10 PRINT "HELLO WORLD"
20 END

  program Hello(input, output)
    begin
      writeln('Hello World')
    end.

  (defun hello
    (print
      (cons 'Hello (list 'World))))

  #include 
  void main(void)
  {
    char *message[] = {"Hello ", "World"};
    int i;
 
    for(i = 0; i < 2; ++i)
      printf("%s", message[i]);
    printf("\n");
  }

  #include 
  #include 
 
  class string
  {
  private:
    int size;
    char *ptr;
 
  string() : size(0), ptr(new char[1]) { ptr[0] = 0; }
 
    string(const string &s) : size(s.size)
    {
      ptr = new char[size + 1];
      strcpy(ptr, s.ptr);
    }
 
    ~string()
    {
      delete [] ptr;
    }
 
    friend ostream &operator <<(ostream &, const string &);
    string &operator=(const char *);
  };
 
  ostream &operator<<(ostream &stream, const string &s)
  {
    return(stream << s.ptr);
  }
 
  string &string::operator=(const char *chrs)
  {
    if (this != &chrs)
    {
      delete [] ptr;
     size = strlen(chrs);
      ptr = new char[size + 1];
      strcpy(ptr, chrs);
    }
    return(*this);
  }
 
  int main()
  {
    string str;
 
    str = "Hello World";
    cout << str << endl;
 
    return(0);
  }

  #!/usr/local/bin/perl
  $msg="Hello, world.\n";
  if ($#ARGV >= 0) {
    while(defined($arg=shift(@ARGV))) {
      $outfilename = $arg;
      open(FILE, ">" . $outfilename) || die "Can't write $arg: $!\n";
      print (FILE $msg);
      close(FILE) || die "Can't close $arg: $!\n";
    }
  } else {
    print ($msg);
  }
  1;

  % echo "Hello, world."

  10 PRINT "HELLO WORLD"
  20 END

  mail -s "Hello, world." bob@b12
  Bob, could you please write me a program that prints "Hello, world."?
  I need it by tomorrow.
  ^D

  % zmail jim
  I need a "Hello, world." program by this afternoon.

  % letter
  letter: Command not found.
  % mail
  To: ^X ^F ^C
  % help mail
  help: Command not found.
  % damn!
  !: Event unrecognized
  % logout