Execute a system command

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Task
Execute a system command
You are encouraged to solve this task according to the task description, using any language you may know.
Task

Run either the   ls   system command   (dir   on Windows),   or the   pause   system command.

Related task



11l[edit]

os:(‘pause’)

ABAP[edit]

ABAP report which checks if there is an external command called 'ls' for the os of the current application server. When running on Windows, it calls dir, for all other platforms ls. A new command is created if not existing and run.

*&---------------------------------------------------------------------*
*& Report  ZEXEC_SYS_CMD
*&
*&---------------------------------------------------------------------*
*&
*&
*&---------------------------------------------------------------------*

REPORT  zexec_sys_cmd.

DATA: lv_opsys      TYPE          syst-opsys,
      lt_sxpgcotabe TYPE TABLE OF sxpgcotabe,
      ls_sxpgcotabe LIKE LINE OF  lt_sxpgcotabe,
      ls_sxpgcolist TYPE          sxpgcolist,
      lv_name       TYPE          sxpgcotabe-name,
      lv_opcommand  TYPE          sxpgcotabe-opcommand,
      lv_index      TYPE          c,
      lt_btcxpm     TYPE TABLE OF btcxpm,
      ls_btcxpm     LIKE LINE OF  lt_btcxpm
      .

* Initialize
lv_opsys = sy-opsys.
CLEAR lt_sxpgcotabe[].

IF lv_opsys EQ 'Windows NT'.
  lv_opcommand = 'dir'.
ELSE.
  lv_opcommand = 'ls'.
ENDIF.

* Check commands
SELECT * FROM sxpgcotabe INTO TABLE lt_sxpgcotabe
  WHERE opsystem  EQ lv_opsys
    AND opcommand EQ lv_opcommand.

IF lt_sxpgcotabe IS INITIAL.
  CLEAR ls_sxpgcolist.
  CLEAR lv_name.
  WHILE lv_name IS INITIAL.
* Don't mess with other users' commands
    lv_index = sy-index.
    CONCATENATE 'ZLS' lv_index INTO lv_name.
    SELECT * FROM sxpgcostab INTO ls_sxpgcotabe
      WHERE name EQ lv_name.
    ENDSELECT.
    IF sy-subrc = 0.
      CLEAR lv_name.
    ENDIF.
  ENDWHILE.
  ls_sxpgcolist-name      = lv_name.
  ls_sxpgcolist-opsystem  = lv_opsys.
  ls_sxpgcolist-opcommand = lv_opcommand.
* Create own ls command when nothing is declared
  CALL FUNCTION 'SXPG_COMMAND_INSERT'
    EXPORTING
      command                = ls_sxpgcolist
      public                 = 'X'
    EXCEPTIONS
      command_already_exists = 1
      no_permission          = 2
      parameters_wrong       = 3
      foreign_lock           = 4
      system_failure         = 5
      OTHERS                 = 6.
  IF sy-subrc <> 0.
* Implement suitable error handling here
  ELSE.
* Hooray it worked! Let's try to call it
    CALL FUNCTION 'SXPG_COMMAND_EXECUTE_LONG'
      EXPORTING
        commandname                   = lv_name
      TABLES
        exec_protocol                 = lt_btcxpm
      EXCEPTIONS
        no_permission                 = 1
        command_not_found             = 2
        parameters_too_long           = 3
        security_risk                 = 4
        wrong_check_call_interface    = 5
        program_start_error           = 6
        program_termination_error     = 7
        x_error                       = 8
        parameter_expected            = 9
        too_many_parameters           = 10
        illegal_command               = 11
        wrong_asynchronous_parameters = 12
        cant_enq_tbtco_entry          = 13
        jobcount_generation_error     = 14
        OTHERS                        = 15.
    IF sy-subrc <> 0.
* Implement suitable error handling here
      WRITE: 'Cant execute ls - '.
      CASE sy-subrc.
        WHEN 1.
          WRITE: / ' no permission!'.
        WHEN 2.
          WRITE: / ' command could not be created!'.
        WHEN 3.
          WRITE: / ' parameter list too long!'.
        WHEN 4.
          WRITE: / ' security risk!'.
        WHEN 5.
          WRITE: / ' wrong call of SXPG_COMMAND_EXECUTE_LONG!'.
        WHEN 6.
          WRITE: / ' command cant be started!'.
        WHEN 7.
          WRITE: / ' program terminated!'.
        WHEN 8.
          WRITE: / ' x_error!'.
        WHEN 9.
          WRITE: / ' parameter missing!'.
        WHEN 10.
          WRITE: / ' too many parameters!'.
        WHEN 11.
          WRITE: / ' illegal command!'.
        WHEN 12.
          WRITE: / ' wrong asynchronous parameters!'.
        WHEN 13.
          WRITE: / ' cant enqueue job!'.
        WHEN 14.
          WRITE: / ' cant create job!'.
        WHEN 15.
          WRITE: / ' unknown error!'.
        WHEN OTHERS.
          WRITE: / ' unknown error!'.
      ENDCASE.
    ELSE.
      LOOP AT lt_btcxpm INTO ls_btcxpm.
        WRITE: / ls_btcxpm.
      ENDLOOP.
    ENDIF.
  ENDIF.
ENDIF.

Ada[edit]

Using the IEEE POSIX Ada standard, P1003.5c:

with POSIX.Unsafe_Process_Primitives;

procedure Execute_A_System_Command is
   Arguments : POSIX.POSIX_String_List;
begin
   POSIX.Append (Arguments, "ls");
   POSIX.Unsafe_Process_Primitives.Exec_Search ("ls", Arguments);
end Execute_A_System_Command;

Importing the C system() function:

with Interfaces.C; use Interfaces.C;

procedure Execute_System is
    function Sys (Arg : Char_Array) return Integer;
    pragma Import(C, Sys, "system");
    Ret_Val : Integer;
begin
    Ret_Val := Sys(To_C("ls"));
end Execute_System;

Using the GNAT run-time library:

with Ada.Text_IO;     use Ada.Text_IO;
with System.OS_Lib;   use System.OS_Lib;
 
procedure Execute_Synchronously is
   Result    : Integer;
   Arguments : Argument_List :=
                 (  1=> new String'("cmd.exe"),
                    2=> new String'("/C dir c:\temp\*.adb")
                 );
begin
   Spawn
   (  Program_Name           => "cmd.exe",
      Args                   => Arguments,
      Output_File_Descriptor => Standout,
      Return_Code            => Result
   );
   for Index in Arguments'Range loop
      Free (Arguments (Index)); -- Free the argument list
   end loop;
end Execute_Synchronously;

Aikido[edit]

The simplest way to do this is using the system() function. It returns a vector of strings (the output from the command).

var lines = system ("ls")
foreach line lines {
    println (line)
}

If you don't want to process the output you can use the exec function. It writes the output to the standard output stream by default;

exec ("ls")

You also have the regular fork and execv calls available:

var pid = fork()
if (pid == 0) {
    var args = ["/bin/ls"]
    execv ("/bin/ls", args)
    exit(1)
}
var status = 0
waitpid (pid, status)

Aime[edit]

sshell ss;

ss.argv.insert("ls");

o_(ss.link);

ALGOL 68[edit]

Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9 - "system" is not part of the standard's prelude.
system("ls")

Or the classic "!" shell escape can be implemented as an "!" operator:

Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9 - "system" & "ANDF" are not part of the standard's prelude.
OP ! = (STRING cmd)BOOL: system(cmd) = 0;

