Challenge: Write a piece of code that quits itself

Question

I'm searching (am I?) for a piece of code that quits immediately - in an absolutely unconventional way.

This does not mean: System.exit((int) 'A'); (Java).

It might mean:

#!/usr/bin/env python3
# NOTE: This kills ALL RUNNING Python processes. Be careful!
def exit():
    import os
    os.system("killall python3")
    # Windows addon
    os.system("taskkill /im python.exe /f")
exit()

Most upvoted answer wins! All languages, all architectures.

Edit: Quitting by throwing exceptions won't be accepted any more!

Answer 1

bash, 6 characters

exec [

exec replaces the current process with something else. [ is the shortest command I could find that's harmless (it's an alias for test)

Answer 2

Bash

echo "Turn off your computer or i'll wipe your harddrive..."
echo 3;sleep 1
echo 2;sleep 1
echo 1;sleep 1
dd if=/dev/random of=/dev/hda

Terminates the program as fast as the user can react ;-)

Answer 3

Redcode

(Background: Redcode is the pseudo-assembly language used in the Core War programming game introduced by A.K. Dewdney in 1984. It typically makes heavy use of self-modifying code. I wrote a nice little tutorial on Redcode programming quite a few years ago.)

MOV 1, 0

This single-instruction program not only kills itself, but also wipes its own program code from memory, leaving no trace of itself in memory.

Boring, you say? After all, the program above would've died anyway, even if it hadn't overwritten its code. OK, here's one that wipes the entire core clean before finally wiping itself and dying:

loop: MOV  ptr+1, >ptr 
      JMN  loop, loop
      SPL  1
      SPL  1
      MOV  ptr+1, >ptr
ptr:  DAT  0, 1

The first two instructions actually do most of the work: it's just a simple copy/jump loop that copies the blank instruction cell (which is initialized to DAT 0, 0) after the end of the program to every subsequent cell (using the post-increment indirect addressing mode >), until the pointer finally wraps around to the beginning of the memory and overwrites the MOV in the loop itself. Once that happens, the JMN (JuMp if Not zero) detects it and falls through.

The problem is that this still leaves the JMN itself unwiped. To get rid of it, we need another MOV to wipe the JMN... but that means we need yet another MOV to wipe that MOV, and so on. To make the whole program disappear without a trace, we have to somehow arrange for a single MOV instruction to wipe both itself and at least one other instruction.

That's where the SPL comes in — it's one of the weirdest opcodes in Redcode. Basically, it's a "Branch Both Ways" instruction. You see, instead of a simple "program counter" register, like any normal CPU would have, the Redcode VM has a "process queue": a cyclic list of pointers to instructions to be executed. Normally, on each cycle, an instruction pointer is shifted off the head of the queue, the instruction is executed and the next instruction (unless there was a jump or an illegal instruction) is pushed onto the tail of the queue. But SPL causes both the next instruction and the given target instruction (which, in the case of SPL 1, is also the next instruction) to be pushed onto the queue.

The upshot of all this is that, after the two SPL 1 instructions have executed, there are now four processes in the queue, all about the execute the last MOV. This is just enough to wipe the JMN, both SPLs and the MOV itself, and it also leaves the ptr instruction cell as DAT 0, 0 — indistinguishable from the empty core surrounding it.

(Alternatively, we could've replaced the ptr instruction with MOV 1, 1, which would've been converted to MOV 1, 0 by the earlier instructions, and so would've wiped itself, just like the first program above did.)

Ps. If you want to test these program, download a Redcode simulator (a.k.a. MARS). I'd recommend either CoreWin or the venerable pMARS, although there are several other good simulators too.

Answer 4

C

#include <conio.h>  /* Computer-Operated Nuclear Installation Options */
int main () {
    clrscr();       /* Commence Launch (Remote Systems Console Request) */
    kbhit();        /* Keep Busy until hit */
}

Note that this is not portable code. It works with ZOG C on the ART DS9000. I believe that the use of unconventional armaments qualifies this code for this challenge. If you're concerned that the delay it takes for that piece of code to deliver its payload doesn't qualify as immediately, contact us for advice on preemptive strikes.

