The AUTOPUBLISH command is a way to quickly publish to a DWF, DWFx, or PDF file. To specify the settings that this command uses, choose Application Button > Options and click the Plot and Publish tab. In the Auto Publish section, click the Automatic Publish Settings button. There you can specify settings similar to those you set by clicking the Publish Options button in the Publish dialog box. I cover the PUBLISH command here.
The AUTODWFPUBLISH system variable turns the AutoPublish feature on and off. When you turn this system variable on (set its value to 1), AutoCAD executes the AUTOPUBLISH command every time you save or close the a drawing. You can also turn this system variable on in the Auto Publish section of the Plot and Publish tab of the Options dialog box by checking the Automatic Publish check box. Turn on AUTODWFPUBLISH if you always need to keep DWF, DWFx, or PDF files synchronized with your drawings.