TweetFollow Us on Twitter

Becoming More Efficient through Folder Watching

Volume Number: 20 (2004)
Issue Number: 7
Column Tag: Programming

AppleScript Essentials

by Benjamin S. Waldie

Becoming More Efficient through Folder Watching

For the past several months, we have explored various aspects of AppleScripting in Mac OS X. We have discussed some basic Finder scripting, adding repeat loops and if/then statements to our scripts, and more. This month, we will explore a topic of frequent interest to those who want to automate various aspects of their workflow - folder watching.

Folder Watching

Folder watching is a common automation technique that can be used to make virtually any workflow more efficient. By configuring AppleScripts to monitor folders for new items to arrive, users are able to set up watched folders to automatically process incoming items.

Folder watching can be extremely useful in a variety of situations. For example, let's say that a user in your office copies files into a drop box on your computer at various times throughout the day. Whenever these files arrive, they need to be processed. Since you have other work to do too, you may not be able to monitor the drop box for new files on a regular basis. To assist with the process, you could create an AppleScript that monitors this drop box for you, and then notifies you whenever a new item is detected. Once notified, you could manually process the detected files. Or, you could write additional AppleScript code to process the files for you, completely removing all aspects of manual processing.

In some cases, you need to configure a large number of watched folders for multiple workflows. A common technique for dealing with this type of situation is to set up an AppleScript server. In other words, any dedicated Mac whose primary purpose is to watch these folders for new items, and then process the detected items. By integrating a dedicated folder watching machine into a workflow, users are able to hand off their files for processing, freeing them to work on other less time consuming and repetitive tasks.

In this article, we will discuss some basic ways to create a folder watching script. Then, you can expand these techniques in order to create more complex automated systems.

Idle Folder Watching

One method for writing a script that will watch a folder is to create an AppleScript that has been saved as a stay open application and makes use of AppleScript's idle handler. A stay open application is a script that, when launched, will remain open until manually quit by the user, or told to quit by the script itself, or by another script.

on idle
   -- Add code here to watch the folder
end idle

Handlers are an important, yet fairly complex topic. I will explain handlers in detail in a future article. In the meantime, this tech-note provides a very brief overview of a handler.

A handler is a group of AppleScript statements that may be executed with a single command. There are two types of handlers in AppleScript - subroutine handlers and command handlers. Subroutine handlers are groups of statements, which are defined by the developer, and called throughout a script, or from another script. A command handler is a group of statements that is triggered by an event, such as when a script is run, opened, quit, or idle. The idle handler is considered to be a command handler.

An idle handler will always begin with an on idle line and end with an end idle line. Any AppleScript code in-between these two lines will trigger whenever the script becomes idle. In a stay open script, by default, the idle handler will trigger every 30 seconds. However, you may optionally customize this delay period by adding a line to the end of the idle handler that returns a number of seconds to delay before becoming idle again. In the code below, the script would wait 1 second between executions of the idle handler.

on idle
   -- Add code here to watch the folder
   return 1 -- The number of seconds the script should delay before being idle again
end idle

Once you have a shell for your idle handler, it is time to begin adding some folder watching code. The following example represents a very basic folder watching script. In this example, the script will monitor a user specified folder for items. Whenever items are detected in the folder, they will be moved immediately to the desktop, and the user will be notified that items were detected and moved. The idle handler in this example will trigger once every second. Of course, this example could be expanded to have much greater functionality. For example, you could write code to process only new images that are placed in the folder. The script could be written to open those images in Photoshop, perform various image manipulations, and then save the images into an output folder.

global theWatchedFolder
set theWatchedFolder to choose folder
on idle
   tell application "Finder"
      set theDetectedItems to every item of theWatchedFolder
      repeat with aDetectedItem in theDetectedItems
         move aDetectedItem to the desktop
      end repeat
   end tell
   if theDetectedItems <> {} then
      activate
      display dialog "New items were detected and moved to your desktop."
   end if
   return 1
end idle

In the example above, the first line of code indicates that the variable theWatchedFolder will be a global variable. In other words, once assigned, this variable will be available to all areas of the script, at all times. The second line of code prompts the user to choose a folder, and assigns a reference to the chosen folder to the global variable theWatchedFolder. Because these first two lines of code do not fall within the idle handler, they will only be executed when the script is initially launched.

The code within the idle handler executes after the initial code has finished running. Once executed, it determines whether any items exist in the chosen folder. If items are detected in the folder, the script moves them to the desktop, and then notifies the user that items were detected and moved.

