The Undo command can (usually) be used to undo the most recent action. Most actions can be undone - for example, if you rename a group of files incorrectly with a wildcard, you can undo the rename fairly easily. File deletes, however, can not be undone unless the delete was done to the recycle bin. You can find the Undo command in the Edit menu in a Lister (or press Ctrl+Z).

Opus maintains a history of undoable functions. From the Undo List sub-menu, you can see the ten most recent actions, and undo any of them by selecting it from the list. Selecting the More… command from that sub-menu displays the Utility Panel, showing the Undo Log page. This page displays a full list of undoable actions, and you can undo one, many or all actions from this page at the click of a button.

While the undo log only shows the most recent undoable actions in the current session, the file log maintains a persistent log of all file operations (undoable or not). You can access the File Log from the Utility Panel, or select the command directly from the Help menu.

By default the file log records the last 1000 file operations. You can see what sort of action occurred, the file involved, when it happened, and in the case of a copy or move, the destination folder.

The file log can be extremely useful at times - if you've ever found that a file you knew was there has mysteriously disappeared, you can often find out what happened to it through the log. You can use the filter field to search for a file by name or path.

The Save button at the top of the log lets you export the log as a text file - useful if it's quite large and you want to search it in a text editor. You can configure the maximum size of the log, and control which operations are recorded, from the File Operations / Logging page in Preferences.