Command-line arguments: Difference between revisions

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Retrieve the list of command-line arguments given to the program. For programs that only print the arguments when run directly, see Scripted main.

ALGOL 68

Works with: ALGOL 68G version Any - tested with release mk15-0.8b.fc9.i386 - argc and argv are not part of the standard's prelude

<lang algol68>main:(

 FOR i TO argc DO
   printf(($"the argument #"g(-0)" is "gl$, i, argv(i)))
 OD

)</lang> Linux command:

/usr/bin/a68g Command-line_arguments.a68 - 1 2 3 ...

Output:

the argument #1 is /usr/bin/a68g
the argument #2 is ./Command-line_arguments.a68
the argument #3 is -
the argument #4 is 1
the argument #5 is 2
the argument #6 is 3
the argument #7 is ...

From the AutoHotkey documentation: "The script sees incoming parameters as the variables %1%, %2%, and so on. In addition, %0% contains the number of parameters passed (0 if none). " <lang autohotkey>Loop %0% ; number of parameters

 params .= %A_Index% . A_Space

If params !=

 MsgBox, %0% parameters were passed:`n`n %params%

Else

 Run, %A_AhkPath% "%A_ScriptFullPath%" -c "\"alpha beta\"" -h "\"gamma\""</lang>

AWK

<lang awk>#!/usr/bin/awk -f

BEGIN {

 print "There are " ARGC "command line parameters"
 for(l=1; l<ARGC; l++) {
   print "Argument " l " is " ARGV[l]
 }

}</lang>

BASIC

Works with: QuickBASIC

For most older BASICs that supply the keyword COMMAND$, all arguments are returned in a single string that must then be parsed inside the program. (Unlike modern BASICs, there is often no easy way to retrieve the program's name.)

<lang qbasic>PRINT "args: '"; COMMAND$; "'"</lang>

Sample output:

args: 'This is a test.'

Works with: FreeBASIC

FreeBASIC supplies three ways to retrieve the arguments: COMMAND$ (which works identically to QuickBASIC's COMMAND$), COMMAND$() (a string array which works like C's argv[]), and __FB_ARGV__ (an array of pointers which works even more like C's argv[]) and __FB_ARGC__ (which works like C's argc).

<lang freebasic>DIM i AS INTEGER

PRINT COMMAND$

PRINT "This program is named "; COMMAND$(0) i = 1 DO WHILE(LEN(COMMAND$(i)))

   PRINT "The argument "; i; " is "; COMMAND$(i)
   i = i + 1

LOOP

FOR i = 0 TO __FB_ARGC__ - 1

       PRINT "arg "; i; " = '"; *__FB_ARGV__[i]; "'"

NEXT i</lang>

Sample output:

C:\>cla 1 2 3
1 2 3
This program is named cla
The argument  1 is 1
The argument  2 is 2
The argument  3 is 3
arg  0 = 'cla'
arg  1 = '1'
arg  2 = '2'
arg  3 = '3'

Batch File

Works with: Windows NT version 4 or later (includes Windows XP and onward)

<lang dos>@echo off setlocal enabledelayedexpansion

set Count=0

loop

if not "%1"=="" (

  set /a count+=1
  set parameter[!count!]=%1
  shift
  goto loop

)

for /l %%a in (1,1,%count%) do (

  echo !parameter[%%a]!

)</lang>

Another way of doing it

<lang dos>::args2.cmd @echo off setlocal enabledelayedexpansion set fn=%~f0 set p0=%~0 set p*=%* set /a c=1

loop

if @%1==@ goto done set p%c%=%~1 set /a c=c+1 shift goto loop

done

set /a c=c-1 set p#=%c% echo fn=%fn% echo p0=%p0% echo p*=%p*% echo p#=%p#% for /l %%i in (1,1,%p#%) do ( echo p%%i=!p%%i! )</lang>

Invocation:

BBC BASIC

Works with: BBC BASIC for Windows

<lang bbcbasic>PRINT @cmd$</lang>

Bracmat

When Bracmat is started with one or more arguments, each argument is evaluated as if it were a Bracmat expression unless an argument (for example the first one) consumes the next argument(s) by calling arg$. Each invocation of arg$ pops one argument from the remaining list of arguments. Calling arg$ when no more arguments are available results in failure. The following program iterates over all arguments following the currently evaluated argument and outputs the argument to standard output. <lang>whl'(arg$:?a&out$(str$("next arg=" !a)))</lang> Now run Bracmat with this program as the first argument in a DOS environment:

bracmat "whl'(arg$:?a&out$(str$(\"next arg=\" !a)))" "a" /b -c 2+3 'd;' "out$(\"13+7=\" 13+7)"

Instead of starting in interactive mode, Bracmat interprets the first argument, which consumes all following arguments. This is output to standard output:

next arg=a
next arg=/b
next arg=-c
next arg=2+3
next arg='d;'
next arg=out$("13+7=" 13+7)

If given an argument index, arg$<arg index> returns the indexed argument without consuming any argument.

bracmat "0:?n&whl'(arg$!n:?a&out$str$(arg[ !n \"]=\" !a)&1+!n:?n)" "a" /b -c 2+3 'd;' "out$(\"13+7=\" 13+7)"

Output:

arg[0]=bracmat
arg[1]=0:?n&whl'(arg$!n:?a&out$str$(arg[ !n "]=" !a)&1+!n:?n)
arg[2]=a
arg[3]=/b
arg[4]=-c
arg[5]=2+3
arg[6]='d;'
arg[7]=out$("13+7=" 13+7)
13+7= 20

The last line demonstrates that not only the first argument is evaluated, but also the following arguments.

