Copy stdin to stdout

From Rosetta Code
Task
Copy stdin to stdout
You are encouraged to solve this task according to the task description, using any language you may know.

Create an executable file that copies stdin to stdout, or else a script that does so through the invocation of an interpreter at the command line.

8086 Assembly 

READ:	equ	3Fh		; MS-DOS syscalls
WRITE:	equ	40h
BUFSZ:	equ	4000h		; Buffer size
	cpu	8086
	bits	16
	org	100h
section	.text
read:	mov	ah,READ		; Read into buffer
	xor	bx,bx		; From STDIN (file 0)
	mov	cx,BUFSZ
	mov	dx,buffer
	int	21h
	test	ax,ax		; Did we read anything?
	jz	done		; If not, stop
	xchg	ax,cx		; Write as many bytes as read
	mov	ah,WRITE
	inc	bx		; To STDOUT (file 1)
	int	21h
	jmp	read		; Go get more
done:	ret	
section	.bss
buffer:	resb	BUFSZ

Action! 

PROC Main()
  CHAR c

  DO 
    c=GetD(7)
    Put(c)
  UNTIL c=27 ;repeat until Esc key is pressed
  OD
RETURN
Output:

Screenshot from Atari 8-bit computer 

COPY STDIN TO STDOUT

Ada 

with Ada.Text_IO;

procedure Copy_Stdin_To_Stdout is
   use Ada.Text_IO;
   C : Character;
begin
   while not End_Of_File loop
      Get_Immediate (C);
      Put (C);
   end loop;
end Copy_Stdin_To_Stdout;

Aime 

file f;
data b;
f.stdin;
while (f.b_line(b) ^ -1) {
    o_(b, "\n");
}

ALGOL 68

Works with: ALGOL 68G version Any - tested with release 2.8.3.win32
BEGIN
    BOOL at eof := FALSE;
    # set the EOF handler for stand in to a procedure that sets "at eof" to true #
    # and returns true so processing can continue                                #                               
    on logical file end( stand in, ( REF FILE f )BOOL: at eof := TRUE );
    # copy stand in to stand out                                                 #
    WHILE STRING line; read( ( line, newline ) ); NOT at eof DO write( ( line, newline ) ) OD
END

Applesoft BASIC 

0 GET C$ : PRINT C$; : GOTO

AWK

Using the awk interpreter, the following command uses the pattern // (which matches anything) with the default action (which is to print the current line) and so copy lines from stdin to stdut. 

awk "//"

BCPL 

get "libhdr"

let start() be
$(  let c = rdch()
    if c = endstreamch then finish
    wrch(c)
$) repeat

Brainf*** 

,[.,]

Binary Lambda Calculus

As explained on https://www.ioccc.org/2012/tromp/hint.html, `cat' is the 4-bit program 

0010

in bit-wise BLC, or any one of the 16 characters in the ASCII range from space to slash 

 !"#$%&'()*+,-./

in byte-wise BLC.

C 

#include <stdio.h>

int main() {
  int c;
  while ((c = getchar()) != EOF) {
    putchar(c);
  }
  return 0;
}

C#

Works with: .NET Framework version 4.0 or later
using System;

class Program
{
    static void Main(string[] args)
    {
        Console.OpenStandardInput().CopyTo(Console.OpenStandardOutput());
    }
}

C++ 

#include <iostream>
#include <iterator>

int main() {
    using namespace std;
    noskipws(cin);
    copy(
        istream_iterator<char>(cin),
        istream_iterator<char>(),
        ostream_iterator<char>(cout)
    );
    return 0;
}

Shorter and quicker alternative: 

#include <iostream>

int main() {
    std::cout << std::cin.rdbuf();
}

CLU 

start_up = proc ()
    pi: stream := stream$primary_input()
    po: stream := stream$primary_output()
    
    while true do
         stream$putc(po, stream$getc(pi))
    end except when end_of_file:
         return
    end
end start_up

Commodore BASIC

Commodore BASIC assigns device #0 (keyboard) as the standard input device, and device #3 (screen) as the standard output device. By opening channels for input and/or output, data can be sent to/from files, printers, and other peripheral devices. Although the keyboard and screen are the default input and output devices, they can be read from and written to using the same conventions as other devices, which is useful if a program wants to allow a user to direct output elsewhere (e.g. printing a hard copy of a report instead of displaying it on the screen)

Commodore Device Addresses
Number Device
0 Keyboard
1 Datassette Tape Drive
2 User Port (RS-232)
3 Text Screen
4 IEC Bus Printers
5
6 IEC Bus Plotters
7
8-30 Floppy/Hard Disk Drives

The following program opens channels to devices chosen by the user, then uses the GET# and PRINT# I/O statements instead of the standard GET and PRINT (for typical keyboard/screen interaction.) When keyboard and/or screen are chosen, BASIC ignores the extra filename and file type parameters normally used for other devices. Peripheral devices (tape, disk drive) use STATUS register to flag end of file, however the keyboard does not. When using the keyboard, the program terminates on a CTRL-Z. 