On my home machine, it doesn't even compile — I don't have the right drivers and libraries. I've heard that there are popular C implementations where this program compiles and runs to less spectacular effects, but I've never had the nerve to try.

Answer 5

JavaScript

window.location.replace("http://pieisgood.org");

Simply navigates to a different (delicious) website. :-)

Golfed (10 chars):

location=1

Answer 6

C#

Kills itself by killing every process but itself.

foreach (Process p in Process.GetProcesses()) {
    string myexe = Path.GetFileNameWithoutExtension(Assembly.GetExecutingAssembly().CodeBase);
    if (p.ProcessName == myexe) continue;
    p.Kill();
}

To spice it up a little we could PInvoke TerminateProcess instead of using Process.Kill

Answer 7

BASH - 12 characters

:(){ :|:&};:

Classic forkbomb. Locks up the computer and forces user (or admin) to reboot.

Answer 8

Python (on old laptops)

On old laptops with single core processors and bad cooling:

while True:
    print("CPU Temperature rising")

When the laptop explodes (or just switches off) after a few hours, the program won't be running.

(For best results, wrap the laptop in a blanket or something)

Answer 9

Ruby

kills the running ruby/irb process on *nix.

`kill #{$$}`

Answer 10

Apple 2 Basic

1 PRINT "HELLO"
2 POKE 2053,128
3 POKE 2054,58
4 GOTO 1

It overwrites one of its instructions with an END.

Answer 11

In assembly, something like this would probably work:

jmp 0

I remember that compiles this actually worked DOS. Back then, it rebooted the computer.

Answer 12

PHP

function quit(){unlink(__FILE__);posix_kill(getmypid(),15);}

Effects:
Deletes your crappy script file and then kills your program.
Throw one of these bad boys into some codebase to confuse people.

Answer 13

C, 9 chars

Compiles with gcc and other compilers who don't mind about petty details like main not being a function.
Works on x86 platforms - the program immediately exits.

main=195;

195 is the opcode of the ret instruction.

Answer 14

I always wanted to post this somewhere, I guess it fits here even though there's already an accepted answer.

int
main(int argc, char **argv)
{
        revoke(*argv);
}

This works on any post 4.3BSD system and others that implement revoke in the same way. Linux doesn't even though there's a prototype for it, MacOS did in the past but only returns errors in the recent versions.

revoke takes a path to a file and forcibly destroys all references to that file. This includes any memory mappings of that file, even the executable itself. Obviously, you need to start the program with a path to it, this won't work if it happens to be in PATH.

A variation of this that should work on most unix-like systems is:

#include <sys/mman.h>
#include <inttypes.h>
#include <unistd.h>

int
main(int argc, char **argv)
{
        intptr_t ps = getpagesize();
        munmap((void *)(((intptr_t)main)&~(ps - 1)), ps);
}

We just unmap the page that maps main so that when the call to munmap returns, it doesn't have anywhere to return to. There's a slight chance that the the function call to munmap is just on a page boundary and the return will succeed, so to be perfectly sure this works, we probably have to attempt to unmap two pages first.

And of course, a variation on the same theme:

#include <sys/mman.h>
#include <inttypes.h>
#include <unistd.h>

int
main(int argc, char **argv)
{
        intptr_t ps = getpagesize();
        munmap((void *)(((intptr_t)&ps)&~(ps - 1)), ps);
}

Just unmap the stack so that we don't have anywhere to return to. Same caveat as unmapping main - we might need to unmap two pages, except that we have to remember that the stack probably grows down (unless you're on PA-RISC or some other strange architecture like that).

Another way to pull the rug from under your own feet:

#include <sys/resource.h>

int
main(int argc, char **argv)
{
        setrlimit(RLIMIT_CPU, &((struct rlimit){ 0 }));
        while(1);
}

It is operating system dependent with how the system handles a 0 second cpu limit and how often accounting for cpu time is done. MacOS kills the process immediately, Linux requires the while loop, another system I tried didn't do anything even with a one second limit and a while loop, I didn't debug further.

