Today's featured command came in courtesy of Samir Abdelmawla who suggested I talk about "the other SAVE command":
"The command SAVE as typed on the command line offers a different option than what you see on the File -> Save, Ctrl + S or the Save icon on the Quick Access Toolbar, as all of these invoke the QSAVE command. The SAVE command is similar in a sense to SAVEAS command the only difference is that it creates another drawing file without changing it as the current drawing. So if you are working on design options and want to keep a snapshot and continue on the same drawing, use the SAVE command."
Essentially, there are three options for saving: QSAVE, SAVE, and SAVEAS.
QSAVE is the one most people use all the time because, as Samir points out, it is the one associated with the most-used menu and toolbar options for saving. QSAVE just does a quick save (hence the name) of the current drawing. No fuss, no muss, no options. If the drawing is unsaved, it will prompt for a name but nothing beyond that.
With SAVE you have the option of changing the drawing name (or path) when saving the current drawing. This allows you to create an entirely new drawing file from the current drawing, but without it becoming the current drawing.
I'm working in TOM.DWG and I issue the SAVE command. I change the name to TOM2.DWG and that creates a new drawing on disk named TOM2.DWG, however my current drawing is still TOM.DWG (and is not considered saved). Again, as Samir has noted, this is nice for creating interim "snapshots" of drawings without the saved drawing becoming the current drawing.
Note: Closing the original drawing immediately after a SAVE to another name or location will not prompt to save any unchanged work in the original drawing. Although those changes were saved to the new drawing file it also reset DBMOD for the current drawing. AutoCAD no longer sees the current drawing as having any unsaved changes so it will close the drawing without prompting you to save. Important safety tip.
The SAVEAS command is very much like SAVE except that if you change the drawing name, it creates a new drawing and makes that drawing current.
I'm working in TOM.DWG and I issue the SAVEAS command. I change the name to TOM2.DWG and that creates a new drawing on disk named TOM2.DWG and my current drawing is now TOM2.DWG. If there were changes to TOM.DWG between my last save and the SAVEAS, they are not included in TOM.DWG (but are in TOM2.DWG).
For both SAVE and SAVEAS, if you use the same path and name as what the current drawing already has, you will be prompted to overwrite. In those cases it's like doing a QSAVE but with an extra prompt to deal with.