A "cheating" quine

Question

Long-time lurker, first-time poster. So here goes.

In the Wikipedia page for quine, it says that "a quine is considered to be 'cheating' if it looks at its own source code." Your task is to make one of these "cheating quines" that reads its own source code.

This is code-golf, so the shortest code in bytes - in each language - wins. This means that a 5-byte Pyth script would not beat a 21-byte Python script - but a 15-byte Python script would.

You must use file I/O to read the source code, so the following JavaScript code, taken from the official Wikipedia page, is invalid:

function a() {
    document.write(a, "a()");
}
a()

It must access the source code of the file on disk.

You are not allowed to specify the file name. You must make it detect the filename itself.

Everyone clear? Go!

Answer 1

F#, 54 Bytes

printf"%s"(System.IO.File.ReadAllText __SOURCE_FILE__)

Usage:

fsi --exec a.fsx

Answer 2

Perl 5, 15 13 bytes

Credit to the Bash solution for inspiring this:

print`cat $0`

EDIT: Don't need the semi-colon or first space.

Answer 3

Scala(2.10), 101 bytes

import scala.reflect.io.File;object A extends App{print(File(getClass.getName.head+".scala").slurp)}

Similar to the Java and C# answers. The only "interesting" parts here are the .head to drop the $ from the class name and the slurp method (which I'd never seen before) to read the file in as a String.

Answer 4

Python 2, 27 bytes

print next(open(__file__))

Python 3, 28 bytes

print(next(open(__file__)))

Byte count includes new line.

Answer 5

Raku, 17 bytes

$?LANG.orig.print

Try it online!

This relies on some compiler internals.

Answer 6

Java - 214 194

import java.io.*;class Q{Q(){try{System.out.print(new BufferedReader(new FileReader(getClass().getName()+".java")).readLine());}catch(Exception e){}}public static void main(String[]a){new Q();}}

Reduced a lot with using @VoteToClose method of finding the filename for java.

Readable version:

import java.io.*;

class Q {
        Q() {
                try {
                        System.out.print(new BufferedReader(new FileReader(getClass().getName()+".java")).readLine());
                } catch(Exception e) {}
        }
        public static void main(String[] a) {
                new Q();
        }
}

NOTE: The readable version doesn't actually work, it just reads the first line. Just to show what the code is doing

Answer 7

JavaScript (node.js), 65

with(process)require('fs').createReadStream(argv[1]).pipe(stdout)

Answer 8

C#, 153 bytes

class A{static void Main(){new A();}A([System.Runtime.CompilerServices.CallerFilePath]string s=""){System.Console.Write(System.IO.File.ReadAllText(s));}}

Readable version:

class A
{
    static void Main()
    {
        new A();
    }

    A([System.Runtime.CompilerServices.CallerFilePath] string s = "")
    {
        System.Console.Write(System.IO.File.ReadAllText(s));
    }
}

Thanks to @Johnbot for the idea to use CallerFilePathAttribute, which avoids any kind of name hardcoding!

Answer 9

Perl, 9 bytes

#!/bin/dd

Perl allows you to change the parser while the file's being read. One thing you can do is to change the program that parses the file entirely via the use of #! on the first line; this feature was intended to allow the use of Perl to fix a system on which shebangs didn't work correctly. dd with no parameters copies standard input to standard output (followed by some statistics on standard error which shouldn't matter), thus is a suitable program to use for a cheating-quine (because Perl reloads the file from disk to give to dd.)

Answer 10

Python 3, 28 35 32 29 21 bytes

lambda:open(__file__)

Try it online! File objects are iterable, and output in a singleton iterable is allowed.

lambda:open(__file__)  # full program
lambda:                # define function taking no arguments which returns...
       open(        )  # file at path...
            __file__   # current script path

Answer 11

Javascript (Babel Node), 74 72 bytes

Thanks to Kyle Slattery for posting his answer about __filename.

Also, thanks to Makonede for saving 2 bytes and making my answer correct.

require('fs').readFile(__filename,'utf8',(e,d)=>process.stdout.write(d))

Answer 12

Python, 22 bytes

input(*open(__file__))

Attempt This Online!

Answer 13

Shell + xargs, 27 bytes

xargs -0a/proc/self/cmdline

Attempt This Online!