IF ! "touch test.tmp" ANDF ( ! "ls test.tmp" ANDF ! "rm test.tmp" ) THEN
  print (("test.tmp now gone!", new line))
FI


Amazing Hopper[edit]

#!/usr/bin/hopper

#include <hopper.h>

main:

  /* execute "ls -lstar" with no result return (only displayed) */
  {"ls -lstar"},execv
    
  /* this form does not allow composition of the line with variables.
     Save result in the variable "s", and then display it */
  s=`ls -l | awk '{if($2=="2")print $0;}'`
  {"\n",s,"\n"}print
  
  data="2"
  {""}tok sep

  // the same as above, only I can compose the line:
  {"ls -l | awk '{if($2==\"",data,"\")print $0;}'"}join(s),{s}exec,print
  {"\n\n"}print
  
  // this does the same as above, with an "execute" macro inside a "let" macro:
  t=0,let (t := execute( {"ls -l | awk '{if($2==\""},{data},{"\")print $0;}'"} ))
  {t,"\n"}print

{0}return

APL[edit]

 system s;handle
  ⍝⍝ NOTE: one MUST give the full absolute path to the program (eg. /bin/ls)
  ⍝⍝   Exercise: Can you improve this by parsing the value of
  ⍝⍝    ⎕ENV 'PATH' ?
  ⍝⍝
  handle  ⎕fio['fork_daemon'] s                 
  ⎕fio['fclose'] handle

      system '/bin/ls /var'
      backups  games     lib    lock  mail  run    tmp
cache    gemini  local  log   opt   spool

AppleScript[edit]

do shell script "ls" without altering line endings

Applesoft BASIC[edit]

? CHR$(4)"CATALOG"

Arturo[edit]

print execute "ls"

AutoHotkey[edit]

Run, %comspec% /k dir & pause

AutoIt[edit]

Run(@ComSpec & " /c " & 'pause', "", @SW_HIDE)

AWK[edit]

Using system() function:

BEGIN {
  system("ls")		# Unix
 #system("dir")		# DOS/MS-Windows
}

Using getline command:

BEGIN {
         ls = sys2var("ls")
         print ls
}
function sys2var(command        ,fish, scale, ship) {
         command = command " 2>/dev/null"
         while ( (command | getline fish) > 0 ) {
             if ( ++scale == 1 )
                 ship = fish
             else
                 ship = ship "\n" fish
         }
         close(command)
         return ship
}

BASIC[edit]

SHELL "dir"

BaCon[edit]

' Execute a system command
SYSTEM "ls"

BASIC256[edit]

system "dir"

Batch File[edit]

dir

BBC BASIC[edit]

On Acorn computers the *CAT command catalogues the current directory, the equivalent of the Unix ls command or the DOS/Windows dir command. The BBC BASIC OSCLI command passes a string to the Command Line Interpreter to execute a system command, it is the equivalent of C's system() command.

OSCLI "CAT"

With BBC BASIC for Windows you can execute the Windows dir command:

OSCLI "*dir":REM *dir to bypass BB4W's built-in dir command

And if running BBC BASIC on a Unix host, you can execute the ls command:

OSCLI "ls"

Befunge[edit]

Works with: Befunge version 98

Works with any Funge-98 on Unix, try https://tio.run/##S0pNK81LT9W1tNAtqAQz//9XKs5RsnX4/x8A

"sl"=@;pushes ls, = executes it, @ ends it;


BQN[edit]

•SH is a function defined in the BQN spec, which provides output from a shell command.

The arguments to •SH are the command, followed by its arguments as a flat list of strings. For example:

•SH ⟨"ls"⟩

Will give an output as a list of three elements: the command's exit code, text written to stdout, and text written to stderr.

Bracmat[edit]

sys$dir

Brat[edit]

include :subprocess 

p subprocess.run :ls  #Lists files in directory

Brlcad[edit]

exec ls

C[edit]

ISO C & POSIX:

#include <stdlib.h>

int main()
{
    system("ls");
    return 0;
}

C#[edit]

Using Windows / .NET:

using System.Diagnostics;

namespace Execute
{
    class Program
    {
        static void Main(string[] args)
        {
            Process.Start("cmd.exe", "/c dir");
        }
    }
}
Works with: MCS version 1.2.3.1
using System;
 
  class Execute {
     static void Main() {
         System.Diagnostics.Process proc = new System.Diagnostics.Process();
         proc.EnableRaisingEvents=false;
         proc.StartInfo.FileName="ls";
         proc.Start();
    }
 }

C++[edit]

Works with: Visual C++ version 2005
system("pause");

Clojure[edit]

(.. Runtime getRuntime (exec "cmd /C dir"))
user=> (use '[clojure.java.shell :only [sh]])

user=> (sh "ls" "-aul")

{:exit 0, 
 :out total 64
drwxr-xr-x  11 zkim  staff    374 Jul  5 13:21 .
drwxr-xr-x  25 zkim  staff    850 Jul  5 13:02 ..
drwxr-xr-x  12 zkim  staff    408 Jul  5 13:02 .git
-rw-r--r--   1 zkim  staff     13 Jul  5 13:02 .gitignore
-rw-r--r--   1 zkim  staff  12638 Jul  5 13:02 LICENSE.html
-rw-r--r--   1 zkim  staff   4092 Jul  5 13:02 README.md
drwxr-xr-x   2 zkim  staff     68 Jul  5 13:15 classes
drwxr-xr-x   5 zkim  staff    170 Jul  5 13:15 lib
-rw-r--r--@  1 zkim  staff   3396 Jul  5 13:03 pom.xml
-rw-r--r--@  1 zkim  staff    367 Jul  5 13:15 project.clj
drwxr-xr-x   4 zkim  staff    136 Jul  5 13:15 src
, :err }
user=> (use '[clojure.java.shell :only [sh]])

user=> (println (:out (sh "cowsay" "Printing a command-line output")))

 _________________________________ 
< Printing a command-line output. >
 --------------------------------- 
        \   ^__^
         \  (oo)\_______
            (__)\       )\/\
                ||----w |
                ||     ||

nil

CMake[edit]

Works with: Unix
execute_process(COMMAND ls)

Because of a quirk in the implementation (cmExecuteProcessCommand.cxx and ProcessUNIX.c), CMake diverts the standard output to a pipe. The effect is like running ls | cat in the shell. The ls process inherits the original standard input and standard error, but receives a new pipe for standard output. CMake then reads this pipe and copies all data to the original standard output.

execute_process() can also chain commands in a pipeeline, and capture output.

# Calculate pi to 40 digits after the decimal point.
execute_process(
  COMMAND printf "scale = 45; 4 * a(1) + 5 / 10 ^ 41\\n"
  COMMAND bc -l
  COMMAND sed -e "s/.\\{5\\}$//"
  OUTPUT_VARIABLE pi OUTPUT_STRIP_TRAILING_WHITESPACE)
message(STATUS "pi is ${pi}")
-- pi is 3.1415926535897932384626433832795028841972

COBOL[edit]

Works with: OpenCOBOL
CALL "SYSTEM" USING BY CONTENT "ls"

CoffeeScript[edit]

Works with: Node.js
{ spawn } = require 'child_process'

ls = spawn 'ls'

ls.stdout.on 'data', ( data ) -> console.log "Output: #{ data }"

ls.stderr.on 'data', ( data ) -> console.error "Error: #{ data }"

ls.on 'close', -> console.log "'ls' has finished executing."