If Bracmat is run without arguments, Bracmat starts in interactive mode. In that situation calling arg$ fails. The same is true if Bracmat is compiled as a shared library (DLL or so).

C

Command line arguments are passed to main. Since the program name is also passed as "argument", the provided count is actually one more than the number of program arguments. Traditionally the argument count is named argc and the array of argument strings is called argv, but that's not mandatory; any (non-reserved) name will work just as well. It is, however, a good idea to stick to the conventional names.

Be careful on systems that use Unicode or other multibyte character sets. You may need to use a type of _wchar* and multi-byte-character-set-aware versions of printf.

<lang c>#include <stdlib.h>

include <stdio.h>

int main(int argc, char* argv[]) {

 int i;
 (void) printf("This program is named %s.\n", argv[0]);
 for (i = 1; i < argc; ++i)
   (void) printf("the argument #%d is %s\n", i, argv[i]);
 return EXIT_SUCCESS;

}</lang>

C++

Command line arguments are passed the same way as in C.

This example uses iostream. Traditional C I/O also works.

<lang cpp>#include <iostream>

int main(int argc, char* argv[]) {

 std::cout << "This program is named " << argv[0] << std::endl;
 std::cout << "There are " << argc-1 << " arguments given." << std::endl;
 for (int i = 1; i < argc; ++i)
   std::cout << "the argument #" << i << " is " << argv[i] << std::endl;

 return 0;

}</lang>

C#

There are at least two methods to access the command-line arguments. The first method is to access the string array passed to Main. This method only accesses the arguments and not the path to the executable. <lang csharp>using System;

namespace RosettaCode {

   class Program {
       static void Main(string[] args) {
           for (int i = 0; i < args.Length; i++)
               Console.WriteLine(String.Format("Argument {0} is '{1}'", i, args[i]));
       }
   }

}</lang>

The second method is to call the Environment.GetCommandLineArgs function. This method also returns the path to the executable as args[0] followed by the actual command line arguments. <lang csharp>using System;

namespace RosettaCode {

   class Program {
       static void Main() {
           string[] args = Environment.GetCommandLineArgs();
           for (int i = 0; i < args.Length; i++)
               Console.WriteLine(String.Format("Argument {0} is '{1}'", i, args[i]));
       }
   }

}</lang>

Clean

getCommandLine from the module ArgEnv returns an array of command-line arguments (the first element is the name of the program).

<lang clean>import ArgEnv

Start = getCommandLine</lang>

Clojure

The value of *command-line-args* is a sequence of the supplied command line arguments, or nil if none were supplied.

<lang Clojure>(dorun (map println *command-line-args*))</lang>

COBOL

The COBOL standard appears to say nothing regarding the retrieval of command-line arguments, although methods of retrieving them are provided by most vendors.

Works with: OpenCOBOL

Works with: Visual COBOL

Getting the arguments in one go, exactly as they were passed in: <lang cobol> IDENTIFICATION DIVISION.

      PROGRAM-ID. accept-all-args.
      
      DATA DIVISION.
      WORKING-STORAGE SECTION.
      01  args                   PIC X(50).
      
      PROCEDURE DIVISION.
      main-line.
          ACCEPT args FROM COMMAND-LINE
          DISPLAY args
          
          GOBACK
          .</lang>

Getting the arguments one at a time, with arguments being split by whitespace if not in quotes: <lang cobol> IDENTIFICATION DIVISION.

      PROGRAM-ID. accept-args-one-at-a-time.
      
      DATA DIVISION.
      WORKING-STORAGE SECTION.
      01  arg                 PIC X(50) VALUE SPACES.
      
      PROCEDURE DIVISION.
          ACCEPT arg FROM ARGUMENT-VALUE
          PERFORM UNTIL arg = SPACES
              DISPLAY arg
              MOVE SPACES TO arg
              ACCEPT arg FROM ARGUMENT-VALUE
          END-PERFORM
          
          GOBACK
          .</lang>

CoffeeScript

Works with: Node.js

<lang coffeescript> console.log arg for arg in process.argv </lang>

Common Lisp

The Common Lisp standard does not specify anything relating to external invocation of a Common Lisp system. The method for getting command-line arguments varies by implementation.

The following function could be used to create a uniform way to access the arguments:

<lang lisp>(defun argv ()

 (or
  #+clisp (ext:argv)
  #+sbcl sb-ext:*posix-argv*
  #+abcl ext:*command-line-argument-list*
  #+clozure (ccl::command-line-arguments)
  #+gcl si:*command-args*
  #+ecl (loop for i from 0 below (si:argc) collect (si:argv i))
  #+cmu extensions:*command-line-strings*
  #+allegro (sys:command-line-arguments)
  #+lispworks sys:*line-arguments-list*
  nil))</lang>

D

<lang d>void main(in string[] args) {

   import std.stdio;

   foreach (immutable i, arg; args[1 .. $])
       writefln("#%2d : %s", i + 1, arg);

}</lang>

Déjà Vu

Command line arguments are found in !args and !opts.

<lang dejavu>for i range 0 -- len !args: print\( "Argument #" i " is " ) . get-from !args i

if has !opts :c: !print "Ah, the -c option."

if has !opts :four: !. get-from !opts :four</lang>

Output:

$ vu args-3.deja one two -c three --four=five
Argument #0 is "args-3.deja"
Argument #1 is "one"
Argument #2 is "two"
Argument #3 is "three"
Ah, the -c option.
"five"

The order of command line options is lost.

