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  Arguments
 
    pathname        String expression representing name of the child
                    process to be executed
 
    command_line    String expression representing the command line for
                    executing the child process
 
  Description
 
    The Exec procedure loads and runs a child process. It suspends the
    parent process that called Exec. The arguments specify the program
    to be run and the command line to pass to the program.
 
    The pathname argument passes the name of the program to be executed,
    which can be a base name with an extension or a fully qualified DOS
    path name including drive letter and subdirectories. Exec assumes
    the current directory if no directory is specified. The argument is
    of type PathStr, defined in the Dos unit.
 
    The command_line argument passes commands or options to pass to the
    child process. These commands are the arguments that would be given
    after the name of the program on the DOS command line. If the
    program needs no arguments, pass an empty string. The argument is
    of type ComStr, defined in the Dos unit.
 
    Exec does not allocate memory for the child process. To ensure
    enough memory, use the {$M} directive at the beginning of the
    parent program. To leave room for the child process to load and
    run, set the stack and heap to the minimum possible settings.
 
    Exec does not save any interrupt handlers for the parent. To
    protect existing vectors from interference by the child process,
    call the SwapVectors procedure before and after calling Exec.
 
    Use the DosExitCode function to obtain the exit code returned by
    the child process.
 
    To execute a DOS command as the child process, specify COMMAND.COM
    as the pathname argument. Specify the desired DOS command as the
    command_line argument, preceded by a /c switch, which is not
    case-sensitive. The /c switch tells DOS that the COMMAND.COM being
    run is another copy. For example, to see a listing of executable
    files in the current directory:
 
       Exec( 'COMMAND.COM', '/C DIR *.EXE' );
 
    Exec reports error conditions in DosError. Possible error values
    are 2, 8, 10, and 11:
 
      Value    Error
      ═════    ═══════════════════
 
      2        File not found
      8        Not enough memory
      10       Invalid environment
      11       Invalid format