newsgroup and get ready to do five to ten in the slammer after finding out you aren't as smart as you think you are. And that's all I'm going to say about crackers.

The Hacker Attitude

Hackers solve problems and build things, and they believe in freedom and voluntary mutual help. To be accepted as a hacker, you have to behave as though you have this kind of attitude yourself. And to behave as though you have the attitude, you have to really believe the attitude.

But if you think of cultivating hacker attitudes as just a way to gain acceptance in the culture, you'll miss the point. Becoming the kind of person who believes these things is important for you — for helping you learn and keeping you motivated. As with all creative arts, the most effective way to become a master is to imitate the mind-set of masters — not just intellectually but emotionally as well.

Or, as the following modern Zen poem has it:


To follow the path:
look to the master,
follow the master,
walk with the master,
see through the master,
become the master.

So, if you want to be a hacker, repeat the following things until you believe them:

1. The world is full of fascinating problems waiting to be solved.

Being a hacker is lots of fun, but it's a kind of fun that takes lots of effort. The effort takes motivation. Successful athletes get their motivation from a kind of physical delight in making their bodies perform, in pushing themselves past their own physical limits. Similarly, to be a hacker you have to get a basic thrill from solving problems, sharpening your skills, and exercising your intelligence.

If you aren't the kind of person that feels this way naturally, you'll need to become one in order to make it as a hacker. Otherwise you'll find your hacking energy is sapped by distractions like sex, money, and social approval.

(You also have to develop a kind of faith in your own learning capacity — a belief that even though you may not know all of what you need to solve a problem, if you tackle just a piece of it and learn from that, you'll learn enough to solve the next piece — and so on, until you're done.)

2. No problem should ever have to be solved twice.

Creative brains are a valuable, limited resource. They shouldn't be wasted on re-inventing the wheel when there are so many fascinating new problems waiting out there.

To behave like a hacker, you have to believe that the thinking time of other hackers is precious — so much so that it's almost a moral duty for you to share information, solve problems and then give the solutions away just so other hackers can solve new problems instead of having to perpetually re-address old ones.

Note, however, that "No problem should ever have to be solved twice." does not imply that you have to consider all existing solutions sacred, or that there is only one right solution to any given problem. Often, we learn a lot about the problem that we didn't know before by studying the first cut at a solution. It's OK, and often necessary, to decide that we can do better. What's not OK is artificial technical, legal, or institutional barriers (like closed-source code) that prevent a good solution from being re-used and force people to re-invent wheels.

(You don't have to believe that you're obligated to give all your creative product away, though the hackers that do are the ones that get most respect from other hackers. It's consistent with hacker values to sell enough of it to keep you in food and rent and computers. It's fine to use your hacking skills to support a family or even get rich, as long as you don't forget your loyalty to your art and your fellow hackers while doing it.)

3. Boredom and drudgery are evil.

Hackers (and creative people in general) should never be bored or have to drudge at stupid repetitive work, because when this happens it means they aren't doing what only they can do — solve new problems. This wastefulness hurts everybody. Therefore boredom and drudgery are not just unpleasant but actually evil.

To behave like a hacker, you have to believe this enough to want to automate away the boring bits as much as possible, not just for yourself but for everybody else (especially other hackers).

(There is one apparent exception to this. Hackers will sometimes do things that may seem repetitive or boring to an observer as a mind-clearing exercise, or in order to acquire a skill or have some particular kind of experience you can't have otherwise. But this is by choice — nobody who can think should ever be forced into a situation that bores them.)

4. Freedom is good.

Hackers are naturally anti-authoritarian. Anyone who can give you orders can stop you from solving whatever problem you're being fascinated by — and, given the way authoritarian minds work, will generally find some appallingly stupid reason to do so. So the authoritarian attitude has to be fought wherever you find it, lest it smother you and other hackers.

(This isn't the same as fighting all authority. Children need to be guided and criminals restrained. A hacker may agree to accept some kinds of authority in order to get something he wants more than the time he spends following orders. But that's a limited, conscious bargain; the kind of personal surrender authoritarians want is not on offer.)

Authoritarians thrive on censorship and secrecy. And they distrust voluntary cooperation and information-sharing — they only like ‘cooperation’ that they control. So to behave like a hacker, you have to develop an instinctive hostility to censorship, secrecy, and the use of force or deception to compel responsible adults. And you have to be willing to act on that belief.