Delphi

<lang delphi>// The program name and the directory it was called from are in // param[0] , so given the axample of myprogram -c "alpha beta" -h "gamma"

 for x := 0 to paramcount do
     writeln('param[',x,'] = ',param[x]);

// will yield ( assuming windows and the c drive as the only drive) :

// param[0] = c:\myprogram // param[1] = -c // param[2] = alpha beta // param[3] = -h // param[4] = gamma </lang>

E

<lang e>interp.getArgs()</lang>

Eiffel

This class inherits functionality for dealing with command line arguments from class ARGUMENTS. It uses the feature separate_character_option_value to return the values by option name for each of the two arguments.

<lang eiffel >class

   APPLICATION

inherit

   ARGUMENTS

create

   make

feature {NONE} -- Initialization

   make
           -- Print values for arguments with options 'c' and 'h'.
       do
           print ("Command line argument value for option 'c' is: ")
           print (separate_character_option_value ('c') + "%N")
           print ("Command line argument value for option 'h' is: ")
           print (separate_character_option_value ('h') + "%N")
           io.read_line    -- Keep console window open
       end

end</lang>

Output (for command line arguments: -c "alpha beta" -h "gamma"):

Command line argument value for option 'c' is: alpha beta
Command line argument value for option 'h' is: gamma

Emacs Lisp

!/usr/bin/env emacs --script

(dolist (arg command-line-args-left) (message arg)) </lang>

Erlang

When used as a script language the arguments is a list to the main/1 function. When compiled use init:get_arguments/0 <lang erlang>3> init:get_arguments().</lang> result <lang erlang>[{root,["/usr/erlang/erl5.5"]}, {progname,["erl"]}, {home,["/home/me"]}, {c,["alpha beta"]}, {h,["gamma"]}]</lang>

init:get_argument(name) can be used to fetch value of a particular flag

<lang erlang>4> init:get_argument(h). {ok,"gamma"} 5> init:get_argument(c). {ok,"alpha beta"}</lang>

Euphoria

<lang Euphoria>constant cmd = command_line() printf(1,"Interpreter/executable name: %s\n",{cmd[1]}) printf(1,"Program file name: %s\n",{cmd[2]}) if length(cmd)>2 then

 puts(1,"Command line arguments:\n")
 for i = 3 to length(cmd) do
   printf(1,"#%d : %s\n",{i,cmd[i]}) 
 end for

end if</lang>

F#

The entry-point function accepts the comment line arguments as an array of strings. The following program will print each argument on a separate line. <lang fsharp>#light [<EntryPoint>] let main args =

   Array.iter (fun x -> printfn "%s" x) args
   0</lang>

Factor

USING: io sequences command-line ;
(command-line) [ print ] each

Fancy

<lang fancy>ARGV each: |a| {

 a println # print each given command line argument

}</lang>

Fantom

<lang fantom> class Main {

 public static Void main (Str[] args) 
 {
   echo ("command-line args are: " + args)
 }

} </lang>

Forth

Access to command line arguments is not a standard feature of Forth, since it is designed to be used without an operating system. The popular GNU implementation gforth runs from a shell and can access command line arguments similar to C: variable argc contains the count (including the command itself) and arg is a function that returns the nth argument as a string.

Works with: gforth version 0.6.2

<lang forth>\ args.f: print each command line argument on a separate line

main

 argc @ 0 do i arg type cr loop ;

main bye</lang>

Here is output from a sample run. <lang forth>$ gforth args.f alpha "beta gamma" delta gforth args.f alpha beta gamma delta $</lang>

Fortran

Works with: Fortran version 2003 and later

<lang fortran>program command_line_arguments

 implicit none
 integer, parameter :: len_max = 256
 integer :: i , nargs
 character (len_max) :: arg
 
 nargs = command_argument_count()
 !nargs = iargc()
 do i = 0, nargs
   call get_command_argument (i, arg)
   !call getarg (i, arg)
   write (*, '(a)') trim (arg)
 end do

end program command_line_arguments </lang> Note: This sample uses the Fortran 2003 intrinsic routines command_argument_count and get_command_argument instead of the nonstandard extensions iargc and getarg. Most Fortran compilers support both.

Sample usage: <lang>> ./a.out -c "alpha beta" -h "gamma" ./a.out -c alpha beta -h gamma</lang>

Frink

Arguments to a program are available in the ARGS array variable. <lang frink> println[ARGS] </lang>

Gambas

<lang gambas>PUBLIC SUB main()

 DIM l AS Integer
 DIM numparms AS Integer
 DIM parm AS String
 numparms = Application.Args.Count
 FOR l = 0 TO numparms - 1
   parm = Application.Args[l]
   PRINT l; " : "; parm
 NEXT

END SUB</lang>

Go

<lang go>package main import (

 "fmt"
 "os"

)

func main() {

 for i, x := range os.Args {
   if i == 0 {
     fmt.Printf("This program is named %s.\n", x)
   } else {
     fmt.Printf("the argument #%d is %s\n", i, x)
   }
 }

}</lang>

Groovy

Command-line arguments are accessible via the args list variable. The following is saved as the file "Echo.groovy": <lang groovy>println args</lang>

The existence of command-line arguments presupposes the existence of a command line interpreter. The following test runs were entered in a cygwin bash shell in a Microsoft Windows XP system:

$ groovy Echo this is an argument list
[this, is, an, argument, list]
$ groovy Echo -x alkfrew4oij -cdkjei +22
[-x, alkfrew4oij, -cdkjei, +22]
$

For more sophisticated command-line option and option-argument parsing use the CliBuilder (command-line interface builder) library, which extends the functionality of the Java-based Apache Commons CLI library to Groovy.