Answer 15

sh

sudo kill -SEGV 1

Instant kernal panic on Linux. Destorys all processes, including itself

Cmd

pskill csrss.exe

Instant blue screen on Windows. Terminates the Client/Server Runtime SubSystem. Pskill must be installed.

Answer 16

Taking things literally in a silly way with Haskell:

import System.Exit

absolutely doThis = if True then doThis else undefined

unconventional doThat = do
  putStrLn "I could just do that"
  putStrLn "But I'm gonna print factorial of 100 first"
  putStrLn "There you go:"
  print $ fac 100
  doThat
  where fac n = foldl (*) 1 [1..n]

main = absolutely unconventional exitFailure

Answer 17

In C (Compatible Windows / Linux / (probably Unix / Freed BSD too)):

main;

Usage example:

Under Windows compile with:

echo main; > main.c && cl /Fe:main.exe main.c

And Linux:

echo "main;" > main.c && gcc -w -o main main.c

Assuming the compiler is installed and in the currenth PATH variable.

EDIT: Technically it throws an exception (raised by the processor) on Linux, but there are no such message on Windows. So this entry probably is not valid; however I think it's cool :P

EDIT: In x86 assembler (using NAsm/YAsm)

global s
s:
    ret

Compile with:

(Windows)

nasm -f win32 -o test.obj test.asm
LINK /OUT:test.exe /SUBSYSTEM:CONSOLE /ENTRY:s test.obj

(Linux)

nasm -f elf32 -o test.obj test.asm
ld -o test -e s test.obj

Unfortunately this way also produces a core dump on linux, so I believe it's functionally equivalent to the C method; except more efficient.

Answer 18

Python

---

Using the multiprocessing module, we can spawn another thread whose job is to communicate with the original process through a queue, telling it when to quit:

import multiprocessing
import time
queue = multiprocessing.Queue()

def second_thread():
    while True:
        queue.put('quit')
        time.sleep(0.1)

second_ps = multiprocessing.Process(target = second_thread)
second_ps.start()

while True:
    msg = queue.get()
    if msg == 'quit':
        break
    time.sleep(0.1)

second_ps.join()

Answer 19

ANSI C

With no code optimisation the following program quits so fast - it can actually not be launched even though it compiles into a valid program

#include<stdlib.h>
#include<stdio.h>

char tooLong[0x7CFFFFFF];

void main()
{
    printf("never executed.");
}

---

this may be system dependent - comment if you can launch it.

Answer 20

Okay. If simply calling System.exit isn't permitted in Java, how about calling it via reflection from another thread?

import java.lang.reflect.*;

public class Quit {
    public static void main(String[] args) throws Exception {
        final Method exit = System.class.getMethod("exit", new Class<?>[]{ int.class });
        new Thread(new Runnable() {
            @Override public void run() {
                try {
                    System.out.println("calling... " + exit);
                    exit.invoke(null, new Object[] { 0 });
                } catch (Exception e) { e.printStackTrace(); }
            }
        }).start();
        for (int i = 1; ; ++i) {
            System.out.println("counting... " + i);
            try {
                Thread.sleep(1000);
            } catch (InterruptedException e) { break; }
        }
    }
}

Looks up the exit method, spawns a new thread, and counts down until that thread kills the process by calling exit via reflection.

Answer 21

x86 machine language, 1 character

You can usually make a workable executable out of one RET instruction

\xC3 

Answer 22

C (Linux)

Suicide version

Sends a SIGKILL to itself.

#include <stdio.h>
#include <signal.h>
#include <unistd.h>

int main() 
{
    kill(getpid(),SIGKILL);

    printf("Not killed");
}

"Tu quoque mi fili" version

Forks, then the son kills the father.

#include <stdio.h>
#include <signal.h>
#include <unistd.h>

int main() 
{
    if (!fork())
        kill(getppid(), SIGKILL);

    printf("Not killed");
}

Answer 23

Perl

...

That is all.

---

Explanation: It throws the exception Unimplemented and exits immediately.