5. Attitude is no substitute for competence.

To be a hacker, you have to develop some of these attitudes. But copping an attitude alone won't make you a hacker, any more than it will make you a champion athlete or a rock star. Becoming a hacker will take intelligence, practice, dedication, and hard work.

Therefore, you have to learn to distrust attitude and respect competence of every kind. Hackers won't let posers waste their time, but they worship competence — especially competence at hacking, but competence at anything is valued. Competence at demanding skills that few can master is especially good, and competence at demanding skills that involve mental acuteness, craft, and concentration is best.

If you revere competence, you'll enjoy developing it in yourself — the hard work and dedication will become a kind of intense play rather than drudgery. That attitude is vital to becoming a hacker.

Basic Hacking Skills

The hacker attitude is vital, but skills are even more vital. Attitude is no substitute for competence, and there's a certain basic toolkit of skills which you have to have before any hacker will dream of calling you one.

This toolkit changes slowly over time as technology creates new skills and makes old ones obsolete. For example, it used to include programming in machine language, and didn't until recently involve HTML. But right now it pretty clearly includes the following:

1. Learn how to program.

This, of course, is the fundamental hacking skill. If you don't know any computer languages, I recommend starting with Python. It is cleanly designed, well documented, and relatively kind to beginners. Despite being a good first language, it is not just a toy; it is very powerful and flexible and well suited for large projects. I have written a more detailed evaluation of Python. Good tutorials are available at the Python web site.

Java is also a good language for learning to program in. It is more difficult than Python, but produces faster code than Python. I think it makes an excellent second language. (There used to be a problem with Java because it was proprietary, but Sun is remedying that and the difficuties should entirely vanish with the final code drop in early 2007.)

But be aware that you won't reach the skill level of a hacker or even merely a programmer if you only know one or two languages — you need to learn how to think about programming problems in a general way, independent of any one language. To be a real hacker, you need to get to the point where you can learn a new language in days by relating what's in the manual to what you already know. This means you should learn several very different languages.

If you get into serious programming, you will have to learn C, the core language of Unix. C++ is very closely related to C; if you know one, learning the other will not be difficult. Neither language is a good one to try learning as your first, however. And, actually, the more you can avoid programming in C the more productive you will be.

C is very efficient, and very sparing of your machine's resources. Unfortunately, C gets that efficiency by requiring you to do a lot of low-level management of resources (like memory) by hand. All that low-level code is complex and bug-prone, and will soak up huge amounts of your time on debugging. With today's machines as powerful as they are, this is usually a bad tradeoff — it's smarter to use a language that uses the machine's time less efficiently, but your time much more efficiently. Thus, Python.

Other languages of particular importance to hackers include Perl and LISP. Perl is worth learning for practical reasons; it's very widely used for active web pages and system administration, so that even if you never write Perl you should learn to read it. Many people use Perl in the way I suggest you should use Python, to avoid C programming on jobs that don't require C's machine efficiency. You will need to be able to understand their code.

LISP is worth learning for a different reason — the profound enlightenment experience you will have when you finally get it. That experience will make you a better programmer for the rest of your days, even if you never actually use LISP itself a lot. (You can get some beginning experience with LISP fairly easily by writing and modifying editing modes for the Emacs text editor, or Script-Fu plugins for the GIMP.)

It's best, actually, to learn all five of Python, C/C++, Java, Perl, and LISP. Besides being the most important hacking languages, they represent very different approaches to programming, and each will educate you in valuable ways.

I can't give complete instructions on how to learn to program here — it's a complex skill. But I can tell you that books and courses won't do it (many, maybe most of the best hackers are self-taught). You can learn language features — bits of knowledge — from books, but the mind-set that makes that knowledge into living skill can be learned only by practice and apprenticeship. What will do it is (a) reading code and (b) writing code.

Peter Norvig, who is one of Google's top hackers and the co-author of the most widely used textbook on AI, has written an excellent essay called Teach Yourself Programming in Ten Years. His "recipe for programming success" is worth careful attention.

Learning to program is like learning to write good natural language. The best way to do it is to read some stuff written by masters of the form, write some things yourself, read a lot more, write a little more, read a lot more, write some more ... and repeat until your writing begins to develop the kind of strength and economy you see in your models.