Haskell

Defined by the System module, getArgs :: IO [String] provides the command-line arguments in a list.

myprog.hs: <lang haskell>import System main = getArgs >>= print</lang>

myprog a -h b c
=> ["a","-h","b","c"]

HicEst

<lang hicest>DO i = 2, 100 ! 1 is HicEst.exe

 EDIT(Text=$CMD_LINE, SePaRators='-"', ITeM=i, IF ' ', EXit, ENDIF, Parse=cmd, GetPosition=position)
 IF(position > 0) WRITE(Messagebox) cmd

ENDDO</lang>

Icon and Unicon

Command line parameters are passed to Icon/Unicon programs as a list of strings. <lang Icon>procedure main(arglist) every write(!arglist) end</lang>

Library: Icon Programming Library

includes options that parses the command line as switches and arguments and returns the results in a table.

Io

<lang io>System args foreach(a, a println)</lang>

Ioke

<lang ioke>System programArguments each(println)</lang>

J

The global ARGV holds the command line arguments. Thus, a program to display them:

Java

<lang java>public class Arguments {

 public static void main(String[] args) {
    System.out.println("There are " + args.length + " arguments given.");
    for(int i = 0; i < args.length; i++) 
       System.out.println("The argument #" + (i+1) + " is " + args[i] + " and is at index " + i);
 }

}</lang>

For more sophisticated command-line option and option-argument parsing use the Apache Commons CLI (command-line interface) library.

JavaScript

Works with: JScript

<lang javascript>var objArgs = WScript.Arguments; for (var i = 0; i < objArgs.length; i++)

  WScript.Echo(objArgs.Item(i));</lang>

Works with: JScript.NET (compiled with jsc.exe)

<lang javascript>import System; var argv:String[] = Environment.GetCommandLineArgs(); for (var i in argv)

 print(argv[i]);</lang>

Works with: Rhino

Works with: SpiderMonkey

<lang javascript>for (var i = 0; i < arguments.length; i++)

   print(arguments[i]);</lang>

Lasso

<lang lasso>#!/usr/bin/lasso9

iterate($argv) => {

 stdoutnl("Argument " + loop_count + ": " + loop_value)

}</lang> Output: <lang shell>$ lasso9 arguments.lasso -c "alpha beta" -h "gamma" Argument 1: arguments.lasso Argument 2: -c Argument 3: alpha beta Argument 4: -h Argument 5: gamma</lang>

LFE

To demonstrate this, we can start the LFE REPL up with the parameters for this example: <lang shell> $ ./bin/lfe -pa ebin/ -c "alpha beta" -h "gamma" </lang>

Once we're in the shell, we can get all the initializing arguments with this call: <lang lisp> > (: init get_arguments) (#(root ("/opt/erlang/r15b03"))

#(progname ("erl"))
#(home ("/Users/oubiwann"))
#(user ("lfe_boot"))
#(pa ("ebin/"))
#(c ("alpha beta"))
#(h ("gamma")))

</lang>

We can also get specific arguments if we know their keys: <lang lisp> > (: init get_argument 'c)

(ok (("alpha beta")))

> (: init get_argument 'h)

(ok (("gamma")))

</lang>

Liberty BASIC

<lang lb>print CommandLine$</lang>

Logo

Works with: UCB Logo version 5.6

If the command line to a logo script is written

logo file.logo - arg1 arg2 arg3

Then the arguments after the "-" are found in a list in variable :COMMAND.LINE <lang logo>show :COMMAND.LINE [arg1 arg2 arg3]</lang> Alternatively, make the first line of an executable logo script:

#! /usr/bin/logo -

to be able to invoke the script with arguments.

file.logo arg1 arg2 arg3

LSE64

<lang lse64>argc , nl # number of arguments (including command itself) 0 # argument dup arg dup 0 = || ,t 1 + repeat drop</lang>

Lua

The lua scripting language does not use argc and argv conventions for the command line parameters. Instead, the command line parameters to the main script are provided through the global table arg. The script name is placed into element zero of arg, and the script parameters go into the subsequent elements:

<lang lua>print( "Program name:", arg[0] )

print "Arguments:" for i = 1, #arg do

   print( i," ", arg[i] )

end</lang>

Mathematica

myprogram: <lang Mathematica>#!/usr/local/bin/MathematicaScript -script $CommandLine</lang> Output:

{myprogram,-c,alpha beta,-h,gamma}

Mercury

<lang>

- module cmd_line_args.

- interface.

- import_module io.

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

- implementation.

- import_module int, list, string.

main(!IO) :-

   io.progname("", ProgName, !IO),
   io.format("This program is named %s.\n", [s(ProgName)], !IO),
   io.command_line_arguments(Args, !IO),
   list.foldl2(print_arg, Args, 1, _, !IO).

- pred print_arg(string::in, int::in, int::out, io::di, io::uo) is det.

print_arg(Arg, ArgNum, ArgNum + 1, !IO) :-

   io.format("the argument #%d is %s\n", [i(ArgNum), s(Arg)], !IO).

</lang>

MMIX

<lang mmix>argv IS $1 argc IS $0 i IS $2

      LOC   #100

Main LOC @

      SETL  i,1               % i = 1

Loop CMP $3,argc,2 % argc < 2 ?

