U

U takes back the last change you made to the drawing. Run it again to go one more step back. If you undo too far, REDO brings the step back.

How it works

Type U and press Enter. Musa CAD prints Undo and the drawing goes back one step. There is nothing to answer. Typing UNDO does exactly the same.

Command line

Command: U
Undo
Command: U
Undo
Command: REDO
Redo

Here the two U’s take back the last two changes, and REDO puts back the one the second U took away.

You can also undo with:

• Ctrl+Z,
• the Undo button on the Quick Access Toolbar, the small row of buttons by the ribbon,
• Undo on the menu you get by right-clicking in the drawing.

Each of these prints Undo too. Redo has a Redo button next to Undo, and a Redo item on the same right-click menu. Its key follows your system: Ctrl+Y on Windows, Ctrl+Shift+Z on Linux. Ctrl+Y does not redo on Linux yet; that is issue #85.

What one step is

One step is everything one command changed. If you drew four segments with one LINE, one U removes all four. If you moved ten objects with one MOVE, one U puts all ten back.

A few commands make each action its own step, so U goes back one action at a time. For example:

• each line of TEXT,
• each click or drag in TRIM,
• each option you use in PEDIT,
• each click or window in MATCHPROP,
• each edit in TEXTEDIT.

REDO

REDO brings back the last step you undid. It also takes no answer and prints Redo. To bring back several steps at once, use MREDO, which asks Enter number of actions or [All/Last]:.

Redo only works straight after undoing. As soon as you make a new change, the steps you undid can no longer be brought back.

Good to know

• There is no fixed limit on how many steps you can undo. The history starts when you open or start the drawing.
• Each open drawing has its own history. Undo in one tab does not touch another tab.
• When nothing is left to undo, U still prints Undo, and nothing changes.
• U undoes changes to objects. Zooming and panning are not steps, so U does not change the view.
• Many commands have an Undo option of their own, such as LINE, TRIM and PEDIT. Typing U at one of their prompts uses that option, not this command.
• To bring back only the objects you last erased, use OOPS.

Compared with AutoCAD

U works the way AutoCAD users expect: one step back each time. In Musa CAD, UNDO is another name for U. It takes back one step and asks nothing.

Next

• Bring back what you undid with REDO or MREDO.
• Bring back erased objects with OOPS.
• Learn the basics of changing a drawing in Modifying.