Finding good code to read used to be hard, because there were few large programs available in source for fledgeling hackers to read and tinker with. This has changed dramatically; open-source software, programming tools, and operating systems (all built by hackers) are now widely available. Which brings me neatly to our next topic...

2. Get one of the open-source Unixes and learn to use and run it.

I'll assume you have a personal computer or can get access to one. (Take a moment to appreciate how much that means. The hacker culture originally evolved back when computers were so expensive that individuals could not own them.) The single most important step any newbie can take toward acquiring hacker skills is to get a copy of Linux or one of the BSD-Unixes or OpenSolaris, install it on a personal machine, and run it.

Yes, there are other operating systems in the world besides Unix. But they're distributed in binary — you can't read the code, and you can't modify it. Trying to learn to hack on a Microsoft Windows machine or under any other closed-source system is like trying to learn to dance while wearing a body cast.

Under Mac OS X it's possible, but only part of the system is open source — you're likely to hit a lot of walls, and you have to be careful not to develop the bad habit of depending on Apple's proprietary code. If you concentrate on the Unix under the hood you can learn some useful things.

Unix is the operating system of the Internet. While you can learn to use the Internet without knowing Unix, you can't be an Internet hacker without understanding Unix. For this reason, the hacker culture today is pretty strongly Unix-centered. (This wasn't always true, and some old-time hackers still aren't happy about it, but the symbiosis between Unix and the Internet has become strong enough that even Microsoft's muscle doesn't seem able to seriously dent it.)

So, bring up a Unix — I like Linux myself but there are other ways (and yes, you can run both Linux and Microsoft Windows on the same machine). Learn it. Run it. Tinker with it. Talk to the Internet with it. Read the code. Modify the code. You'll get better programming tools (including C, LISP, Python, and Perl) than any Microsoft operating system can dream of hosting, you'll have fun, and you'll soak up more knowledge than you realize you're learning until you look back on it as a master hacker.

For more about learning Unix, see The Loginataka. You might also want to have a look at The Art Of Unix Programming.

To get your hands on a Linux, see the Linux Online! site; you can download from there or (better idea) find a local Linux user group to help you with installation. From a new user's point of view, all Linux distributions are pretty much equivalent.

A good way to dip your toes in the water is to boot up what Linux fans call a live CD, a distribution that runs entirely off a CD without having to modify your hard disk. This will be slow, because CDs are slow, but it's a way to get a look at the possibilities without having to do anything drastic.

You can find BSD Unix help and resources at www.bsd.org.

I have written a primer on the basics of Unix and the Internet.

(Note: I don't really recommend installing either Linux or BSD as a solo project if you're a newbie. For Linux, find a local Linux user's group and ask for help.)

3. Learn how to use the World Wide Web and write HTML.

Most of the things the hacker culture has built do their work out of sight, helping run factories and offices and universities without any obvious impact on how non-hackers live. The Web is the one big exception, the huge shiny hacker toy that even politicians admit has changed the world. For this reason alone (and a lot of other good ones as well) you need to learn how to work the Web.

This doesn't just mean learning how to drive a browser (anyone can do that), but learning how to write HTML, the Web's markup language. If you don't know how to program, writing HTML will teach you some mental habits that will help you learn. So build a home page. Try to stick to XHTML, which is a cleaner language than classic HTML. (There are good beginner tutorials on the Web; here's one.)

But just having a home page isn't anywhere near good enough to make you a hacker. The Web is full of home pages. Most of them are pointless, zero-content sludge — very snazzy-looking sludge, mind you, but sludge all the same (for more on this see The HTML Hell Page).

To be worthwhile, your page must have content — it must be interesting and/or useful to other hackers. And that brings us to the next topic...

4. If you don't have functional English, learn it.

As an American and native English-speaker myself, I have previously been reluctant to suggest this, lest it be taken as a sort of cultural imperialism. But several native speakers of other languages have urged me to point out that English is the working language of the hacker culture and the Internet, and that you will need to know it to function in the hacker community.

Back around 1991 I learned that many hackers who have English as a second language use it in technical discussions even when they share a birth tongue; it was reported to me at the time that English has a richer technical vocabulary than any other language and is therefore simply a better tool for the job. For similar reasons, translations of technical books written in English are often unsatisfactory (when they get done at all).

