How to Create Custom Command in AutoCAD Quickly

To create a custom command in AutoCAD, use the CUI (Customize User Interface) editor to define a new command and assign it a name and macro. Alternatively, write an AutoLISP script and load it to run custom commands with specific actions.

Syntax

Creating a custom command in AutoCAD involves two main methods:

• CUI Editor: Define a command name, description, and macro that runs AutoCAD commands.
• AutoLISP: Write a function with (defun) that performs actions, then load it and call the function as a command.

In CUI, the macro syntax uses ^C^C to cancel current commands and then runs commands with ; to separate them.

lisp

;; AutoLISP function syntax
(defun c:MyCommand ()
  (command "LINE" (getpoint "Start point: ") (getpoint "End point: ") "")
  (princ)
)

Example

This example shows how to create a simple custom command named MyLine using AutoLISP that draws a line between two points.

After loading the script, typing MyLine in the command line will prompt for start and end points and draw the line.

lisp

(defun c:MyLine ()
  (command "LINE" (getpoint "Start point: ") (getpoint "End point: ") "")
  (princ)
)

; To load this, save as MyLine.lsp and use APPLOAD command in AutoCAD.

Output

User is prompted: Start point: (user clicks)
User is prompted: End point: (user clicks)
A line is drawn between the two points.

Common Pitfalls

• Forgetting to prefix AutoLISP commands with c: in the function name means the command won't be recognized in AutoCAD.
• Not loading the LISP file before running the command causes "undefined command" errors.
• In CUI macros, missing ^C^C at the start can cause commands to run unexpectedly if another command is active.
• Using incorrect syntax in macros or LISP functions leads to errors or no action.

lisp

(defun MyLine () ; Missing c: prefix
  (command "LINE" (getpoint "Start point: ") (getpoint "End point: ") "")
  (princ)
)

; Correct way:
(defun c:MyLine ()
  (command "LINE" (getpoint "Start point: ") (getpoint "End point: ") "")
  (princ)
)

Quick Reference

Step	Description
Open CUI Editor	Type CUI in command line and press Enter
Create New Command	Right-click Commands > New Command
Name Command	Give a unique name and description
Set Macro	Enter macro like ^C^C_LINE; to run commands
Add to Ribbon/Menu	Drag command to desired location
Save and Test	Save changes and run command by name
AutoLISP	Write (defun c:CmdName () ...), load with APPLOAD

Key Takeaways

Use the CUI editor to create commands with macros for simple automation.

Write AutoLISP functions with the c: prefix to define custom commands.

Always load your AutoLISP scripts before running custom commands.

Start macros with ^C^C to cancel any active commands safely.

Test your commands carefully to avoid syntax errors and unexpected behavior.