TweetFollow Us on Twitter

Mac in the Shell: Automation Potpourri

Volume Number: 23 (2007)
Issue Number: 06
Column Tag: Mac in the Shell

Automation Potpourri

Shell and GUI scripting come together

by Edward Marczak

Introduction

Last month, I gave an overview of some commands that I felt just didn't have the coverage and documentation that they deserved. The theme this month is commands that enable us to tie our shell scripts into the GUI. While I'm an advocate for good ole bash scripting, there are times when it's easier or better for some reason to tie in a GUI app. Think about scripting Safari, Address Book or Excel using familiar utilities in the shell. What about incorporating an AppleScript into a workflow with data piping in and out of it? If that sounds like a panacea, read on!

AppleScript

Under OS X, AppleScript is the clear reach-into-just-about-anything scripting technology. Why choose bash scripting over AppleScript? Let me enumerate some ways:

Portability.

Existing stock snippets.

Speed.

Familiarity.

Ability to do things that AppleScript alone can't do.

Since the addition of 'do shell script' to AppleScript, there's little we can't coerce it into doing. This allows us to call a shell script from within AppleScript and return the results. What a powerful combination. That's great when the logic and script itself lie mainly in AppleScript. However, what if the situation were reversed? What if you have a lengthy shell script that needs to utilize an AppleScript? Enter 'osascript'.

osascript allows us to execute AppleScript commands and scripts from a standard shell. In the it's-getting-better-all-the-time category, as of 10.4 ("Tiger"), you can pass arguments into osascript, and AppleScript can pick them up in the 'argv' variable. It can run simple AppleScript commands all in one shot, or, it can run a script file. Let's see an example:

osascript -e "tell application \"Safari\" to launch"

That's about as simple as it gets. Standard shell conventions apply, so make sure you escape quotes and other special characters. The "-e" flag is used to denote a 'command,' or line in the script. Scripts that need multiple lines need multiple "-e" flags. For example, look at this command:

osascript -e 'tell application "Finder"' -e 'make new Finder window to folder "Applications" of startup disk' -e 'end tell'

Three lines of AppleScript, three "-e" switches. Note the use of single quotes here to avoid the pain of escaping double quotes. Naturally, you probably want to put lengthy or complex scripts into their own file. So, the previous example could have been its own file:

new_app_win.scpt
tell application "Finder"
   make new Finder window to folder "Applications" of startup disk
end tell

This could then be invoked as "osascript new_win_app.scpt". Pretty handy. (Of course, this contrived example could be replicated easily in the shell alone as "open /Applications").

The Real Power

So, rather than come up with anything too contrived, let's explore where you may really use this. Let's take a look at a script that, in part, I really use.

Once upon a time, I had a script that mashed and mangled a bunch of data nightly. It would get this data from various data sources: MySQL, text files and the web. For the web sources, I simply used curl to fetch the data I needed as CSV files. Well, one day, my script stopped working. Why? Security. The web site in question required a certain login sequence, and tokens were generated for each form and page load so they couldn't be forged. Consequently, I needed a 'real' browser to do this part. Safari and AppleScript to the rescue. I was able to keep my shell script in place and largely untouched. I did need to swap out the curl calls, of course, and replace them with osascript auto_web_dl.scpt. The AppleScript file scripts Safari to load pages, click links and save the resulting file. Let's dissect:

auto_web_dl.scpt

on run argv
   tell application "Safari"
      activate
      -- Initial load
      set URL of document 1 to "http://some.example.com/page/"
      repeat until do JavaScript "document.readyState" in document 1 is "complete"
      end repeat
      delay 5
      
      -- click the link
      set URL of document 1 to do JavaScript "documents.links[3].href" in document 1
      repeat until do JavaScript "document.readyState" in document 1 is "complete"
      end repeat
      delay 5
      