By moving items out of the watched folder, the script ensures that the same items are not detected and reprocessed during the next idle period. If necessary, the script could instead be expanded to keep track of the items in the folder, and only process when new items are added. However, this would require quite a bit more development. Therefore, it is common practice to move files from a watched folder into an output folder once processing is complete.

As previously mentioned, idle handlers are used in scripts that have been saved as stay open applications. Therefore, in order to test the code above, you will need to save the script as a stay open application. To save a script as a stay open application, save the script as an application and select the Stay Open checkbox in Script Editor's save dialog, as shown in Figure 1.


Figure 1. Stay Open Application Save Option

You are now ready to test your script. Launch it from the Finder and select a folder. Next, try moving or copying items into the selected folder, and they should be moved to the desktop.

Folder Actions

Another method of creating a folder watching script is to make use of Mac OS X's built-in Folder Actions support. Folder Actions offer a more robust way to configure watched folders, with less coding needed.

What is a Folder Action?

A Folder Action is a specially written AppleScript, which may be attached to a folder. Folder Actions may be configured to trigger when specific types of action are taken on the folder they are attached to. Folder Actions may be written to trigger whenever:

  • A folder is opened

  • A folder's opened window is moved

  • A folder's opened window is closed

  • Items are added or removed from a folder

Information about Folder Actions, including sample code for configuring each type of Folder Action can be found on Apple Computer's web site at <http://www.apple.com/applescript/folderactions>.

Creating a Folder Action

To create a Folder Action, much like the idle handler, you add a specific handler into your script, indicating the type of action that will trigger the script. Different types of Folder Action handlers exist, and the one that you will need to use will depend on the type of action that you want to trigger your AppleScript code. A list of available Folder Action handlers can be found in the Folder Actions suite in the Standard Additions scripting addition that is installed with Mac OS X.


Figure 2. Folder Actions in the Standard Additions Scripting Addition

As you can see in Figure 2, there are several different types of Folder Action handlers that you may include in your script. Since this article specifically talks about folder watching, we will only discuss the adding folder items to Folder Action handler, which is used to process items added to a folder. However, I encourage you to try out the other types of Folder Action handlers as well.

To create a Folder Action that will process items that are moved or copied into an attached folder, add the adding folder items to Folder Action handler into your script.

on adding folder items to theWatchedFolder after receiving theDetectedItems

-- Add processing code here

end adding folder items to

In the example above, the first line of the handler contains two labeled parameters, theWatchedFolder and theDetectedItems. These parameters will pass dynamically assigned values to the script whenever the script is triggered. The parameter theWatchedFolder will contain an AppleScript alias reference to the folder that the script is attached to. The parameter theDetectedItems will contain a list of AppleScript alias references to the items that were added to the attached folder.

The on adding folder items to handler will only trigger when new items are added to the attached folder, providing to the script a list of only the newly added items. Therefore, unlike the script we created using the idle handler, we could choose to process the newly detected items, without moving them out of the watched folder.

Since, when the script is triggered, it will already have a list of newly added items, there is no need to write code to determine which items were detected. Instead, we only need to add code to process the detected items. The following example code, just like our idle handler, will move newly added items to the desktop, and then notify the user.

on adding folder items to theWatchedFolder after receiving theDetectedItems
   tell application "Finder"
      move theDetectedItems to the desktop
   end tell
   activate
   display dialog "New items were detected and moved to your desktop."
end adding folder items to

Once you have written your Folder Action script, you need to save it as a compiled script.


Figure 3. Saving a Folder Action Script

Place the saved Folder Action script into the Library > Scripts > Folder Action Scripts folder on your computer. Next, you need to actually attach the script to the folder you want to watch.

Configuring a Folder Action

To attach a Folder Action script to a folder, launch the Folder Actions Setup application, which is located in the Applications > AppleScript folder in Mac OS X 10.3 and higher. Once launched, verify that the Enable Folder Actions checkbox is selected. You must enable Folder Actions in order for them to function.


Figure 4. Enabling Folder Actions

Click the + button under the Folders with Actions field, and you will be prompted to select a folder. Make your selection, and click the Open button in the folder selection dialog window. You will then be prompted to select a Folder Action script to attach to the specified folder. Select the desired Folder Action script, and click the Attach button.


Figure 5. Selecting a Folder Action Script

As the Folder Actions Setup application interface will indicate, your Folder Action script is now attached to the folder that you specified.


Figure 6. A Configured Folder Action

Now that configuration is complete, quit the Folder Actions Setup application, and test your Folder Action script by copying or moving items into the attached folder. If everything has been properly configured, then your Folder Action script should process the items placed in the attached folder.