Common Lisp[edit]

Works with: CMUCL
(with-output-to-string (stream) (extensions:run-program "ls" nil :output stream))
Works with: LispWorks
(system:call-system "ls")
Library: trivial-shell
(trivial-shell:shell-command "ls")
Library: uiop
; uiop is part of the de facto build system, asdf, so should be available to most installations.

; synchronous
(uiop:run-program "ls")

; async
(defparameter *process* (uiop:launch-program "ls"))
(uiop:wait-process *process*)

D[edit]

import std.process, std.stdio;
//these two alternatives wait for the process to return, and capture the output
//each process function returns a Tuple of (int)"status" and (string)"output
auto ls_string = executeShell("ls -l"); //takes single string
writeln((ls_string.status == 0) ? ls_string.output : "command failed");

auto ls_array = execute(["ls", "-l"]); //takes array of strings
writeln((ls_array.status == 0) ? ls_array.output : "command failed");
//other alternatives exist to spawn processes in parallel and capture output via pipes

std.process.system() is deprecated.

dc[edit]

! ls


DBL[edit]

XCALL SPAWN ("ls *.jpg > file.txt")     ;execute command and continue
XCALL EXEC ("script.sh")                ;execute script or binary and exit    
STOP '@/bin/ls *.jpg > file.txt'        ;exit and execute command

DCL[edit]

Directory
Or, shorter
dir

Delphi[edit]

program ExecuteSystemCommand;

{$APPTYPE CONSOLE}

uses Windows, ShellApi;

begin
  ShellExecute(0, nil, 'cmd.exe', ' /c dir', nil, SW_HIDE);
end.

E[edit]

def ls := makeCommand("ls")
ls("-l")

def [results, _, _] := ls.exec(["-l"])
when (results) -> {
  def [exitCode, out, err] := results
  print(out)
} catch problem {
  print(`failed to execute ls: $problem`)
}

Emacs Lisp[edit]

Synchronously (shell, interactive):

(shell-command "ls")

Asynchronously (shell, interactive):

(async-shell-command "ls")

Erlang[edit]

os:cmd("ls").

ERRE[edit]

In ERRE language you have the SHELL command followed, eventually, by a string command. SHELL itself opens a new DOS/Windows shell: you must use EXIT to end. For example

 SHELL("DIR/W")

lists the current directory and then returns to the program.

cmd$="DIR/W"
SHELL(cmd$)

Euphoria[edit]

Euphoria has 2 systems command functions: system() and system_exec().

 -- system --
-- the simplest way --
-- system spawns a new shell so I/O redirection is possible --

system( "dir /w c:\temp\ " ) -- Microsoft --

system( "/bin/ls -l /tmp" ) -- Linux BSD OSX --

----

 -- system_exec() --                                                                                                                                         
 -- system_exec does not spawn a new shell --                                                                                                                  
 -- ( like bash or cmd.exe ) --                                                                                                                                 

integer exit_code = 0
sequence ls_command = ""

ifdef UNIX or LINUX or OSX then
    ls_command = "/bin/ls -l "
elsifdef WINDOWS then
    ls_command = "dir /w "
end ifdef

exit_code = system_exec( ls_command )

if exit_code = -1 then
    puts( STDERR, " could not execute " & ls_command & "\n" )
elsif exit_code = 0 then
    puts( STDERR, ls_command & " succeeded\n")
else
    printf( STDERR, "command %s failed with code %d\n", ls_command, exit_code)
end if

F#[edit]

System.Diagnostics.Process.Start("cmd", "/c dir")

Factor[edit]

"ls" run-process wait-for-process

Fantom[edit]

The Process class handles creating and running external processes. in/out/err streams can be redirected, but default to the usual stdin/stdout/stderr. So following program prints result of 'ls' to the command line:

class Main
{
  public static Void main ()
  {
    p := Process (["ls"])
    p.run
  }
}

Forth[edit]

Works with: gforth version 0.6.2
s" ls" system

Fortran[edit]

execute_command_line subroutine in Fortran 2008 and later runs a system command

program SystemTest
integer :: i
 call execute_command_line ("ls", exitstat=i)
end program SystemTest
Works with: gfortran

The SYSTEM subroutine (and function) are a GNU extension.

program SystemTest
  call system("ls")
end program SystemTest

FreeBASIC[edit]

' FB 1.05.0 Win64

Shell "dir"
Sleep

Frink[edit]

r = callJava["java.lang.Runtime", "getRuntime"]
println[read[r.exec["dir"].getInputStream[]]]

FunL[edit]

import sys.execute

execute( if $os.startsWith('Windows') then 'dir' else 'ls' )

FutureBasic[edit]

This simple example prints the output to a console window. With its open "Unix" command, FB has robust capability as a system interface to the Free BSD Unix core of Macintosh OS X 10.x.

include "ConsoleWindow"

local fn DoUnixCommand( cmd as str255 )
  dim as str255 s

  open "Unix", 2, cmd
  while ( not eof(2) )
    line input #2, s
    print s
  wend
  close 2
end fn

fn DoUnixCommand( "ls -A" )

Output:

.DocumentRevisions-V100
.Spotlight-V100
.Trashes
.file
.fseventsd
.hotfiles.btree
.vol
Applications
Library
Network
System
Users
Volumes
bin
cores
dev
etc
home
mach_kernel
net
private
sbin
tmp
usr
var

Gambas[edit]

Click this link to run this code

Public Sub Main()

Shell "ls -aul"

End

Output:

total 36364
drwxr-xr-x  88 charlie charlie     4096 May 29 10:26 .
drwxr-xr-x   5 root    root        4096 May 26 15:44 ..
drwxr-xr-x   2 charlie charlie     4096 May 29 10:54 15PuzzleGame
drwx------   3 charlie charlie     4096 May 28 13:51 .adobe
drwxr-xr-x   4 charlie charlie     4096 May 28 13:52 .audacity-data
drwxr-xr-x   4 charlie charlie     4096 May 28 13:51 .barcode
etc....

Genie[edit]

[indent=4]
/*
  Execute system command, in Genie

  valac executeSystemCommand.gs
  ./executeSystemCommand
*/

init
    try
        // Non Blocking
        Process.spawn_command_line_async("ls")
    except e : SpawnError
        stderr.printf("%s\n", e.message)
Output:

Output is asynchronous (could be made synchronous with spawn_command_line_sync), and elided here for the sample capture.

prompt$ valac executeSystemCommand.gs
prompt$ ./executeSystemCommand
...
aplusb            executeSystemCommand       hello.gs          helloNoNewline.gs
memavail          progress-bar               readfile.vapi     stringsample.vala
...

gnuplot[edit]

!ls

Go[edit]

package main

import (
    "log"
    "os"
    "os/exec"
)

func main() {
    cmd := exec.Command("ls", "-l")
    cmd.Stdout = os.Stdout
    cmd.Stderr = os.Stderr
    if err := cmd.Run(); err != nil {
        log.Fatal(err)
    }
}

Groovy[edit]

println "ls -la".execute().text

GUISS[edit]

Start,Programs,Accessories,MSDOS Prompt,Type:dir[enter]

Haskell[edit]

Works with: GHCi version 6.6
import System.Cmd

main = system "ls"

See also: the System.Process module

HicEst[edit]

SYSTEM(CoMmand='pause')
SYSTEM(CoMmand='dir & pause')

HolyC[edit]

HolyC is the official programming language for The Temple Operating System (TempleOS). The Temple Operating System interpreter executes just-in-time compiled HolyC code. All HolyC code is effectively executed as system commands.