      BN    $3,1F             % then jump to end
      XOR   $255,$255,$255    % clear $255
      8ADDU $255,i,argv       % i*8 + argv
      LDOU  $255,$255,0       % argv[i]
      TRAP  0,Fputs,StdOut    % write the argument
      GETA  $255,NewLine      % add a newline
      TRAP  0,Fputs,StdOut
      INCL  i,1               % increment index
      SUB   argc,argc,1       % argc--
      BP    argc,Loop         % argc > 0? then Loop

1H LOC @

      XOR   $255,$255,$255    % exit(0)
      TRAP  0,Halt,0

NewLine BYTE #a,0</lang>

Modula-2

<lang modula2>MODULE try;

FROM Arguments IMPORT GetArgs, ArgTable, GetEnv; FROM InOut IMPORT WriteCard, WriteLn, WriteString;

VAR count, item : SHORTCARD;

     storage            : ArgTable;

BEGIN

  GetArgs (count, storage);
  WriteString ('Count =');     WriteCard (count, 4);   WriteLn;
  item := 0;
  REPEAT
     WriteCard (item, 4);
     WriteString (' :  ');
     WriteString (storage^ [item]^);
     WriteLn;
     INC (item)
  UNTIL item = count

END try.</lang> Example: <lang Modula-2> jan@Beryllium:~/modula/test$ try jantje zag eens pruimen hangen Count = 6

  0 :  try
  1 :  jantje
  2 :  zag
  3 :  eens
  4 :  pruimen
  5 :  hangen

</lang>

Modula-3

Command line parameters are accessed using the Params module. <lang modula3>MODULE Args EXPORTS Main;

IMPORT IO, Params;

BEGIN

 IO.Put(Params.Get(0) & "\n");
 IF Params.Count > 1 THEN
   FOR i := 1 TO Params.Count - 1 DO
     IO.Put(Params.Get(i) & "\n");
   END;
 END;

END Args.</lang>

Output:

martin@thinkpad:~$ ./prog
./prog
martin@thinkpad:~$ ./prog 10
./prog
10
martin@thinkpad:~$ ./prog 10 20
./prog
10
20

Nemerle

<lang Nemerle>using System; using System.Console;

module CLArgs {

   Main(args : array[string]) : void
   {
       foreach (arg in args) Write($"$arg "); // using the array passed to Main(), everything after the program name
       Write("\n");
       
       def cl_args = Environment.GetCommandLineArgs(); // also gets program name
       foreach (cl_arg in cl_args) Write($"$cl_arg ");
   }

}</lang>

NetRexx

In a stand-alone application NetRexx places the command string passed to it in a variable called arg. <lang NetRexx>/* NetRexx */ -- sample arguments: -c "alpha beta" -h "gamma" say "program arguments:" arg </lang> Output:

program arguments: -c "alpha beta" -h "gamma"

Objeck

<lang objeck> bundle Default {

 class Line {
   function : Main(args : String[]) ~ Nil {
     each(i : args) {
       args[i]->PrintLine();
      };
   }
 }

} </lang>

Objective-C

In addition to the regular C mechanism of arguments to main(), Objective-C also has another way to get the arguments as string objects inside an array object: <lang objc>NSArray *args = [[NSProcessInfo processInfo] arguments]; NSLog(@"This program is named %@.", [args objectAtIndex:0]); NSLog(@"There are %d arguments.", [args count] - 1); for (i = 1; i < [args count]; ++i){

   NSLog(@"the argument #%d is %@", i, [args objectAtIndex:i]);

}</lang>

OCaml

The program name is also passed as "argument", so the array length is actually one more than the number of program arguments.

<lang ocaml>let () =

 Printf.printf "This program is named %s.\n" Sys.argv.(0);
 for i = 1 to Array.length Sys.argv - 1 do
   Printf.printf "the argument #%d is %s\n" i Sys.argv.(i)
 done</lang>

Using the Arg module

<lang ocaml>(* default values *) let somebool = ref false let somestr = ref "" let someint = ref 0

let usage = "usage: " ^ Sys.argv.(0) ^ " [-b] [-s string] [-d int]"

let speclist = [

   ("-b", Arg.Set somebool, ": set somebool to true");
   ("-s", Arg.Set_string somestr, ": what follows -s sets some string");
   ("-d", Arg.Set_int someint, ": some int parameter");
 ]

let () =

 (* Read the arguments *)
 Arg.parse
   speclist
   (fun x -> raise (Arg.Bad ("Bad argument : " ^ x)))
   usage;

 Printf.printf " %b %d '%s'\n" !somebool !someint !somestr;

</lang>

% ocaml arg.ml --help
usage: tmp.ml [-b] [-s string] [-d int]
  -b : set somebool to true
  -s : what follows -s sets some string
  -d : some int parameter
  --help  Display this list of options

% ocaml arg.ml -d 4 -b -s blabla
 true 4 'blabla'

% ocaml arg.ml
 false 0 ''

Oz

Raw arguments

Like in C, but without the program name: <lang oz>functor import Application System define

  ArgList = {Application.getArgs plain}
  {ForAll ArgList System.showInfo}
  {Application.exit 0}

end</lang>

Preprocessed arguments

<lang oz>functor import Application System define

  ArgSpec =
  record(
     c(type:string single      %% option "--c" expects a string, may only occur once,

optional:false char:&c) %% is not optional and has a shortcut "-c"

     h(type:string single      %% option "--h" expects a string, may only occur once,

default:"default h" %% is optional and has a default value if not given char:&h) %% and has a shortcut "-h"

     )
  Args = {Application.getArgs ArgSpec}
  {System.showInfo Args.c}
  {System.showInfo Args.h}
  {Application.exit 0}

end</lang>

Pascal

Depends on implementation.