On Linux, the file /proc/self/cmdline contains the arguments provided to the current command, including the command's name itself, separated by null bytes. In this case, the command is xargs, and the argument is -0a/proc/self/cmdline.

xargs -0 splits its input on null bytes, and passes them to another command. When a second command isn't specified, it defaults to echo. The -a option makes xargs read from a file instead of STDIN.

I'm not 100% sure if this is valid, because strictly speaking the source code of the shell script itself isn't in /proc/self/cmdline, but it certainly isn't a proper quine, so I think it morally ought to be allowed.

Answer 14

*nix interpreter directive, 10 bytes

#!/bin/cat

Shebang (#!) abuse. The shebang causes the "code" to be "interpreted" using cat, which prints out the content of the file.

EDIT: Someone else came up with it before me.

Answer 15

JavaScript (Node.js), 56 bytes

with(require('fs'))writeSync(1,readFileSync(__filename))

Try it online!

Answer 16

VBScript, 67 bytes

CreateObject("WScript.Shell").Run "cmd /K type "&Wscript.ScriptName

Answer 17

C (Win32), 36 bytes

main(){CopyFileA(__FILE__,"CON",0);}

CopyFile makes the challenge easier in Win32 than in POSIX or ISO C, that's for sure. You however need to call the compiler with stdcall as its default calling convention.

Answer 18

Aubergine, 22 bytes, noncompeting

The tab character at the end signals end of file, and the interpreters all crash without it. It's cool that this challenge showed up on my radar this week since I just finished golfing this for the wiki.

-a1+a1=oA=Bi-BA:bB=ia   

I'll explain how it works later. It does not use file I/O but it very much does read its listing, and it is definitely cheating.

Answer 19

Groovy 92 bytes

Shorter than the other groovy answer, in addition to being filename agnostic.

print new Error().stackTrace*.fileName.collect{it?new File(it):null}.find{it?.exists()}.text

No newline at end of file.

Answer 20

Vitsy, 4 bytes

This language feature is newer than this question, but not made for this question.

iG`Z

i     Grab input. Since there is no input, it pushes -1 to the stack.
 G    Get the class name of the referenced class. -1 refers to the current class.
  `   Read the file under the name of the stack's contents and push all of it to the stack.
   Z  Output everything in the stack.

As of November 24, class commands allow for referencing other programs accessible by disk, or 'classes'. Normally, it'd be used something like this:

00k

;u someothervitsyfile

Where I execute the 0th line (the first line) of the 0th index of the uses list ('someothervitsyfile'). I can get its name with G like so:

0GZ

;u someothervitsyfile

And, if I have the name, I can get its contents like so:

0G`Z

;u someothervitsyfile

But the special cases of this are -2 and -1, where -2 references the superclass (as defined by ;e) and -1 references the current class.

So, to get the name of the current class, I use -1, get its name, and, with its name being the only thing in the stack, I pull its contents with `.

Very fancy.

You cannot try this online, as it has been disabled to prevent reading server files.

Answer 21

Mouse-2002, 8 bytes

Expects to be put in a file called MOUSE.001. (Files with the names MOUSE.nnn are the only files Mouse knows how to perform I/O on. I didn't write the interpreter.)

If the EOF char at the end of the file, which is printed to the terminal, crashes your terminal, it's not my fault and I consider this a feature, not a bug.

(1 &F!')

Additionally, technically this is undefined behaviour (though most of Mouse is undefined except in practice) because it promises that the file's length is at least as long as the while(true). If this hangs your system because it's a loop, save your work, run git commit && git push, and don't say I didn't warn you.

Answer 22

Lua, 31 Bytes

print(io.open(arg[1]):read'*a')

The Arg table contains the following in lua.

{Filename, Command Line Argument1, Command Line Argument 2, ...}

Answer 23

SmileBASIC, 69 68 bytes

LOAD"PRG1:"+PRGNAME$(0),FALSE
PRGEDIT 1
FOR I=0 TO 3?PRGGET$();
NEXT

Load the program into slot 0 (the default slot), and run!

Explanation

LOAD"PRG1:"+PRGNAME$(0),FALSE  load the source code into program slot 1
PRGEDIT 1                      open program slot 1 for editing
FOR I=0 TO 3                   loop 3 times { (no newline here)
?PRGGET$();                      print line, supressing extra newline
NEXT                           }

The ,FALSE on LOAD is required to supress a confirmation dialogue. I wasn't sure if this was required so I threw it in anyways (seems like it should be).