For example, to execute the Dir command:

Dir;

Icon and Unicon[edit]

The code below selects the 'ls' or 'dir' command at runtime based on the UNIX feature.

procedure main()

write("Trying command ",cmd := if &features == "UNIX" then "ls" else "dir")
system(cmd)

end

Unicon extends system to allow specification of files and a wait/nowait parameter as in the examples below.

  pid := system(command_string,&input,&output,&errout,"wait") 
  pid := system(command_string,&input,&output,&errout,"nowait")

IDL[edit]

$ls

Will execute "ls" with output to the screen.

spawn,"ls",result

will execute it and store the result in the string array "result".

spawn,"ls",unit=unit

will execute it asynchronously and direct any output from it into the LUN "unit" from whence it can be read at any (later) time.

Io[edit]

System runCommand("ls") stdout println

IS-BASIC[edit]

100 EXT "dir"

J[edit]

The system command interface in J is provided by the standard "task" script:

load'task'

NB.  Execute a command and wait for it to complete
shell 'dir'

NB.  Execute a command but don't wait for it to complete 
fork 'notepad'

NB.  Execute a command and capture its stdout
stdout   =:  shell 'dir'  

NB.  Execute a command, provide it with stdin, 
NB.  and capture its stdout
stdin    =:  'blahblahblah'
stdout   =:  stdin spawn 'grep blah'

Note that on unix systems, you can also use the 2!:x family of foreign verbs to execute system commands.

Java[edit]

Works with: Java version 1.5+
import java.util.Scanner;
import java.io.*;

public class Program {
    public static void main(String[] args) {    	
    	try {
    		Process p = Runtime.getRuntime().exec("cmd /C dir");//Windows command, use "ls -oa" for UNIX
    		Scanner sc = new Scanner(p.getInputStream());    		
    		while (sc.hasNext()) System.out.println(sc.nextLine());
    	}
    	catch (IOException e) {
    		System.out.println(e.getMessage());
    	}
    }
}
Works with: Java version 1.4+

There are two ways to run system commands. The simple way, which will hang the JVM (I would be interested in some kind of reason). -- this happens because the the inputStream buffer fills up and blocks until it gets read. Moving your .waitFor after reading the InputStream would fix your issue (as long as your error stream doesn't fill up)

import java.io.IOException;
import java.io.InputStream;

public class MainEntry {
    public static void main(String[] args) {
        executeCmd("ls -oa");
    }

    private static void executeCmd(String string) {
        InputStream pipedOut = null;
        try {
            Process aProcess = Runtime.getRuntime().exec(string);
            aProcess.waitFor();

            pipedOut = aProcess.getInputStream();
            byte buffer[] = new byte[2048];
            int read = pipedOut.read(buffer);
            // Replace following code with your intends processing tools
            while(read >= 0) {
                System.out.write(buffer, 0, read);
                
                read = pipedOut.read(buffer);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException ie) {
            ie.printStackTrace();
        } finally {
            if(pipedOut != null) {
                try {
                    pipedOut.close();
                } catch (IOException e) {
                }
            }
        }
    }
    
    
}

And the right way, which uses threading to read the InputStream given by the process.

import java.io.IOException;
import java.io.InputStream;

public class MainEntry {
    public static void main(String[] args) {
        // the command to execute
        executeCmd("ls -oa");
    }

    private static void executeCmd(String string) {
        InputStream pipedOut = null;
        try {
            Process aProcess = Runtime.getRuntime().exec(string);

            // These two thread shall stop by themself when the process end
            Thread pipeThread = new Thread(new StreamGobber(aProcess.getInputStream()));
            Thread errorThread = new Thread(new StreamGobber(aProcess.getErrorStream()));
            
            pipeThread.start();
            errorThread.start();
            
            aProcess.waitFor();
        } catch (IOException e) {
            e.printStackTrace();
        } catch (InterruptedException ie) {
            ie.printStackTrace();
        }
    }
}

//Replace the following thread with your intends reader
class StreamGobber implements Runnable {

    private InputStream Pipe;

    public StreamGobber(InputStream pipe) {
        if(pipe == null) {
            throw new NullPointerException("bad pipe");
        }
        Pipe = pipe;
    }

    public void run() {
        try {
            byte buffer[] = new byte[2048];

            int read = Pipe.read(buffer);
            while(read >= 0) {
                System.out.write(buffer, 0, read);

                read = Pipe.read(buffer);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if(Pipe != null) {
                try {
                    Pipe.close();
                } catch (IOException e) {
                }
            }
        }
    }
}

JavaScript[edit]

JavaScript does not have any facilities to interact with the OS. However, host environments can provide this ability.

Works with: JScript
var shell = new ActiveXObject("WScript.Shell");
shell.run("cmd /c dir & pause");
Works with: Rhino
runCommand("cmd", "/c", "dir", "d:\\");
print("===");
var options = {
    // can specify arguments here in the options object
    args: ["/c", "dir", "d:\\"],
    // capture stdout to the options.output property
    output: ''
};
runCommand("cmd", options);
print(options.output);

Joy[edit]

<
"ls" system.

Julia[edit]

The Julia manual has an excellent section on this topic, which is worth a read. The short answer on Linux is:

run(`ls`)
Output:
$ ls
bitmap_bresenham_line.jl   completed                  single_link_list_collection.jl
color_quantization_in.png  execute_system_command.jl  single_link_list_insert.jl
color_quantization.jl      README.md                  support
$ julia execute_system_command.jl
bitmap_bresenham_line.jl   completed                  single_link_list_collection.jl
color_quantization_in.png  execute_system_command.jl  single_link_list_insert.jl
color_quantization.jl      README.md                  support

K[edit]

Execute "ls"

    \ls

Execute "ls" and capture the output in the variable "r":

   r: 4:"ls"

Kotlin[edit]

// version 1.0.6

import java.util.Scanner

fun main(args: Array<String>) {
    val proc = Runtime.getRuntime().exec("cmd /C dir")  // testing on Windows 10
    Scanner(proc.inputStream).use {
        while (it.hasNextLine()) println(it.nextLine())
    }
}

Lang5[edit]

For one-word commands:

'ls system

For multi-word commands:

"ls -a" system

Lasso[edit]

local(
	path	= file_forceroot,
	ls	= sys_process('/bin/ls', (:'-l', #path)),
	lswait	= #ls -> wait
)
'<pre>'
#ls -> read
'</pre>'
total 16
drwxr-xr-x  8 _lasso  staff  272 Nov 10 08:13 mydir
-rw-r--r--  1 _lasso  staff   38 Oct 29 16:05 myfile.lasso
-rw-r--r--@ 1 _lasso  staff  175 Oct 29 18:18 rosetta.lasso

LFE[edit]

In the LFE REPL:

> (os:cmd "ls -alrt")

That will display output on a single line, with literal newlines.

For pretty output, compose with io:format:

> (io:format (os:cmd "ls -alrt"))

Liberty BASIC[edit]

 drive1$ = left$(Drives$,1)
run "cmd.exe /";drive1$;" dir & pause"

Limbo[edit]

There is no equivalent to Unix's exec() in Inferno per se; commands are just modules that have at least an init() function with the correct signature, and are loaded the same way as any other module. (As a result, there's nothing in the language or OS that prevents a program from acting as both a command and a library except convention.)