10 print chr$(147);chr$(14);
11 print "0:Keyboard  1:Tape  2:RS-232  3:Screen"
12 print "4-7:printers/plotters"
13 print "8-11:Disk Drives":print
14 input "Input device";d1
15 if d1=1 or d1>=8 then input "Filename for INPUT";i$
16 input "Output device";d2
17 if d2=1 or d2>=8 then input "Filename for OUTPUT";o$
18 print:if d1=0 then print "Begin typing. Press CTRL-Z to end.":print
20 open 5,d1,5,"0:"+i$+",s,r"
30 open 2,d2,2,"@0:"+o$+",s,w"
40 get#5,a$
50 if (d1=0 and a$=chr$(26)) or (d1>0 and st>0) then close 5:close 2:end
60 print#2,a$;
70 goto 40
Output:

The output sample below demonstrates the following device input-output combinations:

  • Keyboard (0) to Screen (3)
  • Keyboard (0) to Disk File (8)
  • Disk File (8) to Screen (3)


0:Keyboard  1:Tape  2:RS-232  3:Screen  
4-7:printers/plotters                   
8-11:Disk Drives                        
                                        
Input device? 0                         
Output device? 3                        
                                        
Begin typing. Press CTRL-Z to end.      
                                        
Hello. This is so much fun on Rosetta Code!                                     
                                        
Goodbye!                                
                                        
ready.   
run

0:Keyboard  1:Tape  2:RS-232  3:Screen  
4-7:printers/plotters                   
8-11:Disk Drives                        
                                        
Input device? 0                         
Output device? 8                        
Filename for OUTPUT? rosetta.txt        
                                        
Begin typing. Press CTRL-Z to end.      

[No echo of text because output is directed to file.]
                                        
ready.                                  
run

0:Keyboard  1:Tape  2:RS-232  3:Screen  
4-7:printers/plotters                   
8-11:Disk Drives                        
                                        
Input device? 8                         
Filename for INPUT? rosetta.txt         
Output device? 3                        
                                        
These device numbers are unique to the Commodore line of 8-bit computers.       
                                        
ready.                   
█

Common Lisp 

#|Loops while reading and collecting characters from STDIN until EOF (C-Z or C-D)
Then concatenates the characters into a string|#
(format t
  (concatenate 'string 
    (loop for x = (read-char *query-io*) until (or (char= x #\Sub) (char= x #\Eot)) collecting x)))

Crystal 

STDIN.each_line do |line|
  puts line
end

D 

import std.stdio;

void main() {
    foreach (line; stdin.byLine) {
        writeln(line);
    }
}

Dart 

import 'dart:io';

void main() {
  var line = stdin.readLineSync();
  stdout.write(line);
}

Delphi

→ See Pascal

Draco 

\util.g

proc nonrec main() void:
    char c;
    while
        /* I/O is line-oriented, so first read characters
         * from the current line while that is possible */
        while read(c) do write(c) od;
        case ioerror()
            /* Then once it fails, if the line is empty,
             * try to go to the next line. */
            incase CH_MISSING:
                readln();
                writeln();
                true
            /* If it failed for another reason (which will be
             * EOF here), stop. */
            default:
                false
        esac
    do od
corp

F# 

let copy()=let n,g=stdin,stdout
           let rec fN()=match n.ReadLine() with "EOF"->g.Write "" |i->g.WriteLine i; fN()
           fN()
copy()

Factor 

USING: io kernel ;

[ read1 dup ] [ write1 ] while drop

Forth

Works with: gforth version 0.7.3
stdin slurp-fid type bye

FreeBASIC 

#define FIN 255  'eof is already a reserved word
#include "crt/stdio.bi"  'provides the C functions getchar and putchar
dim as ubyte char
do
    char = getchar()
    if char = FIN then exit do else putchar(char)
loop

Frink

The special string "-" indicates reading from stdin. 

print[read["-"]]

FutureBasic

This code uses FileHandles to interact with standard input and standard output. It continuously reads from standard input and writes to standard output until it reaches the end of input. 