Perl

Works with: Perl version 5.x

@ARGV is the array containing all command line parameters

<lang perl>my @params = @ARGV; my $params_size = @ARGV; my $second = $ARGV[1]; my $fifth = $ARGV[4];</lang>

If you don't mind importing a module:

<lang perl>use Getopt::Long; GetOptions (

   'help|h'     => \my $help,
   'verbose|v'  => \my $verbose,

);</lang>

Perl 6

Perl 5's @ARGV is available as @*ARGS. Alternatively, if you define a subroutine named MAIN, Perl will automatically process @*ARGS according to Unix conventions and MAIN's signature (or signatures, if your MAIN is a multi sub) and then call MAIN with appropriate arguments; see Synopsis 6 or [1].

<lang perl6># with arguments supplied $ perl6 -e 'sub MAIN($x, $y) { say $x + $y }' 3 5 8

missing argument:

$ perl6 -e 'sub MAIN($x, $y) { say $x + $y }' 3 Usage: -e '...' x y</lang>

If the program is stored in a file, the file name is printed instead of -e '...'.

PHP

When PHP is run from the command line, the special variables $argv and $argc contain the array of arguments, and the number of arguments, respectively. The program name is passed as the first argument.

PicoLisp

There are three ways to handle command-line arguments in PicoLisp:

1. Obtain all arguments as a list of strings via 'argv'

2. Fetch each argument individually with 'opt'

3. Use the built-in command-line interpretation, where arguments starting with a hyphen are executed as functions.

Here we use the third option, as it is not so obvious, sometimes more flexible, and in fact the most commonly used one for application development.

We define 'c' and 'h' as functions, which retrieve their argument with 'opt', and then 'load' all remaining command line arguments. <lang PicoLisp>#!/usr/bin/picolisp /usr/lib/picolisp/lib.l

(de c ()

  (prinl "Got 'c': " (opt)) )

(de h ()

  (prinl "Got 'h': " (opt)) )

(load T) (bye)</lang> Output:

$ ./myprogram -c "alpha beta" -h "gamma"
Got 'c': alpha beta
Got 'h': gamma

PL/I

<lang pli> /* The entire command line except the command word itself is passed */ /* to the parameter variable in PL/I. */ program: procedure (command_line) options (main);

  declare command_line character (100) varying;

...

end program; </lang>

Pop11

variable poparglist contains list of command line arguments (as strings). One can use iteration over list to process then (for example print).

<lang pop11>lvars arg; for arg in poparglist do

  printf(arg, '->%s<-\n');

endfor;</lang>

PowerBASIC

For versions of PowerBASIC prior to PB/Win 9 and PB/CC 5, the only option available is identical to the one used by QuickBASIC above: <lang powerbasic>? "args: '"; COMMAND$; "'"</lang>

Current versions of PowerBASIC (with the likely exception of PB/DOS) include COMMAND$() that works similarly to FreeBASIC's COMMAND$(), except that you can't retrieve the application's name: <lang powerbasic>'these two both return ALL args ? COMMAND$ ? COMMAND$(0)

DO WHILE(LEN(COMMAND$(i)))

   PRINT "The argument "; i; " is "; COMMAND$(i)
   i = i + 1

LOOP</lang>

PowerShell

In PowerShell the arguments to a script can be accessed with the $args array: <lang powershell>$i = 0 foreach ($s in $args) {

   Write-Host Argument (++$i) is $s

}</lang>

Pure

Arguments are in global variables, argc and argv.

<lang pure> using system;

printf "There are %d command line argumants\n" argc; puts "They are " $$ map (puts) argv; </lang>

PureBasic

Reading all parameters

You can easily read all parameters by using ProgramParameter() without argument. <lang PureBasic>If OpenConsole()

 Define n=CountProgramParameters()
 PrintN("Reading all parameters")
 While n
   PrintN(ProgramParameter())
   n-1
 Wend
 Print(#CRLF$+"Press Enter")
 Input()
 CloseConsole()

EndIf</lang>

Reading specific parameters

You can specify which parameter 'n' to read. <lang PureBasic>If OpenConsole()

 Define n
 PrintN("Reading specific pameters")
 For n=0 To CountProgramParameters()
   PrintN(ProgramParameter(n))
 Next
 Print(#CRLF$+"Press Enter")
 Input()
 CloseConsole()

EndIf</lang>

Python

sys.argv is a list containing all command line arguments, including the program name. Typically you slice the list to access the actual command line argument:

<lang python>import sys program_name = sys.argv[0] arguments = sys.argv[1:] count = len(arguments)</lang>

When running a module by invoking Python, the Python interpreter processes and removes some of the arguments, and the module cannot access them. To process command line arguments, run the module directly. sys.argv is a copy of the command line arguments; modifying sys.argv will not change the arguments seen by other processes, e.g. ps. (In other words sys.argv is an object which contains a copy of the process' command line arguments ... modifying that copy is only visible from within the Python program and not externally).

For powerful option parsing capabilities check out the optparse module.