This version passes its argument list through to ls:

implement Runls;

include "sys.m"; sys: Sys;
include "draw.m";
include "sh.m";

Runls: module {
	init: fn(ctxt: ref Draw->Context, args: list of string);
};

init(ctxt: ref Draw->Context, args: list of string)
{
	sys = load Sys Sys->PATH;
	ls := load Command "/dis/ls.dis";
	if(ls == nil)
		die("Couldn't load /dis/ls.dis");
	ls->init(ctxt, "ls" :: tl args);
}

die(s: string)
{
	sys->fprint(sys->fildes(2), "runls: %s: %r", s);
	raise "fail:errors";
}

It's not strictly necessary to pass the graphics context to ls, but it is generally a good idea to do so when calling another program.

Lingo[edit]

Library: Shell Xtra
sx = xtra("Shell").new()
if the platform contains "win" then
  put sx.shell_cmd("dir")
else
  put sx.shell_cmd("ls")
end if

Locomotive Basic[edit]

The Amstrad CPC464 uses a ROM based basic interpreter, so every statement within the program is a system command. If a command without a line number is typed, whilst the computer is in a ready state, the command gets executed immediately. There is no pause command, so in this example, we use the list command (which exhibits totally different behaviour to a pause command):

LIST

[edit]

Works with: UCB Logo

The lines of output of the SHELL command are returned as a list.

print first butfirst shell [ls -a]   ; ..

Logtalk[edit]

Using the standard library:

os::shell('ls -a').

Lua[edit]

-- just executing the command
os.execute("ls")

-- to execute and capture the output, use io.popen
local f = io.popen("ls") -- store the output in a "file"
print( f:read("*a") )    -- print out the "file"'s content

M2000 Interpreter[edit]

Locale 1033  // for the chr$(string) : converτ ANSI to UTF16LE
Dos "chdir "+quote$(dir$)+"&&  dir /w > out.txt";
Wait 100
Print "Press Space or Mouse to see next page"
A$=chr$(eval$(buffer("out.txt")))
Report a$  // view text using proportional typing, and at pages, with 3/4height scroll


M4[edit]

syscmd(ifdef(`__windows__',`dir',`ls'))

Make[edit]

make can use system command in either definition of variables or in the targets

in definition

contents=$(shell cat foo)
curdir=`pwd`

in target

mytarget:
   cat foo | grep mytext

Maple[edit]

ssystem("dir");

Mathematica / Wolfram Language[edit]

Run["ls"]

MATLAB[edit]

To execute system commands in MATLAB, use the "system" keyword.

Sample Usage:

>> system('PAUSE')

Press any key to continue . . . 
 

ans =

     0

Maxima[edit]

system("dir > list.txt")$

MAXScript[edit]

dosCommand "pause"

Mercury[edit]

:- module execute_sys_cmd.
:- interface.
:- import_module io.

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

:- implementation.

main(!IO) :-
   io.call_system("ls", _Result, !IO).

min[edit]

Works with: min version 0.19.3
!dir

Modula-2[edit]

MODULE tri;

FROM   SYSTEM           IMPORT  ADR;
FROM   SysLib           IMPORT  system;

IMPORT TextIO, InOut, ASCII;

VAR   fd                : TextIO.File;
      ch                : CHAR;

PROCEDURE SystemCommand (VAR  command : ARRAY OF CHAR) : BOOLEAN;

BEGIN
   IF  system (ADR (command) ) = 0  THEN
      RETURN TRUE
   ELSE
      RETURN FALSE
   END
END SystemCommand;

BEGIN
   IF  SystemCommand ("ls -1 tri.mod | ") = TRUE  THEN
      InOut.WriteString ("No error reported.")
   ELSE
      InOut.WriteString ("Error reported!")
   END;
   LOOP
      InOut.Read (ch);
      InOut.Write (ch);
      IF  ch < ' '  THEN  EXIT  END
   END;
   InOut.WriteLn;
   InOut.WriteBf
END tri.

Modula-3[edit]

This code requires the UNSAFE keyword because M3toC deals with C strings (which are pointers), and are implemented in Modula-3 as UNTRACED, meaning they are not garbage collected, which is why the code calls FreeCopiedS().

Also note the EVAL keyword, which ignores the return value of a function.

UNSAFE MODULE Exec EXPORTS Main;

IMPORT Unix, M3toC;

VAR command := M3toC.CopyTtoS("ls");

BEGIN
  EVAL Unix.system(command);
  M3toC.FreeCopiedS(command);
END Exec.

MUMPS[edit]

ANSI MUMPS doesn't allow access to the operating system except possibly through the View command and $View function, both of which are implementation specific. Intersystems' Caché does allow you to create processes with the $ZF function, and if the permissions for the Caché process allow it you can perform operating system commands.

In Caché on OpenVMS in an FILES-11 filesystem ODS-5 mode this could work:

Set X=$ZF(-1,"DIR")

In GT.M on OpenVMS, the following will work:

ZSY "DIR"

GT.M on UNIX is the same:

ZSY "ls"

Note: $ZF in GT.M is Unicode version of $F[ind].

Nanoquery[edit]

shell("ls")

NetRexx[edit]

Translation of: Java
/* NetRexx */
options replace format comments java crossref symbols binary

import java.util.Scanner

runSample(arg)
return

-- 10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)10:43, 27 August 2022 (UTC)~~
method runSample(arg) private static
  parse arg command
  if command = '' then command = 'ls -oa' -- for Windows change to: 'cmd /C dir'
  do
    say 'Executing command:' command
    jprocess = Runtime.getRunTime().exec(command)
    jscanner = Scanner(jprocess.getInputStream())
    loop label scanning while jscanner.hasNext()
      say jscanner.nextLine()
      end scanning
  catch ex = IOException
    ex.printStackTrace()
  end
  return

NewLISP[edit]

(exec "ls")

Nim[edit]

import osproc

let exitCode = execCmd "ls"
let (output, exitCode2) = execCmdEx "ls"

Objective-C[edit]

Works with: GCC

NSTask runs an external process with explicit path and arguments.

void runls()
{
    [[NSTask launchedTaskWithLaunchPath:@"/bin/ls"
        arguments:@[]] waitUntilExit];
}

If you need to run a system command, invoke the shell:

void runSystemCommand(NSString *cmd)
{
    [[NSTask launchedTaskWithLaunchPath:@"/bin/sh"
        arguments:@[@"-c", cmd]]
        waitUntilExit];
}

Complete usage example:

Works with: Cocoa

Works with: GNUstep
#import <Foundation/Foundation.h>

void runSystemCommand(NSString *cmd)
{
    [[NSTask launchedTaskWithLaunchPath:@"/bin/sh"
        arguments:@[@"-c", cmd]]
        waitUntilExit];
}

int main(int argc, const char **argv)
{
    @autoreleasepool {

      runSystemCommand(@"ls");
    }
    return 0;
}

Or use the C method above.

OCaml[edit]

Just run the command:

Sys.command "ls"

To capture the output of the command:

#load "unix.cma"

let syscall cmd =
  let ic, oc = Unix.open_process cmd in
  let buf = Buffer.create 16 in
  (try
     while true do
       Buffer.add_channel buf ic 1
     done
   with End_of_file -> ());
  let _ = Unix.close_process (ic, oc) in
  (Buffer.contents buf)

let listing = syscall "ls" ;;


a more complete version which also returns the contents from stderr, and checks the exit-status, and where the environment can be specified:

let check_exit_status = function
  | Unix.WEXITED 0 -> ()
  | Unix.WEXITED r -> Printf.eprintf "warning: the process terminated with exit code (%d)\n%!" r
  | Unix.WSIGNALED n -> Printf.eprintf "warning: the process was killed by a signal (number: %d)\n%!" n
  | Unix.WSTOPPED n -> Printf.eprintf "warning: the process was stopped by a signal (number: %d)\n%!" n
;;

let syscall ?(env=[| |]) cmd =
  let ic, oc, ec = Unix.open_process_full cmd env in
  let buf1 = Buffer.create 96
  and buf2 = Buffer.create 48 in
  (try
     while true do Buffer.add_channel buf1 ic 1 done
   with End_of_file -> ());
  (try
     while true do Buffer.add_channel buf2 ec 1 done
   with End_of_file -> ());
  let exit_status = Unix.close_process_full (ic, oc, ec) in
  check_exit_status exit_status;
  (Buffer.contents buf1,
   Buffer.contents buf2)
val syscall : ?env:string array -> string -> string * string

Octave[edit]

system("ls");

Oforth[edit]

System cmd("pause")

Oz[edit]

{OS.system "ls" _}

A more sophisticated example can be found here.