Please note that it is also possible to configure Folder Actions through the contextual menu in the Finder. To display the contextual menu, control click on the desired folder in the Finder.


Figure 7. Folder Action Contextual Menus

In Closing

While the idle handler method of folder watching can be useful at times, Folder Actions offer a very useful way to configure watched folders without a lot of extra coding. I strongly urge you to begin exploring Folder Actions in more detail. As you begin using them, you will wonder how you ever got along without them.

Until next time, keep scripting!


Benjamin Waldie is president of Automated Workflows, LLC, a firm specializing in AppleScript and workflow automation consulting. In addition to his role as a consultant, Benjamin is an evangelist of AppleScript, and can frequently be seen presenting at Macintosh User Groups, Seybold Seminars, and MacWorld. For additional information about Benjamin, please visit http://www.automatedworkflows.com, or email Benjamin at applescriptguru@mac.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

OnyX 3.2.4 - Maintenance and optimizatio...
OnyX is a multifunction utility that you can use to verify the startup disk and the structure of its system files, to run miscellaneous maintenance and cleaning tasks, to configure parameters in the... Read more
Opera 43.0.2442.991 - High-performance W...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more
VueScan 9.5.71 - Scanner software with a...
VueScan is a scanning program that works with most high-quality flatbed and film scanners to produce scans that have excellent color fidelity and color balance. VueScan is easy to use, and has... Read more
SpamSieve 2.9.28 - Robust spam filter fo...
SpamSieve is a robust spam filter for major email clients that uses powerful Bayesian spam filtering. SpamSieve understands what your spam looks like in order to block it all, but also learns what... Read more
GarageSale 7.0.7 - Create outstanding eB...
GarageSale is a slick, full-featured client application for the eBay online auction system. Create and manage your auctions with ease. With GarageSale, you can create, edit, track, and manage... Read more
Thunderbird 45.7.1 - Email client from M...
As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements... Read more
GarageSale 7.0.7 - Create outstanding eB...
GarageSale is a slick, full-featured client application for the eBay online auction system. Create and manage your auctions with ease. With GarageSale, you can create, edit, track, and manage... Read more
SpamSieve 2.9.28 - Robust spam filter fo...
SpamSieve is a robust spam filter for major email clients that uses powerful Bayesian spam filtering. SpamSieve understands what your spam looks like in order to block it all, but also learns what... Read more
Thunderbird 45.7.1 - Email client from M...
As of July 2012, Thunderbird has transitioned to a new governance model, with new features being developed by the broader free software and open source community, and security fixes and improvements... Read more
Opera 43.0.2442.991 - High-performance W...
Opera is a fast and secure browser trusted by millions of users. With the intuitive interface, Speed Dial and visual bookmarks for organizing favorite sites, news feature with fresh, relevant content... Read more

Last week on Pocket Gamer
If you’re wondering what’s going on in the wider world of portable gaming, our sister site PocketGamer has you covered. Each week we like to check in on the PG team and see what they’ve been preoccupied with. From the latest on the Nintendo Switch... | Read more »
Mudd Masher arrives this week
Atooi Games, the minds behind Totes the Goat and Mutant Mudds, have a new game in the works -- Mudd Masher. The game, a hybrid of the independent studio's first two titles, is expected to launch this week on March 2. [Read more] | Read more »
The best sales on the App Store this wee...
The App Store has quite an exciting lineup of discount games this week that range across a variety of genres. It's a great opportunity to catch up on some of the premium games you may have been holding off on -- and some you can even grab for free... | Read more »
The best new games we played this week
Ah, here we are again at the close of another busy week. Don't rest too easy, though. We had a lot of great new releases in mobile games this week, and now you're going to have to spend all weekend playing them. That shouldn't be too much of a... | Read more »
Rollercoaster Tycoon Touch Guide: How to...
| Read more »
Rabbids Crazy Rush Guide: How to unlock...
The Rabbids are back in a new endless running adventure, Rabbids Crazy Rush. It's more ridiculous cartoon craziness as you help the little furballs gather enough fuel (soda) to get to the moon. Sure, it's a silly idea, but everyone has dreams --... | Read more »
Tavern Guardians (Games)
Tavern Guardians 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Tavern Guardians is a Hack-and-Slash action game played in the style of a match-three. You can experience high pace action... | Read more »
Slay your way to glory in idle RPG Endle...
It’s a golden age for idle games on the mobile market, and those addictive little clickers have a new best friend. South Korean developer Ekkorr released Endless Frontier last year, and players have been idling away the hours in the company of its... | Read more »
Tiny Striker: World Football Guide - How...
| Read more »
Good news everyone! Futurama: Worlds of...
Futurama is finding a new home on mobile in TinyCo and Fox Interactive's new game, Futurama: Worlds of Tomorrow. They're really doing it up, bringing on board Futurama creator Matt Groening along with the original cast and writers. TinyCo wants... | Read more »

