The following table provides a summary of the AutoLISP Express Tools system functions.
| System functions | Platforms | |||||
|---|---|---|---|---|---|---|
| Windows | Mac OS | Web | ||||
| Function | Description | AutoCAD | AutoCAD LT | AutoCAD | AutoCAD LT | AutoCAD | 
| Makes a noise | ✓ | -- | -- | -- | -- | |
| Runs a command in a shell and waits for the shell to complete execution before returning | ✓ | -- | -- | -- | -- | |
| Forces AutoCAD's application window to be the topmost and receive focus | ✓ | -- | -- | -- | -- | |
| Checks the state of a virtual key | ✓ | -- | -- | -- | -- | |
| Reports the last error | ✓ | -- | -- | -- | -- | |
| Returns the current process identifier | ✓ | -- | -- | -- | -- | |
| Delay to allow other processes to run | ✓ | -- | -- | -- | -- | |
| Executes an external program | ✓ | -- | -- | -- | -- | |
| Terminates the given process | ✓ | -- | -- | -- | -- | |
| Waits for a process to complete | ✓ | -- | -- | -- | -- | |