PARI/GP[edit]

system("ls")

Pascal[edit]

Works with: Free_Pascal
Library: SysUtils
Program ExecuteSystemCommand;

uses
  SysUtils;
begin
  ExecuteProcess('/bin/ls', '-alh');
end.

PDP-11 Assembly[edit]

PDP-11 running Unix

; Execute a file - the equivalent of system() in stdio
;
; On entry, r1=>nul-terminated command string
; On exit,  VS=Couldn't fork
;           VC=Forked successfully, r0=return value
;
.CLIsystem
trap 2			; fork()
br   CLIchild		; Child process returns here
bcc  CLIparent		; Parent process returns here
mov  (sp)+,r1
tst  (sp)+
sev			; Couldn't fork, set V
rts  pc
.CLIparent
mov  r0,-(sp)		; Save child's PID
.CLIwait
trap 7			; wait()
cmp  r0,(sp)
beq  CLIfinished
cmp  r0,#&FFFF
bne  CLIwait		; Loop until child finished
.CLIfinished
tst  (sp)+		; Drop child's PID
mov  r1,r0		; R0=return value
mov  (sp)+,r1		; Restore R1
tst  (sp)+		; Drop original R0
swab r0			; Move return value to bottom byte
rts  pc

; CLI child process
; -----------------
.CLIchild
clr  -(sp)			; end of string array
mov  r1,-(sp)			; => command string
mov  #UXsh3,-(sp)		; => "-c"
mov  #UXsh2,-(sp)		; => "sh"
mov  #&890B,TRAP_BUF		; exec
mov  #UXsh1,TRAP_BUF+2		; => "/bin/sh"
mov  sp,TRAP_BUF+4		; => pointers to command strings
;mov  SV_ENVPTR,TRAP_BUF+6	; => "PATH=etc"
trap 0				; indir()
EQUW TRAP_BUF			; exec(shell, parameters)
add  #8,sp			; If we get back, we didn't fork, we spawned
mov  (sp)+,r1			; So, restore registers
clr  (sp)+			; and return exit value in R0
rts  pc

.UXsh1	EQUS "/bin/sh",0
.UXsh2	EQUS "sh",0
.UXsh3	EQUS "-c",0
ALIGN

.TRAP_BUF
EQUW 0
EQUW 0
EQUW 0
EQUW 0

So, call with, for example:

mov  #cmd_ls,r1		; => "ls" command string
jsr  pc,CLIsystem
...
.cmd_ls	EQUS "ls",0

Perl[edit]

my @results = qx(ls);  # run command and return STDOUT as a string

my @results = `ls`;    # same, alternative syntax

system "ls";           # run command and return exit status; STDOUT of command goes program STDOUT

print `ls`;            # same, but with back quotes

exec "ls";             # replace current process with another

See also: http://perldoc.perl.org/perlipc.html#Using-open()-for-IPC http://perldoc.perl.org/IPC/Open3.html

Phix[edit]

without js
string cmd = iff(platform()=WINDOWS?"dir":"ls")
system(cmd)
integer res = system_exec("pause",4)

system_exec allows you to specify whether you want a command shell or not, and whether to wait for a result. In the case of pause, the 4 signifies that we need a shell and we want to wait for it to complete.

PHP[edit]

The first line execute the command and the second line display the output:

@exec($command,$output);
echo nl2br($output);

Note:The '@' is here to prevent error messages to be displayed, 'nl2br' translate '\n' chars to 'br' in HTML.

Other:

$results = `ls`;
# runs command and returns its STDOUT as a string

system("ls");
# runs command and returns its exit status; its STDOUT gets output to our STDOUT

echo `ls`;
# the same, but with back quotes

passthru("ls");
# like system() but binary-safe

See also: proc_open()

PicoLisp[edit]

(call "ls")

Pike[edit]

int main(){
   // Process.run was added in Pike 7.8 as a wrapper to simplify the use of Process.create_process()
   mapping response = Process.run("ls -l");
   // response is now a map containing 3 fields
   // stderr, stdout, and exitcode. We want stdout.
   write(response["stdout"] + "\n");

   // with older versions of pike it's a bit more complicated:
   Stdio.File stdout = Stdio.File();
   Process.create_process(({"ls", "-l"}), ([ "stdout" : stdout->pipe() ]) );
   write(stdout->read() + "\n");
}

Plain English[edit]

A command is a string.
A parameter is a string.

To run:
Start up.
Execute "dir" on the command line.
Shut down.

To execute a command on the command line:
Put "/c " then the command into a parameter.
Null terminate the parameter.
Put "cmd" into a string.
Null terminate the string.
Call "shell32.dll" "ShellExecuteA" with nil and nil and the string's first and the parameter's first and nil and 1.

Pop11[edit]

The sysobey function runs commands using a shell:

sysobey('ls');

PowerShell[edit]

Since PowerShell is a shell, running commands is the default operation.

dir
ls
Get-ChildItem

are all equivalent (the first two are aliases for the third) but they are PowerShell-native commands. If one really needs to execute dir (which is no program but rather a built-in command in cmd.exe) this can be achieved by

cmd /c dir

Prolog[edit]

Works with: SWI Prolog
Works with: GNU Prolog
shell('ls').

PureBasic[edit]

ImportC "msvcrt.lib"
  system(str.p-ascii)
EndImport

If OpenConsole()
  system("dir & pause")
  
  Print(#CRLF$ + #CRLF$ + "Press ENTER to exit")
  Input()
  CloseConsole()
EndIf

Python[edit]

import os
exit_code = os.system('ls')       # Just execute the command, return a success/fail code
output    = os.popen('ls').read() # If you want to get the output data. Deprecated.

or

Works with: Python version 2.7 (and above)
import subprocess
# if the exit code was non-zero these commands raise a CalledProcessError
exit_code = subprocess.check_call(['ls', '-l'])   # Python 2.5+
assert exit_code == 0
output    = subprocess.check_output(['ls', '-l']) # Python 2.7+

or

Works with: Python version 2.4 (and above)
from subprocess import PIPE, Popen, STDOUT
p = Popen('ls', stdout=PIPE, stderr=STDOUT)
print p.communicate()[0]

Note: The latter is the preferred method for calling external processes, although cumbersome, it gives you finer control over the process.

or

Works with: Python version 2.2 (and above)
import commands
stat, out = commands.getstatusoutput('ls')
if not stat:
    print out

Quackery[edit]

Translation of: Python
$ \
import os
exit_code = os.system('ls') 
\ python
Output:
Quackery Quick Reference.pdf		extensionsX.qky
READ ME FIRST.txt			quackery.py
The Book of Quackery for print.pdf	sundry
The Book of Quackery.pdf		turtleduck.qky
bigrat.qky