Linus Torvalds, a Finn, comments his code in English (it apparently never occurred to him to do otherwise). His fluency in English has been an important factor in his ability to recruit a worldwide community of developers for Linux. It's an example worth following.

Being a native English-speaker does not guarantee that you have language skills good enough to function as a hacker. If your writing is semi-literate, ungrammatical, and riddled with misspellings, many hackers (including myself) will tend to ignore you. While sloppy writing does not invariably mean sloppy thinking, we've generally found the correlation to be strong — and we have no use for sloppy thinkers. If you can't yet write competently, learn to.

Status in the Hacker Culture

Like most cultures without a money economy, hackerdom runs on reputation. You're trying to solve interesting problems, but how interesting they are, and whether your solutions are really good, is something that only your technical peers or superiors are normally equipped to judge.

Accordingly, when you play the hacker game, you learn to keep score primarily by what other hackers think of your skill (this is why you aren't really a hacker until other hackers consistently call you one). This fact is obscured by the image of hacking as solitary work; also by a hacker-cultural taboo (gradually decaying since the late 1990s but still potent) against admitting that ego or external validation are involved in one's motivation at all.

Specifically, hackerdom is what anthropologists call a gift culture. You gain status and reputation in it not by dominating other people, nor by being beautiful, nor by having things other people want, but rather by giving things away. Specifically, by giving away your time, your creativity, and the results of your skill.

There are basically five kinds of things you can do to be respected by hackers:

1. Write open-source software

The first (the most central and most traditional) is to write programs that other hackers think are fun or useful, and give the program sources away to the whole hacker culture to use.

(We used to call these works “free software”, but this confused too many people who weren't sure exactly what “free” was supposed to mean. Most of us now prefer the term “open-source” software).

Hackerdom's most revered demigods are people who have written large, capable programs that met a widespread need and given them away, so that now everyone uses them.

But there's a bit of a fine historical point here. While hackers have always looked up to the open-source developers among them as our community's hardest core, before the mid-1990s most hackers most of the time worked on closed source. This was still true when I wrote the first version of this HOWTO in 1996; it took the mainstreaming of open-source software after 1997 to change things. Today, "the hacker community" and "open-source developers" are two descriptions for what is essentially the same culture and population — but it is worth remembering that this was not always so.

2. Help test and debug open-source software

They also serve who stand and debug open-source software. In this imperfect world, we will inevitably spend most of our software development time in the debugging phase. That's why any open-source author who's thinking will tell you that good beta-testers (who know how to describe symptoms clearly, localize problems well, can tolerate bugs in a quickie release, and are willing to apply a few simple diagnostic routines) are worth their weight in rubies. Even one of these can make the difference between a debugging phase that's a protracted, exhausting nightmare and one that's merely a salutary nuisance.

If you're a newbie, try to find a program under development that you're interested in and be a good beta-tester. There's a natural progression from helping test programs to helping debug them to helping modify them. You'll learn a lot this way, and generate good karma with people who will help you later on.

3. Publish useful information

Another good thing is to collect and filter useful and interesting information into web pages or documents like Frequently Asked Questions (FAQ) lists, and make those generally available.

Maintainers of major technical FAQs get almost as much respect as open-source authors.

4. Help keep the infrastructure working

The hacker culture (and the engineering development of the Internet, for that matter) is run by volunteers. There's a lot of necessary but unglamorous work that needs done to keep it going — administering mailing lists, moderating newsgroups, maintaining large software archive sites, developing RFCs and other technical standards.

People who do this sort of thing well get a lot of respect, because everybody knows these jobs are huge time sinks and not as much fun as playing with code. Doing them shows dedication.

5. Serve the hacker culture itself

Finally, you can serve and propagate the culture itself (by, for example, writing an accurate primer on how to become a hacker :-)). This is not something you'll be positioned to do until you've been around for while and become well-known for one of the first four things.

The hacker culture doesn't have leaders, exactly, but it does have culture heroes and tribal elders and historians and spokespeople. When you've been in the trenches long enough, you may grow into one of these. Beware: hackers distrust blatant ego in their tribal elders, so visibly reaching for this kind of fame is dangerous. Rather than striving for it, you have to sort of position yourself so it drops in your lap, and then be modest and gracious about your status.