      -- load the reports verification page
      set URL of document 1 to "https://setup.example.com/¬
accounting/check? done=http%3a//some.example.com%2Faccouting%2Freports" repeat until do JavaScript "document.readyState" in document 1 is "complete" end repeat delay 5 -- fill in the values do JavaScript "document.getElementById('realm').value = 'ap'" in document 1 do JavaScript "document.getElementById('history').value = '1'" in document 1 do JavaScript "document.settings_form.submit()" in document 1 repeat until do JavaScript "document.readyState" in document 1 is "complete" end repeat delay 5 -- get the reports page set URL of document 1 to "http://some.example.com/accounting/¬
cur_report?export=true&level=sub" repeat until do JavaScript "document.readyState" ¬
in document 1 is "complete" end repeat delay 10 -- save the contents set theSaveName to "acct_nightly.csv" set theSavePath to (path to desktop folder as string) & theSaveName tell application "Safari" save document 1 in file theSavePath end tell tell application "Finder" if file (theSavePath & ".download") exists then set name of file (theSavePath & ".download") to theSaveName end if end tell end tell end run

(A big thank you to Ben Waldie from automatedworkflows.com for teaching me how to get Safari to save a plain text document! Not being an AppleScript person by nature, I just couldn't nail it down).

So, yes, this took a little knowledge of JavaScript and Document Object Model. Not terribly esoteric, but if you're solely a bash scripting person, this may be a bit foreign. Now, my shell script remained in bash, and runs as a nightly cron job that delivered reports to company executives. The abridged version is now this:

#!/bin/bash
# Grab initial MySQL data
mysqldump -u db_user...> /data/table1.csv
# Grab web data
curl —LO http://financialinfo.example.com/stocks.php?id=2345
# Grab accounting data
osascript auto_web_dl.scpt
# Process results
/usr/local/bin/data_process /data

Further Interaction

More than just being able to call AppleScript from the shell, there are several ways to pass variables between the two environments. The first is a natural extension of what you know from bash. Simply put the bash variable on the command line:

$ osascript -e 'tell application "Finder"'¬ 
-e "display dialog \"Hello, $USER\"" -e 'end tell'

This will display a dialog box in the Finder containing the name of the currently logged-in shell user. Notice also, that when this is run, osascript returns values to the shell. Again, of course, you can use or discard these values as the situation dictates. Note that this is a valid way to pass data out of AppleScript and back into the shell.

Look at the possibilities this opens up! Take, for example, the following script:

#!/bin/sh
for user in $(dscl /LDAPv3/127.0.0.1 -list /Users)
do
        ma=$(dscl /LDAPv3/127.0.0.1 -read /Users/$user mail)
        osascript -e "tell application \"System Report\" process $ma"
done

Here, we use bash and dscl to pull all users from Open Directory and then feed each of those into the fictitious application "System Report".

Another way to pass data between the two environments is via environment variables. AppleScript will happily reach out and grab environment variables from a shell using the system attribute variable. Let's say each user on the system has environment variable defined for their favorite color called, "my_color ". Without passing it in as an argument, AppleScript can access it like this:

set favorite_color to system attribute "my_color"

You can then go on and have AppleScript make decisions based on your new variable.

Finally, you can pass and values into the AppleScript as arguments. Given the following AppleScript:

on run argv
   tell application "System Events"
      repeat with currentArg in (every item of argv)
         display dialog currentArg
      end repeat
   end tell
end run

It could be called like this:

osascript asarg.scpt mike bill joe

This will cause three dialog boxes to appear, each containing one of the arguments passed in.

The trick here is wrapping everything in the "on run argv" block. Since argv is an AppleScript list, you can access any element directly. For example, argument one is simply, "item 1 of argv".

In Conclusion

I hope this short, but important topic, stirs some ideas in your head. These techniques truly make the scripting environment boundless. While there are many, many cases where you can script a workflow entirely in bash, or entirely in AppleScript, they are also many reasons to integrate the two. I talk consistently about remote management and troubleshooting of Macintosh systems. This is yet another great weapon in your arsenal. With only command line access, you can now launch applications, interact with them, and the user sitting at the console.

Using osascript also allows AppleScript into places that it is usually not allowed in. Think about a user interacting with a web page, and one of their actions runs an AppleScript. You can also use osascript to interact with users at important times. You can display a dialog box prior to running a CPU intensive cron job. This trick also comes in handy to alert users of actions being taken during login hooks.