Price Scanner via MacPrices.net

13-inch 2.7GHz Retina MacBook Pro on sale for...
B&H Photo has the 2015 13″ 2.7GHz/128GB Retina Apple MacBook Pro on sale for $150 off MSRP. Shipping is free, and B&H charges NY tax only: - 13″ 2.7GHz/128GB Retina MacBook Pro (MF839LL/A): $... Read more
13-inch 1.6GHz/256GB MacBook Air on sale for...
Newegg has the 13″ 1.6GHz/256GB MacBook Air (MMGG2LL/A) on sale for $1029.99 including free shipping. Their price is $170 off MSRP, and it’s the lowest price available for this model. Choose Newegg... Read more
Apple refurbished Apple TVs available for up...
Apple has Certified Refurbished 32GB and 64GB Apple TVs available for up to $30 off the cost of new models. Apple’s standard one-year warranty is included with each model, and shipping is free: -... Read more
27-inch 3.3GHz 5K iMac on sale for $2099, sav...
B&H Photo has the 27″ 3.3GHz 5K Apple iMac on sale for $2099.99 including free shipping plus NY sales tax only. Their price is $200 off MSRP. Amazon also has the 27″ 3.3GHz 5K iMac on sale for $... Read more
21-inch iMacs on sale for up to $111 off MSRP
B&H Photo has select 21″ Apple iMacs on sale for up to $110 off MSRP, each including free shipping plus NY sales tax only: - 21″ 2.8GHz iMac: $1189 $110 off MSRP - 21″ 1.6GHz iMac: $999 $100 off... Read more
12-inch 1.2GHz Retina MacBooks on sale for $2...
Newegg has the 12″ 1.2GHz Space Gray Retina MacBook (sku MLH82LL/A) on sale for $1349.99 including free shipping. Their price is $250 off MSRP, and it’s the lowest price available for this model.... Read more
13-inch MacBook Airs on sale for $100 off MSR...
B&H Photo has 13″ MacBook Airs on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 1.6GHz/128GB MacBook Air (MMGF2LL/A): $899 $100 off MSRP - 13″ 1.6GHz/... Read more
9-inch 32GB Silver iPad Pro on sale for $549,...
B&H Photo has the 9.7″ 32GB Silver Apple iPad Pro on sale for $549 for a limited time. Shipping is free, and B&H charges NY sales tax only. Their price is $50 off standard MSRP for this model... Read more
13-inch 2.0GHz Apple MacBook Pros on sale for...
B&H has the non-Touch Bar 13″ 2.0GHz MacBook Pros in stock today and on sale for $100 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 13″ 2.0GHz MacBook Pro Space Gray (... Read more
15-inch Touch Bar MacBook Pros on sale for up...
B&H Photo has the new 2016 15″ Apple Touch Bar MacBook Pros in stock today and on sale for up to $150 off MSRP. Shipping is free, and B&H charges NY sales tax only: - 15″ 2.7GHz Touch Bar... Read more

Jobs Board

*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 55676865 Los Angeles, California, United States Posted: Feb. 22, 2017 Weekly Hours: 40.00 **Job Summary** As an Apple Read more
Programmer/Editor *Apple* Music Dance - App...
# Programmer/Editor Apple Music Dance Job Number: 55565967 Culver City, California, United States Posted: Feb. 23, 2017 Weekly Hours: **Job Summary** Apple Music Read more
Digital Marketing Specialist - *Apple* iClo...
# Digital Marketing Specialist - Apple iCloud Job Number: 54729233 Culver City, California, United States Posted: Feb. 22, 2017 Weekly Hours: 40.00 **Job Summary** Read more
Marketing Specialist, iTunes & *Apple*...
# Marketing Specialist, iTunes & Apple Music Job Number: 55704205 Culver City, California, United States Posted: Feb. 23, 2017 Weekly Hours: 40.00 **Job Summary** Read more
*Apple* Wireless Lead - T-ROC - The Retail O...
…of knowledge in wireless sales and activations to the Beautiful and NEW APPLE Experiencestore within MACYS. THIS role, APPLE Wireless Lead, isbrandnewas MACYS Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.