The extra setup of loading the source code into the neighbouring slot is required as SmileBASIC can't read or write from the currently loaded source code for some reason (it clearly reads it to load it into the other slot, but whatever).

As the output format isn't specified, you might be able to get away with just using the first line and claiming the output is found on slot one (which is one tap away) for 29 bytes.

Answer 24

SmileBASIC, 26 bytes (newline at end)

Saw @redstarcoder 's answer and wanted to out-golf it. I'm not sorry.

?LOAD("TXT:"+PRGNAME$());

This exploits the fact that PRG is just a resource subtype of TXT (it's literally the same file format with a different icon) and loads the source file into a string. It's then simply printed.

I removed unneeded whitespace wherever the parser would let me, and put it all on one line for show. ? is just a shorthand for PRINT. The ; at the end ensures the PRINT doesn't add an extra newline. This one also doesn't disable the load dialog popup, but whatever.

If you remove the newline using a program that deletes the last character (since SB automatically adds a LF whenever you save through the editor) you can also remove the semicolon, bringing the answer down to 24 bytes. I didn't do this though, because I consider it kinda underhanded.

Answer 25

Node.js, 63 bytes

Uses the __filename global to obtain its file path as opposed to process.argv[1], which can be flawed:

require('fs').createReadStream(__filename).pipe(process.stdout)

Answer 26

GW-BASIC / Applesoft BASIC / IBM BASIC / Commodore BASIC,  6 bytes

1 LIST

Pretty simple. No matter where you loaded the program from or how much is in it, it will always print everything in the program buffer, including itself.

Answer 27

R, 44 bytes

cat(scan(sub(".*=","",commandArgs()[4]),""))

Prints to stderr as well. If that's not allowed this works for 46 bytes:

cat(readLines(sub(".*=","",commandArgs()[4])))

Run these from the command line using Rscript.

Answer 28

Burlesque - 25 bytes

With-IO

,%____FILE?rfQ

Disclaimer: I've just added ____FILE because I/O support is still very rudimentary and there was no way of detecting the name of the file. Otherwise this would have been impossible. I/O built-ins aren't available in default builds but can be activated by using ghc ... -DHAVE_IO_UNSAFE ....

Without-IO:

,#Q2 SH ~- ",#Q" \/ .+ sh

Explanation: Burlesque is nasty.

Actual explanation: #Q looks at its own source code and pushes the code that is left in the "execution pipeline" onto the stack. In otherwords: #Q pushes all the code that is to the right to the stack. However, #Q does not look at ALL the source code just what is left in the "execution pipeline of the current execution context":

blsq ) 2ro{#Qj}m[
{1 {j} 2 {j}}

The #Q here is only able to see the j due to the execution context.

On a side-note: Burlesque has other modifiers that allow you to modify code such as for example #q which allows you to overwrite the remaining code in the execution pipeline of the current execution context:

blsq ) 3 4 {?*}#q?+
12

{?*}#q overwrites the ?+ with ?*. With #J we can inject/delay a piece of code by appending it to the execution pipeline:

blsq ) 3 4 {J?*}#J?+
49

The #J here appends J?* to the ?+.

Answer 29

Racket, 63 bytes

#lang racket
(display(file->string(find-system-path'run-file)))

Try it online!

Pretty straightforward - just finds the current file, reads it, and prints it back out.

Answer 30

Knight (C/AST, *nix), 50 49 bytes

\t represents a raw tab.

O`"cat `tr '\0' '\t'</proc/$PPID/cmdline|cut -f3`"

Doesn't work in the golfed interpreter for some reason, so no TIO.

Abuses the shell command built-in <backtick> and the standardized command line args for Knight, which is knight -f file.kn

/proc/$PPID/cmdline obtains the \0-separated command line arguments of the parent process (which is the knight interpreter itself), tr '\0' '\t' replaces \0 with \t, and cut -f3 takes the third tab-delimited argument. Then, we just cat the file and output the result.

A similar result can be done using the -e flag, but that doesn't read the source file from the disk (unless you count the cmdline file)

-1 byte using a raw tab over \t