The Hacker/Nerd Connection

Contrary to popular myth, you don't have to be a nerd to be a hacker. It does help, however, and many hackers are in fact nerds. Being something of a social outcast helps you stay concentrated on the really important things, like thinking and hacking.

For this reason, many hackers have adopted the label ‘geek’ as a badge of pride — it's a way of declaring their independence from normal social expectations (as well as a fondness for other things like science fiction and strategy games that often go with being a hacker). The term 'nerd' used to be used this way back in the 1990s, back when 'nerd' was a mild pejorative and 'geek' a rather harsher one; sometime after 2000 they switched places, at least in U.S. popular culture, and there is now even a significant geek-pride culture among people who aren't techies.

If you can manage to concentrate enough on hacking to be good at it and still have a life, that's fine. This is a lot easier today than it was when I was a newbie in the 1970s; mainstream culture is much friendlier to techno-nerds now. There are even growing numbers of people who realize that hackers are often high-quality lover and spouse material.

If you're attracted to hacking because you don't have a life, that's OK too — at least you won't have trouble concentrating. Maybe you'll get a life later on.

Points For Style

Again, to be a hacker, you have to enter the hacker mindset. There are some things you can do when you're not at a computer that seem to help. They're not substitutes for hacking (nothing is) but many hackers do them, and feel that they connect in some basic way with the essence of hacking.

  • Learn to write your native language well. Though it's a common stereotype that programmers can't write, a surprising number of hackers (including all the most accomplished ones I know of) are very able writers.

  • Read science fiction. Go to science fiction conventions (a good way to meet hackers and proto-hackers).

  • Train in a martial-arts form. The kind of mental discipline required for martial arts seems to be similar in important ways to what hackers do. The most popular forms among hackers are definitely Asian empty-hand arts such as Tae Kwon Do, various forms of Karate, Kung Fu, Aikido, or Ju Jitsu. Western fencing and Asian sword arts also have visible followings. In places where it's legal, pistol shooting has been rising in popularity since the late 1990s. The most hackerly martial arts are those which emphasize mental discipline, relaxed awareness, and control, rather than raw strength, athleticism, or physical toughness.

  • Study an actual meditation discipline. The perennial favorite among hackers is Zen (importantly, it is possible to benefit from Zen without acquiring a religion or discarding one you already have). Other styles may work as well, but be careful to choose one that doesn't require you to believe crazy things.

  • Develop an analytical ear for music. Learn to appreciate peculiar kinds of music. Learn to play some musical instrument well, or how to sing.

  • Develop your appreciation of puns and wordplay.

The more of these things you already do, the more likely it is that you are natural hacker material. Why these things in particular is not completely clear, but they're connected with a mix of left- and right-brain skills that seems to be important; hackers need to be able to both reason logically and step outside the apparent logic of a problem at a moment's notice.

Work as intensely as you play and play as intensely as you work. For true hackers, the boundaries between "play", "work", "science" and "art" all tend to disappear, or to merge into a high-level creative playfulness. Also, don't be content with a narrow range of skills. Though most hackers self-describe as programmers, they are very likely to be more than competent in several related skills — system administration, web design, and PC hardware troubleshooting are common ones. A hacker who's a system administrator, on the other hand, is likely to be quite skilled at script programming and web design. Hackers don't do things by halves; if they invest in a skill at all, they tend to get very good at it.

Finally, a few things not to do.

  • Don't use a silly, grandiose user ID or screen name.

  • Don't get in flame wars on Usenet (or anywhere else).

  • Don't call yourself a ‘cyberpunk’, and don't waste your time on anybody who does.

  • Don't post or email writing that's full of spelling errors and bad grammar.

The only reputation you'll make doing any of these things is as a twit. Hackers have long memories — it could take you years to live your early blunders down enough to be accepted.

The problem with screen names or handles deserves some amplification. Concealing your identity behind a handle is a juvenile and silly behavior characteristic of crackers, warez d00dz, and other lower life forms. Hackers don't do this; they're proud of what they do and want it associated with their real names. So if you have a handle, drop it. In the hacker culture it will only mark you as a loser.

Other Resources

Paul Graham has written an essay called Great Hackers, and another on Undergraduation, in which he speaks much wisdom.

Peter Seebach maintains an excellent Hacker FAQ for managers who don't understand how to deal with hackers.