R

Following adapted from this post by Forester:

Suppose you want to call your script test.r with the arguments a=1 b=c(2,5,6), where b is a numeric vector. Suppose you also want to redirect your output to test.out (not that you have a choice--I still don't know how to make R send shell-script output to stdout). You would then run

<lang R>R CMD BATCH --vanilla --slave '--args a=1 b=c(2,5,6)' test.r test.out</lang>

from the commandline, with the following text in test.r:

<lang R># Read the commandline arguments args <- (commandArgs(TRUE))

args is now a list of character vectors
First check to see if any arguments were passed,
then evaluate each argument.

if (length(args)==0) {

   print("No arguments supplied.")
   # Supply default values
   a <- 1
   b <- c(1,1,1)

} else {

   for (i in 1:length(args)) {
        eval(parse(text=argsi))
   }

} print(a*2) print(b*3)</lang>

(possibly preceding code that actually does something :-) Your output test.out would then contain (e.g., if you cat it)

[1] 2
[1]  6 15 18
> proc.time()
   user  system elapsed 
  0.168   0.026   0.178

If you know how to get the output

sent to stdout (i.e., as is normal with shell scripts)
done without the profiling

please update this example!

Racket

The following is the simplest program that prints the command-line arguments:

<lang scheme>#lang racket (current-command-line-arguments)</lang>

You can also explicitly print each argument to standard output:

<lang scheme>#lang racket

(for ([arg (current-command-line-arguments)]) (displayln arg))</lang>

RapidQ

<lang rapidq>PRINT "This program is named "; Command$(0) FOR i=1 TO CommandCount

   PRINT "The argument "; i; " is "; Command$(i)

NEXT i</lang>

Raven

<lang raven>ARGS print

stack (6 items)

0 => "raven"
1 => "myprogram"
2 => "-c"
3 => "alpha beta"
4 => "-h"
5 => "gamma"</lang>

REALbasic

<lang vb>Function Run(args() as String) As Integer

 For each arg As String In args
   Stdout.WriteLine(arg)
 Next

End Function</lang> Output (given arguments: --foo !bar "bat bang"):

appName.exe
--foo
!bar
bat bang

REXX

The entire command line is passed by REXX to the program. <lang rexx>say 'command arguments:' say arg(1)</lang> Input:

myprogram -c "alpha beta" -b "gamma"

However, the the example shown, it's suggestted that (maybe) only options that start with a minus (-) are to be examined and assumed to be options. <lang rexx>parse arg aaa /*get the arguments. */

                                      /*another version:          */
                                      /*  aaa=arg(1)              */

say 'command arguments:' say aaa

opts= /*placeholder for options. */ data= /*placeholder for data. */

 do j=1 to words(aaa)
 x=word(aaa,j)
 if left(x,1)=='-' then opts=opts x   /*Option?  Then add to opts.*/
                   else data=data x   /*Must be data. Add to data.*/
 end

       /*the above process adds a leading blank to  OPTS and  DATA*/

opts=strip(opts,'L') /*strip leading blanks. */ data=strip(data,'l') /*strip leading blanks. */ say say 'options='opts say ' data='data</lang>

Notes to users of Microsoft Windows

Note that some REXX pass the command line as is, but Regina REXX lets the operating system parse it first (for instance Windows), and Windows will pass anything in inside double quotes (") to the program as is. Any other data not in double quotes is passed as is.

Output from Regina REXX under Windows with the invocation:

myprogram -c "alpha beta" -h "gamma"

command arguments:
-c alpha beta -h gamma

options=-c -h
   data=alpha beta gamma

Output from others REXXes under Windows with the invocation:

myprogram -c "alpha beta" -h "gamma"

command arguments:
-c "alpha beta" -h "gamma"

options=-c -h
   data="alpha beta" "gamma"

Notes to Unix users

The rexx programming language does not preserve command line parameters containing spaces. This renders it unsuitable for use for wrapperscript applications, where filenames containing spaces need to be preserved, because there is no way to differentiate between a space within a parameter, and a space used to separate parameters.

Scenario

If a script is called as follows:

ccwrapper "foo bar.c" "bar bar.c"

From the shell:

argv[0] = ccwrapper
argv[1] = foo bar.c
argv[2] = bar bar.c

It is a requirement of a wrapper that !argv[1] and !argv[2] are preserved when passed to the target application (a C compiler, in this example). Current implementations of rexx treat the command line arguments as one long argument:

arg() = 1
arg(1) = "foo bar.c bar bar.c"

The [parser] would separates the command line arguments by spaces. this results in !argv[1] and !argv[2] becoming split, so the target application would be called with different arguments:

argv[1] = foo
argv[2] = bar.c
argv[3] = bar
argv[4] = bar.c

This has a different meaning to the compiler, so the arguments forwarded from rexx are rendered useless.

Workaround

A workaround would be to create a wrapper around the rexx interpreter that encodes the commandline before calling rexx. The rexx application then decodes it. Some rexx interpreters, such as regina also provide a !-a switch as a workaround.

Ruby

Command line arguments are available in the constant Object::ARGV.

myprog: <lang ruby>#! /usr/bin/env ruby p ARGV</lang>

 myprog a -h b c
 => ["a","-h","b","c"]

Rust

<lang rust>use std::os;

fn main(){

   println!("{:?}", os::args());

}</lang> Run: <lang>./program -c "alpha beta" -h "gamma" ~[~"./args", ~"-c", ~"alpha beta", ~"-h", ~"gamma"]</lang>

Sather

<lang sather>class MAIN is

 main(args:ARRAY{STR}) is
   loop
     #OUT + args.elt! + "\n";
   end;
 end;

end;</lang>

As in C (and others), the first element is the command itself (exactly as it is written in the command line and after shell variable expansion); e.g.