// Create file handles for standard input and output
FileHandleRef  stdIn = fn FileHandleWithStandardInput
FileHandleRef stdOut = fn FileHandleWithStandardOutput

// Continuously read from standard input…
while (YES)
  CFDataRef availableData = fn FileHandleAvailableData( stdIn )
  if ( fn DataLength( availableData ) == 0 )
    break  // End of input
  end if
  // … and write to standard output
  fn FileHandleWriteData( stdOut, availableData, NULL )
wend

Go 

package main

import (
    "bufio"
    "io"
    "os"
)

func main() {
    r := bufio.NewReader(os.Stdin)
    w := bufio.NewWriter(os.Stdout)
    for {
        b, err := r.ReadByte()       
        if err == io.EOF {
            return
        }
        w.WriteByte(b)
        w.Flush()
    }   
}

io.Copy

package main

import (
	"io"
	"os"
)

func main() {
	io.Copy(os.Stdout, os.Stdin)
}

Groovy 

class StdInToStdOut {
    static void main(args) {
        try (def reader = System.in.newReader()) {
            def line
            while ((line = reader.readLine()) != null) {
                println line
            }
        }
    }
}

Haskell 

main = interact id

Java

Copies until no more input. 

import java.util.Scanner;

public class CopyStdinToStdout {

    public static void main(String[] args) {
        try (Scanner scanner = new Scanner(System.in);) {
            String s;
            while ( (s = scanner.nextLine()).compareTo("") != 0 ) {
                System.out.println(s);
            }
        }
    }

}

Alternative, concise version (Java 9+): 

public class CopyStdinToStdout {
    public static void main(String[] args) throws java.io.IOException {
        System.in.transferTo(System.out);
    }
}
Output:

Output interleaved. Stdin and Stdout are same window. 

Line 1.
Line 1.
Line 2.
Line 2.

JavaScript

JavaScript in the browser does not have a stdin or stdout, but using Node.js we have: 

process.stdin.resume();
process.stdin.pipe(process.stdout);

node index.js < index.js
Output:
process.stdin.resume();
process.stdin.pipe(process.stdout);

jq 

jq -Rr .

Julia 

while !eof(stdin)
    write(stdout, read(stdin, UInt8))
end

Kotlin 

fun main() {
    var c: Int
    do {
        c = System.`in`.read()
        System.out.write(c)
    } while (c >= 0)
}

Latitude 

while { $stdin eof? not. } do {
  $stdout putln: $stdin readln.
}.

Lua 

lua -e 'for x in io.lines() do print(x) end'

Mercury 

:- module stdin_to_stdout.
:- interface.

:- import_module io.

:- pred main(io::di, io::uo) is det.

%-----------------------------------------------------------------------------%
%-----------------------------------------------------------------------------%

:- implementation.

:- import_module char.
:- import_module list.
:- import_module string.

%-----------------------------------------------------------------------------%



main(!IO) :-
    io.read_line_as_string(Result, !IO),
    (
        Result = ok(Line),
        io.write_string(Line, !IO),
        main(!IO)
    ;
        Result = eof
    ;
        Result = error(Error),
        io.error_message(Error, Message),
        io.input_stream_name(StreamName, !IO),
        io.progname("stdin_to_stdout", ProgName, !IO),
        io.write_strings([
            ProgName, ": ",
            "error reading from `", StreamName, "': \n\t",
            Message, "\n"
        ], !IO)
    ).

%-----------------------------------------------------------------------------%

Nim 

stdout.write readAll(stdin)

OCaml 

try
  while true do
    output_char stdout (input_char stdin)
  done
with End_of_file -> ()

Ol 

(bytestream->port (port->bytestream stdin) stdout)

Pascal 

program writeInput(input, output);
var
	buffer: char;
begin
	while not EOF() do
	begin
		read(buffer); // shorthand for read(input, buffer)
		write(buffer); // shorthand for write(output, buffer)
	end;
end.

PascalABC.NET

See C# 

##
Console.OpenStandardInput().CopyTo(Console.OpenStandardOutput());


Perl 

perl -pe ''

Phix 

without js
while true do
    integer ch = wait_key()
    if ch=#1B then exit end if
    puts(1,ch)
end while

PicoLisp 

(in NIL (echo))

Prolog 

%File: stdin_to_stdout.pl
:- initialization(main).

main :- repeat,
	get_char(X),
	put_char(X),
	X == end_of_file,
	fail.