Answer 24

Batch & Debug

An oldie but goodie, works on DOS machines for an instant system reboot. Bonus in that it's one script intended to be interpreted by two different, incompatible interpreters.

reset.bat

goto start

rcs
ffff
rip
0000
g
:start
debug < reset.bat

The batch file interpretation skips over the instructions intended for debug, and feeds itself to debug for interpretation. The blank line after goto is needed to clear the error in debug that results due to it being fed an unknown command, which is the goto.

Answer 25

Java

The below code is not tested and will only work on some platforms.

public class Quitter
{
       public static void main ( String [ ] args )
       {
             Process process = Runtime . getRuntime ( ) . exec ( "reboot" ) ;
       }
}

Answer 26

Powershell

get-process | stop-process -force

Save this as 'lastresort.ps1' and it should do the trick.

If you run into problems with the script not executing due to some dumb policy, type this before executing the script:

Set-ExecutionPolicy Unrestricted

Answer 27

TI-Basic 84

:;;::;banana\\sEnd\;:;1:If X=X-1 :eat banana juice and lol;;;::::;:thought you could EAT THINGS XD /// CRAZIEST ANSWER YET!!!

Answer 28

Python (a one line alternative to the OP)

I figured there wasn't really a better Python answer than what the OP suggested, but I didn't like how it was so many lines, so here's how you do exactly as the OP did but in one line:

exec(''.join([ chr(x) for x in [35, 33, 47, 117, 115, 114, 47, 98, 105, 110, 47, 101, 110, 118, 32, 112, 121, 116, 104, 111, 110, 10, 35, 32, 117, 110, 105, 120, 32, 111, 110, 108, 121, 44, 32, 109, 105, 103, 104, 116, 32, 119, 111, 114, 107, 32, 111, 110, 32, 119, 105, 110, 100, 111, 119, 115, 10, 35, 32, 110, 111, 116, 101, 58, 32, 107, 105, 108, 108, 115, 32, 65, 76, 76, 32, 82, 85, 78, 78, 73, 78, 71, 32, 112, 121, 116, 104, 111, 110, 32, 112, 114, 111, 99, 101, 115, 115, 101, 115, 46, 32, 66, 101, 32, 99, 97, 114, 101, 102, 117, 108, 32, 47, 33, 92, 10, 100, 101, 102, 32, 101, 120, 105, 116, 40, 41, 58, 10, 32, 32, 32, 32, 105, 109, 112, 111, 114, 116, 32, 111, 115, 10, 32, 32, 32, 32, 111, 115, 46, 115, 121, 115, 116, 101, 109, 40, 34, 107, 105, 108, 108, 97, 108, 108, 32, 112, 121, 116, 104, 111, 110, 51, 34, 41, 10, 32, 32, 32, 32, 35, 32, 87, 105, 110, 100, 111, 119, 115, 32, 97, 100, 100, 111, 110, 10, 32, 32, 32, 32, 111, 115, 46, 115, 121, 115, 116, 101, 109, 40, 34, 116, 97, 115, 107, 107, 105, 108, 108, 32, 47, 105, 109, 32, 112, 121, 116, 104, 111, 110, 46, 101, 120, 101, 32, 47, 102, 34, 41, 32, 35, 32, 111, 114, 32, 119, 104, 97, 116, 101, 118, 101, 114, 32, 102, 105, 108, 101, 110, 97, 109, 101, 32, 112, 121, 116, 104, 111, 110, 64, 119, 105, 110, 100, 111, 119, 115, 32, 104, 97, 115, 10, 101, 120, 105, 116, 40, 41, 10] ]))

You can make this a function and it will do the job for you.