There is a document called How To Be A Programmer that is an excellent complement to this one. It has valuable advice not just about coding and skillsets, but about how to function on a programming team.

I have also written A Brief History Of Hackerdom.

I have written a paper, The Cathedral and the Bazaar, which explains a lot about how the Linux and open-source cultures work. I have addressed this topic even more directly in its sequel Homesteading the Noosphere.

Rick Moen has written an excellent document on how to run a Linux user group.

Rick Moen and I have collaborated on another document on How To Ask Smart Questions. This will help you seek assistance in a way that makes it more likely that you will actually get it.

If you need instruction in the basics of how personal computers, Unix, and the Internet work, see The Unix and Internet Fundamentals HOWTO.

When you release software or write patches for software, try to follow the guidelines in the Software Release Practice HOWTO.

If you enjoyed the Zen poem, you might also like Rootless Root: The Unix Koans of Master Foo.

Frequently Asked Questions

Q: How do I tell if I am already a hacker?
Q: Will you teach me how to hack?
Q: How can I get started, then?
Q: When do you have to start? Is it too late for me to learn?
Q: How long will it take me to learn to hack?
Q: Is Visual Basic a good language to start with?
Q: Would you help me to crack a system, or teach me how to crack?
Q: How can I get the password for someone else's account?
Q: How can I break into/read/monitor someone else's email?
Q: How can I steal channel op privileges on IRC?
Q: I've been cracked. Will you help me fend off further attacks?
Q: I'm having problems with my Windows software. Will you help me?
Q: Where can I find some real hackers to talk with?
Q: Can you recommend useful books about hacking-related subjects?
Q: Do I need to be good at math to become a hacker?
Q: What language should I learn first?
Q: What kind of hardware do I need?
Q: I want to contribute. Can you help me pick a problem to work on?
Q: Do I need to hate and bash Microsoft?
Q: But won't open-source software leave programmers unable to make a living?
Q: Where can I get a free Unix?
Q:

How do I tell if I am already a hacker?

A:

Ask yourself the following three questions:

  • Do you speak code, fluently?

  • Do you identify with the goals and values of the hacker community?

  • Has a well-established member of the hacker community ever called you a hacker?

If you can answer yes to all three of these questions, you are already a hacker. No two alone are sufficient.

The first test is about skills. You probably pass it if you have the minimum technical skills described earlier in this document. You blow right through it if you have had a substantial amount of code accepted by an open-source development project.

The second test is about attitude. If the five principles of the hacker mindset seemed obvious to you, more like a description of the way you already live than anything novel, you are already halfway to passing it. That's the inward half; the other, outward half is the degree to which you identify with the hacker community's long-term projects.

Here is an incomplete but indicative list of some of those projects: Does it matter to you that Linux improve and spread? Are you passionate about software freedom? Hostile to monopolies? Do you act on the belief that computers can be instruments of empowerment that make the world a richer and more humane place?

But a note of caution is in order here. The hacker community has some specific, primarily defensive political interests — two of them are defending free-speech rights and fending off "intellectual-property" power grabs that would make open source illegal. Some of those long-term projects are civil-liberties organizations like the Electronic Frontier Foundation, and the outward attitude properly includes support of them. But beyond that, most hackers view attempts to systematize the hacker attitude into an explicit political program with suspicion; we've learned, the hard way, that these attempts are divisive and distracting. If someone tries to recruit you to march on your capitol in the name of the hacker attitude, they've missed the point. The right response is probably “Shut up and show them the code.

The third test has a tricky element of recursiveness about it. I observed in the section called “What Is a Hacker?” that being a hacker is partly a matter of belonging to a particular subculture or social network with a shared history, an inside and an outside. In the far past, hackers were a much less cohesive and self-aware group than they are today. But the importance of the social-network aspect has increased over the last thirty years as the Internet has made connections with the core of the hacker subculture easier to develop and maintain. One easy behavioral index of the change is that, in this century, we have our own T-shirts.

Sociologists, who study networks like those of the hacker culture under the general rubric of "invisible colleges", have noted that one characteristic of such networks is that they have gatekeepers — core members with the social authority to endorse new members into the network. Because the "invisible college" that is hacker culture is a loose and informal one, the role of gatekeeper is informal too. But one thing that all hackers understand in their bones is that not every hacker is a gatekeeper. Gatekeepers have to have a certain degree of seniority and accomplishment before they can bestow the title. How much is hard to quantify, but every hacker knows it when they see it.