R[edit]

system("ls")
output=system("ls",intern=TRUE)

Racket[edit]

#lang racket

;; simple execution of a shell command
(system "ls")

;; capture output
(string-split (with-output-to-string (λ() (system "ls"))) "\n")

;; Warning: passing random string to be run in a shell is a bad idea!
;; much safer: avoids shell parsing, arguments passed separately
(system* "/bin/ls" "-l")

;; avoid specifying the executable path
(system* (find-executable-path "/bin/ls") "-l")

Raku[edit]

(formerly Perl 6)

run "ls" orelse .die; # output to stdout

my @ls = qx/ls/;    # output to variable

my $cmd = 'ls';
@ls = qqx/$cmd/;  # same thing with interpolation

Raven[edit]

Back tick string is auto executed:

`ls -la` as listing

Or specifically on any string:

'ls -la' shell as listing

REBOL[edit]

; Capture output to string variable:

x: ""  call/output "dir" x
print x

; The 'console' refinement displays the command output on the REBOL command line.

call/console "dir *.r"
call/console "ls *.r"

call/console "pause"

; The 'shell' refinement may be necessary to launch some programs.

call/shell "notepad.exe"

Red[edit]

call/show %pause        ;The /show refinement forces the display of system's shell window (Windows only).
call/show %dir
call/show %notepad.exe

REXX[edit]

Since REXX is a shell scripting language, it's easy to execute commands:

"dir /a:d"

Ring[edit]

system("dir")

Ruby[edit]

string = `ls`
# runs command and returns its STDOUT as a string
string = %x{ls}
# ditto, alternative syntax

system "ls"
# runs command and returns its exit status; its STDOUT gets output to our STDOUT

print `ls`
#The same, but with back quotes

exec "ls"
# replace current process with another

# call system command and read output asynchronously
io = IO.popen('ls')
# ... later
io.each {|line| puts line}

Run BASIC[edit]

print shell$("ls")  ' prints the returned data from the OS
a$ =  shell$("ls")  ' holds returned data in a$

Rust[edit]

use std::process::Command;
fn main() {
    let output = Command::new("ls").output().unwrap_or_else(|e| {
        panic!("failed to execute process: {}", e)
    });
    println!("{}", String::from_utf8_lossy(&output.stdout));
}

Scala[edit]

import scala.sys.process.Process
Process("ls", Seq("-oa"))!

Scheme[edit]

Works with: Guile
Works with: Chicken Scheme
(system "ls")

Seed7[edit]

System commands can make a program unportable. Unix, Linux and BSD use the command ls, while Windows respectively DOS use the command dir. The format written by ls respectively dir depends on operating system and locale. The library osfiles.s7i defines the function readDir, which reads the contents of a directory in a portable way. ReadDir works independend from operating system and locale and supports also Unicode filenames. Anyway, the task was to use a system command, so here is the example:

$ include "seed7_05.s7i";
  include "shell.s7i";

const proc: main is func
  begin
    cmd_sh("ls");
  end func;

SETL[edit]

system("ls");

Sidef[edit]

# Pipe in read-only mode
%p(ls).open_r.each { |line|
    print line;
};

var str1 = `ls`;         # backtick: returns a string
var str2 = %x(ls);       # ditto, alternative syntax

Sys.system('ls');   # system: executes a command and prints the result
Sys.exec('ls');     # replaces current process with another

Slate[edit]

Run a command normally through the shell:

Platform run: 'ls'.

Run a command (this way takes advantage of the 'does not understand' message for the shell object and calls the Platform run: command above with a specific command):

shell ls: '*.slate'.

Smalltalk[edit]

Smalltalk system: 'ls'.

SQL PL[edit]

Works with: Db2 LUW

In Linux or UNIX:

!ls

Output:

db2 => !ls
adm	  ctrlhamirror	    fm.ip-10-0-0-85.reg  lib64	    profile.env  security64
adsm	  dasfcn	    function		 log	    python32	 spmlog
backup	  db2cshrc	    gskit		 map	    python64	 sqldbdir
bin	  db2dump	    hmonCache		 misc	    rdf		 tmp
bnd	  db2nodes.cfg	    include		 msg	    Readme	 tools
cfg	  db2profile	    infopop		 nodes	    ruby32	 uif
cfgcache  db2systm	    java		 nodes.reg  ruby64	 usercshrc
conv	  doc		    json		 pd	    samples	 userprofile
ctrl	  fm.db2-1.reg	    lib			 php32	    security
ctrlha	  fm.db2-model.reg  lib32		 php64	    security32

In Windows:

!dir

Standard ML[edit]

Just run the command:

OS.Process.system "ls"

Stata[edit]

Stata has a built-in dir command. However, it's also possible to run arbitrary external programs using the shell or winexec commands.

The command ! (or equivalently shell), opens a Windows console to run the command, while winexec does not.

!dir

* print a message and wait
!echo Ars Longa Vita Brevis & pause

* load Excel from Stata
!start excel

* run a Python program (Python must be installed and accessible in the PATH environment variable)
!python preprocessing.py

* load Windows Notepad
winexec notepad

Tcl[edit]

puts [exec ls]

This page uses "ls" as the primary example. For what it's worth, Tcl has built-in primitives for retrieving lists of files so one would rarely ever directly exec an ls command.

It is also possible to execute a system command by "open"ing it through a pipe from whence any output of the command can be read at any (later) time. For example:

set io [open "|ls" r]

would execute "ls" and pipe the result into the channel whose name is put in the "io" variable. From there one could receive it either line by line like this:

set nextline [gets $io]

or read the whole shebang in a fell swoop:

set lsoutput [read $io]

If the command is opened "rw", it is even possible to send it user input through the same handle, though care must be taken with buffering in that case.

exec C:/Windows/System32/taskmgr.exe &

Runs the Task Manager on Windows. If running from a Tcl/Tk Gui the [ & ] prevents blocking the Gui.

Toka[edit]

needs shell
" ls" system

TUSCRIPT[edit]

$$ MODE TUSCRIPT
system=SYSTEM ()
IF (system=="WIN") THEN
EXECUTE "dir"
ELSEIF (system.sw."LIN") THEN
EXECUTE "ls -l"
ENDIF

UNIX Shell[edit]

UNIX shells are designed to run system commands as a default operation.

ls

If one wishes to replace the shell process with some other command (chain into some command with no return) one can use the exec shell built-in command.

exec ls

Command substitution[edit]

One can also capture the command's standard output in a variable.

With Bourne Shell:

output=`ls`

With Korn Shell or any modern shell:

output=$(ls)
  • Note 1: in `ls`, these are "backticks" rather than quotes or apostrophes.
  • Note 2: the $(...) form works in all modern shells, including the Almquist Shell, Bash and any POSIX shell.
  • The old `backticks` can also be used in the newer shells, but their users prefer the $(...) form when discussing such things in e-mail, on USENET, or in other online forums (such as this wiki). The only reason to use `backticks` is in scripts for old Bourne Shell.