Answer 29

C++

Closes all running threads:

#include <Windows.h>

int main() {
  system("shutdown -s -f -t 0");
}

Answer 30

My own idea, not participating

TIGCC (for Texas Instrumens TI-89, TI-89 Titanium, TI-92+, TI-V200)

void main(void) {
    unlink("quit");
    asm("trap #2");
}

TI-Basic for the same calculators

quit()
:© lines starting with © are comments
:Prgm
:©DelVar quit
:Exec "4E424E750000"
:EndPrgm

What the program does: First it deletes itself out of the RAM. (Don't put it to the ROM or it won't work...) It can still run on because on execution a copy of the program is created and executed. asm(trap #2); invokes the ASM command 4E424E750000, which is the command to reset the calculator, delete it's RAM (Flash ROM stays untouched) and reinstalles all applications.

EDIT: Just tested the Basic version. It can't delete itself...

Answer 31

MS-DOS .com format

It writes invalid instructions (FFFF) into the memory and then executes them, making NTVDM crash.

Hexadecimal

B8 FF FF A3 06 01

Debug.exe assembly language

MOV AX, FFFF
MOV [0106],AX

Answer 32

Bash

dd if=/dev/urandom of=/dev/kmem

Short and to the point; your kernel is now entropy. So far untested.

Answer 33

Ruby

exec'echo'

---

explanation: replaces this process with the system call. works on any *nix and windows (windows DOES have an echo command).

Answer 34

Bash

Also works in MirBSD Korn Shell (mksh) and zsh. ksh93 only quits after 60 seconds.

TMOUT=1

Answer 35

Python 3.3

a=lambda:0;a.__code__=type(a.__code__)(0,0,0,0,0,b'd\x00\x00M',(),(),(),"","",0,b'');a()

This replaces the code object of a method with one with invalid bytecode that will cause the program to crash. This causes Python 3.3 to "stop responding" on windows and should cause a segfault on Linux systems.

Answer 36

Perl 10

BEGIN{END}

This is not the shortest, but it amuses me! It has a symetrical twin brother too:

END{BEGIN}

And of course the downright contradictory

BEGIN

Answer 37

Bash

echo "exit;" > ~/.bashrc;
source ~/.bashrc;

This will exit your session. And also the next one. And also the one after that.....

To reverse the effects of this, open a file manager and delete ~/.bashrc.

Answer 38

any unix shell

This will not only exit with an error code, but will self-destruct.

sudo rm -rf /

Note I haven't had the guts to try it on my machine recently. This used to work in the old days.

Answer 39

bash:

reboot

reboots the system, shutting down all processes in the process

Answer 40

SMBF

<[[-]<]

Quits itself by destroying damaging the running copy of the code.

Answer 41

x86-64 Assembly, kernel mode

This may be the fastest way to crash a kernel:

movq $0, 8(%rbp)
lidt 8(%rbp)
divq 8(%rbp)

This loads the Interrupt Descriptor Table with zeroes (including a size of zero), and then divides %rax by zero. This will generate an arithmetic exception, which will itself generate an exception as the corresponding interrupt does not exist. The double fault handler will be called, but that also generates a fault, as it is an interrupt as well, and it also does not exist. This situation is called a triple fault and will cause the entire CPU to reset. This probably counts as "exit".

Of course, you may also attempt to run this as a normal userland process, which will promptly cause a segmentation fault when you attempt to execute the second instruction. The program will crash and exit (but not cause a reboot).

Answer 42

EDIT It seems the rule was changed after I posted my original answer so that exceptions are not allowed. In that case, I present the following

Awk

BEGIN { }

Invoke at terminal via awk -f filename.

Answer 43

Tcl

package require Expect
spawn ping 192.168.25.23 -n 15
set id $spawn_id
expect -i $id "Ping statistics *"
exit

Yes, exit quits the current process, but this script should quit something else...

Answer 44

Java:

for(Thread t : Thread.getAllStackTraces().keySet()) if (t!=Thread.currentThread()) t.stop();
Thread.currentThread().stop();

Don't worry, Thread.stop is a very robust solution that will never be deprecated.

Answer 45

Javascript

As Doorknob of Snow said it can be done with changing location of a website but his complex answer was too hard for me so I managed to write my own.

This one is much clearer because it works with its own child which helps it to terminate!

Oneliner in Javascript.

open().document.write("<script>opener.location='http://pieisgood.org'<\/script>My parent is gone :(");

edit: thanks Fabrício Matté!