$ /home/home/rosetta/sather/a.out arg1 arg2 arg3

prints

/home/home/rosetta/sather/a.out
arg1
arg2
arg3

Scala

Calling Scala from command line means invoking a method called main, defined on an object, whose type is (Array[String])Unit, meaning it receives an array of strings, and returns unit. That array contains the command line arguments.

<lang scala>object T {

 def main(args: Array[String]) {
   println("Received the following arguments": + args.mkString("", ", ", "."))
 }

}</lang>

When running a Scala script, where the whole body is executed, the arguments get stored in an array of strings called argv:

<lang scala>println("My arguments are: "+argv.mkString("", ", ", "."))</lang>

Scheme

<lang scheme> (define (main args)

 (for-each (lambda (arg) (display arg) (newline)) args))</lang>

Seed7

<lang seed7>$ include "seed7_05.s7i";

const proc: main is func

 local
   var integer: i is 0;
 begin
   writeln("This program is named " <& name(PROGRAM) <& ".");
   for i range 1 to length(argv(PROGRAM)) do
     writeln("The argument #" <& i <& " is " <& argv(PROGRAM)[i]);
   end for;
 end func;</lang>

Sidef

Command line arguments are available in the ARGV array. <lang ruby>say ARGV.dump;</lang>

Output:

% myprog -c "alpha beta" -h "gamma"
['-c', 'alpha beta', '-h', 'gamma']

Slate

<lang slate>StartupArguments do: [| :arg | inform: arg]</lang>

Smalltalk

Works with: GNU Smalltalk

<lang smalltalk>(1 to: Smalltalk getArgc) do: [ :i |

 (Smalltalk getArgv: i) displayNl

]</lang>

Works with: Smalltalk/X

<lang smalltalk>Smalltalk commandLineArguments printCR</lang>

Standard ML

<lang sml>print ("This program is named " ^ CommandLine.name () ^ ".\n"); val args = CommandLine.arguments (); Array.appi

 (fn (i, x) => print ("the argument #" ^ Int.toString (i+1) ^ " is " ^ x ^ "\n"))
 (Array.fromList args);</lang>

Tcl

The predefined global variable argc contains the number of arguments passed to the program after the script being executed, argv contains those arguments as a list. (The name of the script is in the argv0 global variable, and the name of the executable interpreter itself is returned by the command info nameofexecutable.) Retrieving the second argument might look something like this:

<lang tcl>if { $argc > 1 } {

   puts [lindex $argv 1]

}</lang>

(Tcl counts from zero, thus [lindex $list 1] retrieves the second item in the list)

Toka

Arguments are stored into an array. The first element in the array is the name of the program, the rest are the arguments in order. The number of arguments is provided by #args.

<lang toka>[ arglist array.get type cr ] is show-arg [ dup . char: = emit space ] is #= 1 #args [ i #= show-arg ] countedLoop</lang>

TXR

Command line arguments in TXR can be treated as the lines of a text stream, which is arranged using the directive @(next :args). Thus TXR's text parsing capabilities work over the argument list.

This @(next :args) should be written as the first line of the TXR program, because TXR otherwise interprets the first argument as the name of an input file to open.

<lang txr>@(next :args) @(collect) @arg @(end) @(output) My args are: {@(rep)@arg, @(last)@arg@(end)} @(end)</lang>

$ ./txr args.txr
My args are: {}
$ ./txr args.txr 1
My args are: {1}
$ ./txr args.txr 1 2 3
My args are: {1, 2, 3}

UNIX Shell

Bourne Shell

To retrieve the entire list of arguments: <lang bash>WHOLELIST="$@"</lang> To retrieve the second and fifth arguments: <lang bash>SECOND=$2 FIFTH=$5</lang>

Ursala

Command line arguments are accessible to an application through a data structure initialized by the run-time system. This example application does nothing but display the data structure on standard output. <lang Ursala>#import std

executable ('parameterized',)

clarg = <.file$[contents: --<>+ _option%LP]>+ ~command.options</lang> Here is a bash terminal session.

$ clarg -c alpha,beta -h gamma --foo=bar,baz
<
   option[
      keyword: 'c',
      parameters: <'alpha','beta'>],
   option[
      position: 1,
      keyword: 'h',
      parameters: <'gamma'>],
   option[
      position: 2,
      longform: true,
      keyword: 'foo',
      parameters: <'bar','baz'>]>

V

The arguments to the program are stored in the stack,

args.v <lang v>$stack puts

./args.v a b c =[args.v a b c]</lang>

Visual Basic

Like Qbasic, Visual Basic returns all of the args in the built-in variable Command$: <lang vb>Sub Main

   MsgBox Command$

End Sub</lang>

Visual Basic .NET

This syntax will tokenize the command line arguments. Tokens are normally delimited by spaces, but spaces can be part of a token if surrounded by quotes.

<lang vbnet>Sub Main(ByVal args As String())

   For Each token In args
       Console.WriteLine(token)
   Next

End Sub</lang>

zkl

File myprogram.zkl: <lang zkl>System.argv.println(); vm.arglist.println();</lang> zkl myprogram -c "alpha beta" -h "gamma"

Output:

L("/home/craigd/Projects/ZKL/Bin/zkl","myprogram","-c","alpha beta","-h","gamma")
L("-c","alpha beta","-h","gamma")

Revision as of 22:27, 11 May 2014

Alternative version using Matreshka

Icon and Unicon

Using the Arg module

Raw arguments

Preprocessed arguments

Reading all parameters

Reading specific parameters

Notes to users of Microsoft Windows

Notes to Unix users

Scenario

Workaround