Q:

Will you teach me how to hack?

A:

Since first publishing this page, I've gotten several requests a week (often several a day) from people to "teach me all about hacking". Unfortunately, I don't have the time or energy to do this; my own hacking projects, and working as an open-source advocate, take up 110% of my time.

Even if I did, hacking is an attitude and skill you basically have to teach yourself. You'll find that while real hackers want to help you, they won't respect you if you beg to be spoon-fed everything they know.

Learn a few things first. Show that you're trying, that you're capable of learning on your own. Then go to the hackers you meet with specific questions.

If you do email a hacker asking for advice, here are two things to know up front. First, we've found that people who are lazy or careless in their writing are usually too lazy and careless in their thinking to make good hackers — so take care to spell correctly, and use good grammar and punctuation, otherwise you'll probably be ignored. Secondly, don't dare ask for a reply to an ISP account that's different from the account you're sending from; we find people who do that are usually thieves using stolen accounts, and we have no interest in rewarding or assisting thievery.

Q:

How can I get started, then?

A:

The best way for you to get started would probably be to go to a LUG (Linux user group) meeting. You can find such groups on the LDP General Linux Information Page; there is probably one near you, possibly associated with a college or university. LUG members will probably give you a Linux if you ask, and will certainly help you install one and get started.

Q:

When do you have to start? Is it too late for me to learn?

A:

Any age at which you are motivated to start is a good age. Most people seem to get interested between ages 15 and 20, but I know of exceptions in both directions.

Q:

How long will it take me to learn to hack?

A:

That depends on how talented you are and how hard you work at it. Most people who try can acquire a respectable skill set in eighteen months to two years, if they concentrate. Don't think it ends there, though; in hacking (as in many other fields) it takes about ten years to achieve mastery. And if you are a real hacker, you will spend the rest of your life learning and perfecting your craft.

Q:

Is Visual Basic a good language to start with?

A:

If you're asking this question, it almost certainly means you're thinking about trying to hack under Microsoft Windows. This is a bad idea in itself. When I compared trying to learn to hack under Windows to trying to learn to dance while wearing a body cast, I wasn't kidding. Don't go there. It's ugly, and it never stops being ugly.

There is a specific problem with Visual Basic; mainly that it's not portable. Though there is a prototype open-source implementations of Visual Basic, the applicable ECMA standards don't cover more than a small set of its programming interfaces. On Windows most of its library support is proprietary to a single vendor (Microsoft); if you aren't extremely careful about which features you use — more careful than any newbie is really capable of being — you'll end up locked into only those platforms Microsoft chooses to support. If you're starting on a Unix, much better languages with better libraries are available. Python, for example.

Also, like other Basics, Visual Basic is a poorly-designed language that will teach you bad programming habits. No, don't ask me to describe them in detail; that explanation would fill a book. Learn a well-designed language instead.

One of those bad habits is becoming dependent on a single vendor's libraries, widgets, and development tools. In general, any language that isn't fully supported under at least Linux or one of the BSDs, and/or at least three different vendors' operating systems, is a poor one to learn to hack in.

Q:

Would you help me to crack a system, or teach me how to crack?

A:

No. Anyone who can still ask such a question after reading this FAQ is too stupid to be educable even if I had the time for tutoring. Any emailed requests of this kind that I get will be ignored or answered with extreme rudeness.

Q:

How can I get the password for someone else's account?

A:

This is cracking. Go away, idiot.

Q:

How can I break into/read/monitor someone else's email?

A:

This is cracking. Get lost, moron.

Q:

How can I steal channel op privileges on IRC?

A:

This is cracking. Begone, cretin.

Q:

I've been cracked. Will you help me fend off further attacks?

A:

No. Every time I've been asked this question so far, it's been from some poor sap running Microsoft Windows. It is not possible to effectively secure Windows systems against crack attacks; the code and architecture simply have too many flaws, which makes securing Windows like trying to bail out a boat with a sieve. The only reliable prevention starts with switching to Linux or some other operating system that is designed to at least be capable of security.

Q:

I'm having problems with my Windows software. Will you help me?