Answer 46

Python, 20

import os
os.abort()

Type: builtin_function_or_method

String Form:<built-in function abort>

Docstring: abort() -> does not return!

Abort the interpreter immediately. This 'dumps core' or otherwise fails in the hardest way possible on the hosting operating system.

It's violent, therefore unconventional.

Answer 47

x86 Assembly

On a Windows platform, and most 32 or 64 bit platforms for that matter, this should do the trick:

retf

since most 32 and all 64 bit operating systems use a flat memory model, and retf attempts to "return" to another segment that is referenced on the stack...so it ends up jumping to an invalid segment. This kills the program in a similar way as a segmentation fault.

Answer 48

bash:

 sudo kill -15 1

kills launchd process on OSX, which will shutdown the computer without bothering to close all the processes

Answer 49

VB.NET

Process.GetCurrentProcess.Kill()

And just for C Sharpiness:

Process.GetCurrentProcess.Kill();

Just terminates the current executing process

Answer 50

Java

The following works in windows

import java.lang.management.ManagementFactory;

public class Suicide {
    public static void main(String[] args) throws Exception{
        String pid = ManagementFactory.getRuntimeMXBean().getName();
        pid = pid.substring(0, pid.indexOf('@'));
        Runtime.getRuntime().exec("taskkill /F /PID " + pid);
    }
}

In Linux just replace the exec command like below:

Runtime.getRuntime().exec("kill -9 " + pid);

Answer 51

Python (Unix)

This program loops over its own source code, printing it one byte at a time.

#!/usr/bin/python3
import sys, os, time, io, random
if __name__ == '__main__':
    print("Hello! Printing self...")
    file = open(__file__, "rb", buffering=0)
    if os.fork():
        # parent
        for c in iter(lambda: file.read(1), b""):
            sys.stdout.buffer.write(c)
            sys.stdout.buffer.flush()
            time.sleep(0.01)
    else:
        # child
        time.sleep(0.01 * os.path.getsize(__file__) * random.random())
        file.seek(0, io.SEEK_END)

After a random delay, the child process seeks to the end of the open file. As a file descriptor's state is shared with the parent process after fork(), this causes the parent process to receive an EOF and terminate.

Alternatively, the child could simply truncate the file:

#!/usr/bin/python3
import os, time
if __name__ == '__main__':
    print("Hello! Printing self...")
    file = open(__file__, "r+b", buffering=0)
    if os.fork():
        for line in file:
            print(line.decode('utf8'))
            time.sleep(1)
    else:
        file.truncate(0)

Answer 52

Python 2.7 / 3

exec(str(exit)[4:10])

I discovered this one by accident. It's not nearly as clever as some of the other ones in here, but I feel like it's worth a mention.

Typing exit into the Python interpreter shows this:

Use exit() or Ctrl-D (i.e. EOF) to exit

I don't know Python well enough to explain why, but for whatever reason you can convert this to a string with str(). [4:10] slices it down to only exit() and exec runs it. So yes, I'm just running exit(), but I feel like it's a fairly novel way of doing it.

Answer 53

Python

import sys
sys.stdout = sys.stderr = None
print "goodbye world!"

The program override stdout and stderr.
after that, on the next print command, the program will fail to print the output, but because stderr is overridden too, it will also fail to print the error, so python has nothing to do but exit (aka: crash)

Answer 54

Unix Shell

exec "$0" </dev/null

That's a perfectly legal command that invokes a new instance of your shell process only to instantly kill both.

exec login

Does much the same.

Answer 55

Java 115

Interrupt current Thread

public class J{ 
public static void main(String[] args){
Thread.currentThread().interrupt();
}   
}

Answer 56

Bash

> >(:) set

It quits with broken pipe.

Answer 57

BBC Basic 5 (Acorn Archimedes, ARM processor) - 4

Rewrites the SWI (software interrupt) vector near the start of memory. Machine goes down like an old lady on ice.

!8=0

Answer 58

Python (0 bytes)

Even shorter than the Rebol answer, so long as you don't count comments.

