2011

Table Of Contents
return_code An optional bitcoded parameter. You can add these integer
values together in any combination to achieve the result you want. For
example, if values 1 and 2 are required, you use 3 as the return code. The values
are defined as follows (codes 0 and 4 are meaningless in a windowed
environment and are therefore not included):
1 Loads a DXB file. AutoCAD loads the DXB file named $cmd.dxb into the
drawing after the command is terminated. After the DXB file is loaded, the
$cmd.dxb file is deleted. This action produces the same result as the DXBIN
command.
2 Constructs a block definition from a DXB file. AutoCAD creates a block
definition from the DXB file named $cmd.dxb. The response to the prompt
field is used as the block name. This name must be a valid block name that
does not currently exist in the drawing; therefore, this mode cannot redefine
a previously defined block. After AutoCAD loads the DXB file, the $cmd.dxb
file is deleted. The default name for the INSERT command is set to the newly
defined block.
The file can also contain comment lines preceded by a semicolon (;).
Windows System Commands
The start and cmd Windows system commands are very useful when defining
external commands. If you specify an executable string that does not use the
start or cmd command, AutoCAD is unavailable until that window is closed.
The start command starts a separate window and runs a specified program or
command. If start is used without any parameters, it opens a new command
prompt window. The start command has many command line switches that
affect the display of the new window. To launch a Windows application, use
start without any switches. The start command is also very useful for starting
a document that is associated with an application. For example, you can use
start to directly open a document created with a word processor or an HTML
file.
The cmd command opens a command prompt window that acts as a shell of
AutoCAD. This window must be closed before control returns to the AutoCAD
command prompt. Two command line switches, /c and /k, are useful for
external commands. The /c switch carries out the specified command and
then stops (the window closes). The /k switch carries out the specified
command and then continues (the window remains open). When using the
/k switch, you must close the command window (with the exit command).
In general, use start to start a new window or application that is to be a separate
process from AutoCAD. Use cmd to run a batch file or command script that
does not create a separate window, or to create a window that must be closed
22 | Chapter 1 Basic Customization