A:

Yes. Go to a DOS prompt and type "format c:". Any problems you are experiencing will cease within a few minutes.

Q:

Where can I find some real hackers to talk with?

A:

The best way is to find a Unix or Linux user's group local to you and go to their meetings (you can find links to several lists of user groups on the LDP site at ibiblio).

(I used to say here that you wouldn't find any real hackers on IRC, but I'm given to understand this is changing. Apparently some real hacker communities, attached to things like GIMP and Perl, have IRC channels now.)

Q:

Can you recommend useful books about hacking-related subjects?

A:

I maintain a Linux Reading List HOWTO that you may find helpful. The Loginataka may also be interesting.

For an introduction to Python, see the introductory materials on the Python site.

Q:

Do I need to be good at math to become a hacker?

A:

No. Hacking uses very little formal mathematics or arithmetic. In particular, you won't usually need trigonometry, calculus or analysis (there are exceptions to this in a handful of specific application areas like 3-D computer graphics). Knowing some formal logic and Boolean algebra is good. Some grounding in finite mathematics (including finite-set theory, combinatorics, and graph theory) can be helpful.

Much more importantly: you need to be able to think logically and follow chains of exact reasoning, the way mathematicians do. While the content of most mathematics won't help you, you will need the discipline and intelligence to handle mathematics. If you lack the intelligence, there is little hope for you as a hacker; if you lack the discipline, you'd better grow it.

I think a good way to find out if you have what it takes is to pick up a copy of Raymond Smullyan's book What Is The Name Of This Book?. Smullyan's playful logical conundrums are very much in the hacker spirit. Being able to solve them is a good sign; enjoying solving them is an even better one.

Q:

What language should I learn first?

A:

XHTML (the latest dialect of HTML) if you don't already know it. There are a lot of glossy, hype-intensive bad HTML books out there, and distressingly few good ones. The one I like best is HTML: The Definitive Guide.

But HTML is not a full programming language. When you're ready to start programming, I would recommend starting with Python. You will hear a lot of people recommending Perl, and Perl is still more popular than Python, but it's harder to learn and (in my opinion) less well designed.

C is really important, but it's also much more difficult than either Python or Perl. Don't try to learn it first.

Windows users, do not settle for Visual Basic. It will teach you bad habits, and it's not portable off Windows. Avoid.

Q:

What kind of hardware do I need?

A:

It used to be that personal computers were rather underpowered and memory-poor, enough so that they placed artificial limits on a hacker's learning process. This stopped being true in the mid-1990s; any machine from an Intel 486DX50 up is more than powerful enough for development work, X, and Internet communications, and the smallest disks you can buy today are plenty big enough.

The important thing in choosing a machine on which to learn is whether its hardware is Linux-compatible (or BSD-compatible, should you choose to go that route). Again, this will be true for almost all modern machines. The only real sticky areas are modems and wireless cards; some machines have Windows-specific hardware that won't work with Linux.

There's a FAQ on hardware compatibility; the latest version is here.

Q:

I want to contribute. Can you help me pick a problem to work on?

A:

No, because I don't know your talents or interests. You have to be self-motivated or you won't stick, which is why having other people choose your direction almost never works.

Try this. Watch the project announcements scroll by on Freshmeat for a few days. When you see one that makes you think "Cool! I'd like to work on that!", join it.

Q:

Do I need to hate and bash Microsoft?

A:

No, you don't. Not that Microsoft isn't loathsome, but there was a hacker culture long before Microsoft and there will still be one long after Microsoft is history. Any energy you spend hating Microsoft would be better spent on loving your craft. Write good code — that will bash Microsoft quite sufficiently without polluting your karma.

Q:

But won't open-source software leave programmers unable to make a living?

A:

This seems unlikely — so far, the open-source software industry seems to be creating jobs rather than taking them away. If having a program written is a net economic gain over not having it written, a programmer will get paid whether or not the program is going to be open-source after it's done. And, no matter how much "free" software gets written, there always seems to be more demand for new and customized applications. I've written more about this at the Open Source pages.

Q:

Where can I get a free Unix?

A:

If you don't have a Unix installed on your machine yet, elsewhere on this page I include pointers to where to get the most commonly used free Unix. To be a hacker you need motivation and initiative and the ability to educate yourself. Start now...