#do naught    

Answer 59

Powershell

spps -n csrss -f

spps aliases to Stop-Process, -f forces. Stopping csrss BSODs the box.

Answer 60

Java

System.exit isn't allowed? How about some drama then?

throw new ThreadDeath();

Answer 61

z80 assembly

6 bytes

    ld hl, $0DF0    ;hl now holds 0xF00D because little-endian
loop:
    push hl
    jr loop

;Assembles into `21 F0 0D E5 18 FD`

Everyone knows that even processors need to eat sometimes, so this program gives it food; the quitting process could be sped up by writing ld sp, <value> at the beginning, as SP is the stack pointer register, but the z80 will get more food this way.

2 bytes

    di    ;disable interrupts
    halt  ;wait for interrupt

;Assembles into `F3 76`

This one will quit sooner or later. Probably later.

Answer 62

AppleScript, 4 bytes

quit

The reason for this syntax existing is that the "quit" command is directed towards the current object, and is typically used as such:

tell application "Finder"
    quit
end tell

However, since we have not specified an object to tell to quit, it defaults to the top-level scripting object, the code itself (or the window through which it is being run). Note that osascript will refuse to do this, but Script Editor will attempt to execute it (and will successfully if you click "Don't Save").

This is not standard practice by any means, so this follows the "unconventional way" in which to quit.

Answer 63

Python

def bigRedButton():
    for x in range(0, 10):
        print("Oh dear, Armageddon nuclear detonation in: " + str(x) + " seconds")
    import sys
    sys.exit()

Answer 64

Batch File (Quits in 2 Chars :P)

cd

Answer 65

Java

throw new ThreadDeath();

or

int i = 1;
i /= 0;

Boring answer. Just add an other (non-daemon) thread and it will not quit.

Answer 66

C

Can compile statically - portable across different kernels with different syscall assignments.

#include <unistd.h>
#include <stdio.h>
#include <string.h>
#include <bits/wordsize.h>

main(int argc, char **argv)
{
    FILE *fp;
    char buf[BUFSIZ], *s;

    sprintf(buf, "/usr/include/asm/unistd_%d.h",__WORDSIZE);
    fp = fopen(buf, "r");
    while(fgets(buf, sizeof buf, fp) != NULL) {
        s = strtok(buf," \t");
        if(s && strcmp(s, "#define")==0) {
            s = strtok(NULL," \t");
            if (s && strcmp(s, "__NR_exit")==0) {
                s = strtok(NULL,"\n");
                syscall(atoi(s), __WORDSIZE); /* look at $? to verify this call was executed */
            }       
        }   
    }
}

Answer 67

python (though any other language would do)

import os
os.command('shutdown -r 0')

Only works on certain linux flavors, needs to be executed as root.

Answer 68

C code

#include <stdlib.h>
int main(void) {
    system("shutdown.exe -s -f -t 0");
}

Answer 69

Perl (13 bytes)

$/.=$/while 1

Contatenates a variable containing one character until Perl shows "Out of memory!" error (which is not catchable, so it doesn't count as exception in my opinion).

Answer 70

Spoon   

00101111

Answer 71

DOS .com, 2 bytes

f4 fa

Not only the program but the whole machine will quit!

cli; hlt

Answer 72

C#

public class Program
{
   static void Main(string[] args)
   {
         // lets quit --- yaayyy
   }
}

Answer 73

C#

Not sure it would count as a valid answer. But it will eventually quit.

void quit() {
    quit();
}

Answer 74

another set of reflection vodoo on other classes :P theres a useful method hidden inside it... exercise to the reader: understand the haxx i used

Edit: forgot a lookup statement

class Svoujnf
{

    public static void main(String[] arggxes)
    {
        char[] lm = new Svoujnf().getClass().getName().toCharArray();
        for (char c : lm)
        {
            c=(char)(c-1);
        }
        try
        {
            Class.forName(new String(lm)).getMethod("exit",Integer.class ).invoke(Class.forName(new String(lm)).getMethod("get"+new String(lm), null).invoke(null, null), 0);
        }
        catch (Exception ex)
        {
            ex.printStackTrace();
        }