Invocation at the command line (with Swi-prolog): 

swipl stdin_to_stdout.pl

Python 

python -c 'import sys; sys.stdout.write(sys.stdin.read())'

R 

Rscript -e 'cat(readLines(file("stdin")))'

Racket 

#lang racket

(let loop ()
  (match (read-char)
    [(? eof-object?) (void)]
    [c (display c)
       (loop)]))

Raku

(formerly Perl 6) When invoked at a command line: Slightly less magical than Perl / sed. The p flag means automatically print each line of output to STDOUT. The e flag means execute what follows inside quotes. ".lines" reads lines from the assigned pipe (file handle), STDIN by default. 

raku -pe'.lines'

When invoked from a file: Lines are auto-chomped, so need to re-add newlines (hence .say rather than .print) 

.say for lines

Refal 

$ENTRY Go {
    , <Card>: {
        0 = ;
        e.Line = <Go <Prout e.Line>>;
    };
};

REXX

In the REXX language,   the   STDIN   (default input stream)   is normally the console,   and the   STDOUT   (default output stream)   is normally the console.   So for REXX, this task equates to copying data from the console to itself. 

/*REXX pgm copies data from STDIN──►STDOUT (default input stream──►default output stream*/

  do while chars()\==0                           /*repeat loop until no more characters.*/
  call charin  , x                               /*read  a char from the  input stream. */
  call charout , x                               /*write "   "    "   "   output   "    */
  end   /*while*/                                /*stick a fork in it,  we're all done. */

Ring 

? "give input: " give str
? "output: " + str
Output:
give input:
Ring Programming Language
output: Ring Programming Language

Ruby 

$stdout << $stdin.gets

Rust 

use std::io;

fn main() {
    io::copy(&mut io::stdin().lock(), &mut io::stdout().lock());
}

Scala

For Scala 2's compiler scalac, a containing object is required: 

object CopyStdinToStdout extends App {
  io.Source.fromInputStream(System.in).getLines().foreach(println)
}

If it's being run directly by scala, it can be shortened to one line, and run directly in the shell: 

scala -e "io.Source.fromInputStream(System.in).getLines().foreach(println)"

Scheme 

(do ((c (read-char) (read-char)))
    ((eof-object? c) 'done)
  (display c))

sed 

sed -e ''

Seed7 

$ include "seed7_05.s7i";
  include "fileutil.s7i";

const proc: main is func
  begin
    copyFile(IN, OUT);
  end func;

Smalltalk

Works with: Smalltalk/X
"using Stream class's bulk copy method:"
Stdin copyToEndInto:Stdout.

"line wise"
[Stdin atEnd] whileFalse:[ Stdout nextPutLine:(Stdin nextLine) ].

"character wise"
[Stdin atEnd] whileFalse:[ Stdout nextPut:(Stdin next) ].

"no EOF test, but handle EOF Exception"
[
    [ Stdout nextPut:(Stdin next) ] loop.
] on: StreamError do:[]

Standard ML 

fun copyLoop () =
  case TextIO.input TextIO.stdIn of
    "" => ()
  | tx => copyLoop (TextIO.output (TextIO.stdOut, tx))

val () = copyLoop ()

Symsyn 

Loop [] []
     go Loop

Tcl 

package require Tcl 8.5

chan copy stdin stdout
# fcopy stdin stdout for older versions

VBScript

VBScript can't get single chars from stdin, so we have to implement it line to line. Ctrl-Z+Enter stops. 

do
  s=wscript.stdin.readline
  wscript.stdout.writeline s 
loop until asc(left(s,1))=26

Wren

In the following script, stdin and stdout are both assumed to be connected to a terminal.

Bytes are read from stdin and written to stdout until the return key is pressed. 

import "io" for Stdin, Stdout

Stdin.isRaw = true // prevents echoing to the terminal
while (true) {
    var byte = Stdin.readByte()         // read a byte from stdin
    if (byte == 13) break               // break when enter key pressed
    System.write(String.fromByte(byte)) // write the byte (in string form) to stdout
    Stdout.flush()                      // flush output
}
System.print()
Stdin.isRaw = false

XPL0

Device 1 is stdin without echoing a character to the screen. Device 0 (or 1) is stdout, which displays the character on the monitor. This program can list a file to the screen like this: stdio <file.txt 

int C;
loop    [C:= ChIn(1);
        if C = $1A \EOF\ then quit;
        ChOut(0, C);
        ]

zkl 

zkl --eval "File.stdout.write(File.stdin.read())"
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