Category Archives: Folder Actions

make your own Trash Watcher utility

Trash watcher 2

So twice in the last couple of weeks, I’ve found that something funny has been going on with Xcode, source control and Dropbox. The weird behaviour is that both times a whole load of my Xcode projects got moved to the Trash without my knowledge or permission. Fortunately, I noticed in both cases, and while I haven’t got to the bottom of the problem yet, I thought the first thing I’d better do is a bit of defensive scripting!

With that in mind, I created this little Trash Watcher utility to warn me anytime something is moved to the Trash. It’s quick and easy to make, and you can customise it to do various other things apart from give a warning if you like (for example, you could make it delete files of a certain kind, size or date automatically).

Start by opening the AppleScript editor (or Script Editor on 10.10), and paste the following lines into it:


on adding folder items to this_folder after receiving added_items

set listOfFiles to {}
repeat with i from 1 to the count of added_items
set a_file to item i of added_items as text
set stripTrashPath to offset of "Trash" in a_file
set a_file to text (stripTrashPath + 6) thru -1 of a_file
set a_file to a_file & "
"
set end of listOfFiles to a_file
end repeat

display dialog "The following items were moved to Trash: " & return & return & listOfFiles buttons {"OK", "View"} default button "View" cancel button {"OK"} with title "Trash Alert" with icon 0
set btn to button returned of the result
if (btn = "View") then
tell application "Finder" to open the trash
end if
end adding folder items to

 

Here’s what the code does. The first and last lines define a Folder actions handler, where the variables ‘this_folder’ and ‘added_items’ will be replaced by the name of the folder you attach this script too (we’ll do that in a minute), namely the Trash folder, and the items that have been moved to the Trash.

The next line, declares an empty list, so that we can populate it later with just the names of the items, rather than their full path adddress.

Then comes the repeat block. This first determines how many items there are to be added and then iterates over them, applying the five ‘set’ commands on each file. Those five commands are all doing one thing: stripping the path from the item name down to just the item name itself so that we can display it nicely in the display dialog command that follows.

Note that the display dialog command adds a couple of buttons, and collects the result as to which button you pressed. Notice that “OK” (typically an action button) is used to dismiss or cancel the dialog. “View” opens the Trash folder in the event that you want to check or remove the items that have been added.

With the Script editor active, make sure your script compiles by pressing ‘Command-K’, but don’t try to run it yet. We need to attach save the script in the right place first, and then attach it to the Trash folder.

With Script editor still active, press ‘Command-S’ to bring up the ‘Save’ dialog box. Give it a descriptive name like ‘TrashWatcher.scpt’ or similar. Do not click ‘Save’, but instead press, ‘Command-Shif-G’ on your keyboard and enter this location into the box that pops up:

~/Library

and click ‘Go’. In the resulting window, scroll down to the Scripts folder and look inside it. If there is already a folder called ‘Folder Action Scripts’ then save the script in there. If not, click ‘New Folder’ in the bottom left of the window, and create a ‘Folder Action Scripts’ folder (be sure to get the name exactly right).

With the script saved in ~/Library/Scripts/Folder Action Scripts/, right click on any folder in a Finder window and choose ‘Services > Folder Action Setup’ from the contextual menu.

Folder Actions Setup

This will open a new dialog box with a list of scripts to choose from. Choose the TrashWatcher.scpt (or whatever you happened to call it) and click “Attach”. In the remaining panel, make sure the Trash folder is selected and no other.

That’s pretty much it; your TrashWatcher folder is set up, so move something to the Trash and make sure it fires. Everything OK? Hmm, maybe, but we need a few refinements. For one thing, every now and again OS X will move the .DS_Store files to the Trash, and we don’t want to know about these. Also, it would be good if the file name actually indicated whether it was file or a folder that was being moved. In fact, it does so already (Folders are indicated by a colon), but it would perhaps be clearer and more orthodox if folders were followed by a forward slash, as they are usually indicated that way in path names. To achieve both of these, refine the script above to look as follows, remembering to compile, save and test it (by moving something to the Trash, not from running in the Script Editor).


final script

Finally, with a bit of imagination and experimentation, you could add various other conditions to this script. For example, you could have it immediately delete files that are of a certain size or certain kind as soon as they are placed in the trash (tip: you’ll need to use Finder’s “empty the Trash” command after testing each file for whatever criterion you want to use). I’ll leave those as exercises for the reader, but feel free to post your scripts in the comments if you’re particularly pleased with some variation you’ve come up with!

Happy Scripting!

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