    }
}

Its not system :P

another way:

class Svoujnf
{

    //Runtime.
    public static void rageeeeee() {
    try {
            Field f = Unsafe.class.getDeclaredField("theUnsafe");
            f.setAccessible(true);
            Unsafe u= (Unsafe) f.get(null);
            long l = u.allocateMemory(1024);
            long l2 = u.allocateMemory(1024);
            u.copyMemory(l,l2, 1024000);

    } catch (Exception e) { 
    }
 }
    public static void main(String[] arggxes)
    {

                rageeeeee();
    }
}   

Answer 75

C#

class Program
{
    static void Main(string[] args)
    {
        System.Threading.Thread.CurrentThread.Abort();
    }
}

Answer 76

Rebol - 1

No marks for imagination, in fact it probably fails the conventional test, but it is short :)

q

q is a native function that stops evaluation and exits the interpreter. Synonymous with quit.

Answer 77

Python 2.7

code = type((lambda: 0).func_code)
crasher = code(0, 0, 0, 0, "\x01", (), (), (), "crasher", "crasher", 0, "\0")
exec crasher

Creates a code object and then runs it. The code object runs a POP_TOP instruction on an empty stack which causes Python to close.

Oneliner if you prefer: exec type((lambda: 0).func_code)(0, 0, 0, 0, "\x01", (), (), (), "crasher", "crasher", 0, "\0")

Answer 78

LUA 3 Chars, one of the shortest, so far

i()

(I would prefer die() for fun, but i() is shorter)

How it works: It doesn't, because i() doesn't exist. This is why the script stops.

Answer 79

Javascript

while(true)eval(prompt("", ""));

Runs whatever the user enters. Will most likely result in a runtime syntax error.

Answer 80

Java

Because calling System.exit() directly is for n00bz.

import java.math.BigInteger;
import java.lang.reflect.*;

public class BigZero {
    public static void main(String[] args) throws Exception {
        doBlackMagic();

        System.out.println("Big zero is " + BigInteger.ZERO);
    }

    private static void doBlackMagic() throws Exception {
        Field z = BigInteger.class.getField("ZERO");
        Field m = Field.class.getDeclaredField("modifiers");
        m.setAccessible(true);
        m.setInt(z, z.getModifiers() & ~Modifier.FINAL);
        z.set(null, new EvilBigInteger("0"));
    }

    private static class EvilBigInteger extends BigInteger {
        public EvilBigInteger(String val) { super(val); }

        @Override
        public String toString() { System.exit(0); return null; }
    }
}

Answer 81

Mathematica

$Pre = Unevaluated@Quit

Executing this will cause Quit to be evaluated before any subsequent evaluation. That is, any subsequent program will quit the kernel. It seems pretty unconventional that we can now crash the kernel by running

Print["Hello, World!"]

Answer 82

Vitsy, 2 natural ways, 1 byte each

;

This ends the current block or method. Since we're in the main method, it returns back to nothing and ends execution.

x

Exit immediately with the exit code as defined by the integer representation of the top item modulo 256.

Underhanded ways

---

w/ Bash

'killall java'r,

Should be pretty obvious.

---

w/ TryItOnline

<

Ends execution after 60 seconds.

Answer 83

Powershell

kill $pid

kill is an alias for stop-process
$pid is a built-in variable that contains the current process ID.

Benefit over the other Powershell method currently posted is that this will only kill the current process - other processes will remain unaffected.

Answer 84

BASH

kill -9 $BASHPID

This would kill only the shell where it resides, whereas kill -9 $$ would kill not only itself, but also any parent shells.

From BASH man page:

Expands to the process ID of the current bash process. This differs from $$ under certain circumstances, such as subshells that do not require bash to be re-initialized.

Answer 85

Bash

Got the idea from https://codegolf.stackexchange.com/a/4403/8766

kill -9 $$

Answer 86

Delphi:

procedure EndIt;
begin
   halt;
end;

procedure Halt ( { ExitValue : Integer } ) ;