The `...` form is difficult to nest, but the $(...) form is very nestable.

output=`expr \`echo hi | wc -c\` - 1`
output=$(expr $(echo hi | wc -c) - 1)

Both forms, `backticks` and $(...), also work inside double-quoted strings. This prevents file name expansion and also prevents word splitting.

echo "Found: `grep 80/tcp /etc/services`"
echo "Found: $(grep 80/tcp /etc/services)"

C Shell[edit]

C Shell also runs system commands, and has an exec built-in command, exactly like Bourne Shell.

ls         # run command, return to shell
exec ls    # replace shell with command

`Backticks` are slightly different. When inside double quotes, as "`...`", C Shell splits words at newlines, like "line 1" "line 2" ..., but preserves spaces and tabs.

set output=( "`grep 80/ /etc/services`" )
echo "Line 1: $output[1]"
echo "Line 2: $output[2]"

Ursa[edit]

decl string<> arg
decl string<> output
decl iodevice iod

append "ls" arg
set iod (ursa.util.process.start arg)
set output (iod.readlines)

for (decl int i) (< i (size output)) (inc i)
        out output<i> endl console
end for

Ursala[edit]

The library function, ask, parameterized by a shell descriptor, such as bash, spawns a process that interacts with that shell by feeding it a list of commands, and returns a transcript of the interaction.

Note that the output from the spawned process is captured and returned only, not sent to the standard output stream of the parent.

Here is a self-contained command line application providing a limited replacement for the ls command.

#import std
#import cli

#executable ('parameterized','')

myls = <.file$[contents: --<''>]>@hm+ (ask bash)/0+ -[ls --color=no]-!

The color option is needed to suppress terminal escape sequences.

VBScript[edit]

Set objShell = CreateObject("WScript.Shell")
objShell.Run "%comspec% /K dir",3,True

Vedit macro language[edit]

system("dir", DOS)

The above does not work on 64-bit Windows versions which do not have 16-bit DOS emulation. In this case, you need to call cmd.exe explicitly:

system('cmd /k "dir"')

Visual Basic[edit]

Shelling out a sub task in Visual Basic is rather a pain if you need to wait for the task to complete, which is probably the usual case. But it is possible.

Attribute VB_Name = "mdlShellAndWait"
Option Explicit

Private Declare Function OpenProcess Lib "kernel32" _
    (ByVal dwDesiredAccess As Long, ByVal bInheritHandle As Long, _
    ByVal dwProcessId As Long) As Long

Private Declare Function GetExitCodeProcess Lib "kernel32" _
    (ByVal hProcess As Long, lpExitCode As Long) As Long

Private Const STATUS_PENDING = &H103&
Private Const PROCESS_QUERY_INFORMATION = &H400

'
' Little function go get exit code given processId
'
Function ProcessIsRunning( processId as Long ) as Boolean
    Dim exitCode as Long
    Call GetExitCodeProcess(lProcessId, exitCode)
    ProcessIsRunning = (exitCode = STATUS_PENDING)
End Function

' Spawn subprocess and wait for it to complete.
'   I believe that the command in the command line must be an exe or a bat file.
'   Maybe, however, it can reference any file the system knows how to "Open"
'
' commandLine is an executable. 
' expectedDuration - is for poping up a dialog for whatever
' infoText - text for progressDialog dialog

Public Function ShellAndWait( commandLine As String, _
    expectedDuration As Integer ) As Boolean
    
    Dim inst As Long
    Dim startTime As Long
    Dim expirationTime As Long
    Dim pid As Long
    Dim expiresSameDay As Boolean
    
    On Error GoTo HandleError

    'Deal with timeout being reset at Midnight ($hitForBrains VB folks)
    startTime = CLng(Timer)
    expirationTime = startTime + expectedDuration
    expiresSameDay = expirationTime < 86400
    If Not expiresSameDay Then
        expirationTime = expirationTime - 86400
    End If

    inst = Shell(commandLine, vbMinimizedNoFocus)
    
    If inst <> 0 Then
        pid = OpenProcess(PROCESS_QUERY_INFORMATION, False, inst)

        Do While ProcessIsRunning( pid)
            DoEvents
            If Timer > expirationTime And (expiresSameDay Or Timer < startTime) Then
                Exit Do
            End If
        Loop 
        ShellAndWait = True
    Else
        MsgBox ("Couldn't execute command: " & commandLine)
        ShellAndWait = False
    End If
        
    Exit Function
   
HandleError:
    MsgBox ("Couldn't execute command: " & commandLine)
    ShellAndWait = False
End Function

Sub SpawnDir()
   ShellAndWait("dir", 10)
End Sub

Visual Basic .NET[edit]

Works with: Visual Basic .NET version 9.0+
Module System_Command

    Sub Main()
        Dim cmd As New Process
        cmd.StartInfo.FileName = "cmd.exe"
        cmd.StartInfo.RedirectStandardInput = True
        cmd.StartInfo.RedirectStandardOutput = True
        cmd.StartInfo.CreateNoWindow = True
        cmd.StartInfo.UseShellExecute = False

        cmd.Start()

        cmd.StandardInput.WriteLine("dir")
        cmd.StandardInput.Flush()
        cmd.StandardInput.Close()

        Console.WriteLine(cmd.StandardOutput.ReadToEnd)
    End Sub

End Module

V (Vlang)[edit]

import  os

fn main() {
	result := os.execute('cmd /c dir')
	if result.output !='' {println(result.output)}
	else {println('Error: not working') exit(1)}
}

Wart[edit]

system "ls"

Wren[edit]

Wren CLI doesn't currently expose a way to execute a system command.

However, if Wren is embedded in (say) a suitable Go program, then we can ask the latter to do it for us.

/* run_system_command.wren */
class Command {
    foreign static exec(name, param) // the code for this is provided by Go
}

Command.exec("ls", "-lt")
System.print()
Command.exec("dir", "")

which we embed in the following Go program and run it.

Library: WrenGo
/* run_system_command.go*/
package main

import (
    wren "github.com/crazyinfin8/WrenGo"
    "log"
    "os"
    "os/exec"
)

type any = interface{}

func execCommand(vm *wren.VM, parameters []any) (any, error) {
    name := parameters[1].(string)
    param := parameters[2].(string)
    var cmd *exec.Cmd
    if param != "" {
        cmd = exec.Command(name, param)
    } else {
        cmd = exec.Command(name)
    }
    cmd.Stdout = os.Stdout
    cmd.Stderr = os.Stderr
    if err := cmd.Run(); err != nil {
        log.Fatal(err)
    }
    return nil, nil
}

func main() {
    vm := wren.NewVM()
    fileName := "run_system_command.wren"
    methodMap := wren.MethodMap{"static exec(_,_)": execCommand}
    classMap := wren.ClassMap{"Command": wren.NewClass(nil, nil, methodMap)}
    module := wren.NewModule(classMap)
    vm.SetModule(fileName, module)
    vm.InterpretFile(fileName)
    vm.Free()
}

x86 Assembly[edit]

Works with: NASM
Works with: Linux

32 bit

; Executes '/bin/ls'
; Build with:
;   nasm -felf32 execls.asm
;   ld -m elf_i386 execls.o -o execls

global  _start
section .text

_start:
    mov eax, 0x0B       ; sys_execve(char *str, char **args, char **envp)
    mov ebx, .path      ; pathname
    push DWORD 0
    push DWORD .path
    lea ecx, [esp]      ; arguments [pathname]
    xor edx, edx        ; environment variables []
    int 0x80            ; syscall
.path:
    db  '/bin/ls', 0x00

Yabasic[edit]

system("dir")
//It will return the exit code of the command; its output (if any) will be lost.


print system$("dir")
//Returns the output as a large string.

zkl[edit]

System.cmd(System.isWindows and "dir" or "ls")

ZX Spectrum Basic[edit]

The ZX Spectrum uses a ROM based basic interpreter, so every statement within the program is a system command. If a command without a line number is typed, whilst the computer is in a ready state, the command gets executed immediately:

PAUSE 100