One thing to note, though: while the data coming out of osascript is on stout, osascript has no concept of stdin. So, you need to use one of the techniques covered here to get data into an AppleScript. You just can't pipe your data in. (OK, in all fairness, you could get data into an AppleScript by reading a file or through sockets, etc. — just not via stdin!).

Don't forget: interaction with osascript isn't just limited to bash and its constructs. Take a look at this great example from Apple's own, "AppleScript Overview":

osascript -e 'tell app "Address Book" to get the name¬ 
of every person' | perl -pe 's/, ¬
/\n/g'| sort | uniq —d

This one liner will output duplicate entries from your address book. While I'm sure this could have been scripted entirely in AppleScript, it's unlikely that it would have been as concise or elegant as this one-liner.

The point is simple: mix and match as needed to solve the problem at hand. You have many varied tools at your disposal, each with particular strengths, advantages and weaknesses.

Media of the month: It's Johnny Cash month! If you've never listened to, "At Folsom Prison", do yourself a favor and experience it. If you know virtually nothing of the man, go rent "Walk the Line".


See you next month, post WWDC!

Ed Marczak owns and operates Radiotope, a technology consultancy specializing in automating business processes and enabling communications between employees and clients. Communicate at http://www.radiotope.com.

 

Community Search:
MacTech Search:

Software Updates via MacUpdate

How to upgrade your character in Spellsp...
So you’ve mastered the basics of Spellspire. By which I mean you’ve realised it’s all about spelling things in a spire. What next? Well you’re going to need to figure out how to toughen up your character. It’s all well and good being able to spell... | Read more »
5 slither.io mash-ups we'd love to...
If there's one thing that slither.io has proved, it's that the addictive gameplay of Agar.io can be transplanted onto basically anything and it will still be good fun. It wouldn't be surprising if we saw other developers jumping on the bandwagon,... | Read more »
How to navigate the terrain in Sky Charm...
Sky Charms is a whimsical match-'em up adventure that uses creative level design to really ramp up the difficulty. [Read more] | Read more »
Victorious Knight (Games)
Victorious Knight 1.3 Device: iOS Universal Category: Games Price: $1.99, Version: 1.3 (iTunes) Description: New challenges awaits you! Experience fresh RPG experience with a unique combat mechanic, packed with high quality 3D... | Read more »
Agent Gumball - Roguelike Spy Game (Gam...
Agent Gumball - Roguelike Spy Game 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: Someone’s been spying on Gumball. What the what?! Two can play at that game! GO UNDERCOVERSneak past enemy... | Read more »
Runaway Toad (Games)
Runaway Toad 1.0 Device: iOS Universal Category: Games Price: $2.99, Version: 1.0 (iTunes) Description: It ain’t easy bein’ green! Tap, hold, and swipe to help Toad hop to safety in this gorgeous new action game from the creators of... | Read more »
PsyCard (Games)
PsyCard 1.0 Device: iOS Universal Category: Games Price: $1.99, Version: 1.0 (iTunes) Description: From the makers och Card City Nights, Progress To 100 and Ittle Dew PSYCARD is a minesweeper-like game set in a cozy cyberpunk... | Read more »
Sago Mini Robot Party (Education)
Sago Mini Robot Party 1.0 Device: iOS Universal Category: Education Price: $2.99, Version: 1.0 (iTunes) Description: -- Children's Technology Review Editor's Choice -- | Read more »
How to get a high score in every level o...
Sky Charms is an adorable match three puzzler that provides a decent challenge thanks to its creative level design. It regularly presents something new, forcing you to think on your feet. [Read more] | Read more »
Apestorm: Full Bananas (Games)
Apestorm: Full Bananas 1.0 Device: iOS Universal Category: Games Price: $.99, Version: 1.0 (iTunes) Description: ***Launch sale – limited time only!*** Fugitive Apes have taken to the skies in search of revenge after humans have... | Read more »

Price Scanner via MacPrices.net

Apple restocks Certified Refurbished Mac mini...
Apple has restocked Certified Refurbished 2014 Mac minis, with models available starting at $419. Apple’s one-year warranty is included with each mini, and shipping is free: - 1.4GHz Mac mini: $419 $... Read more
15-inch 2.2GHz Retina MacBook Pro on sale for...
Amazon.com has the 15″ 2.2GHz Retina MacBook Pro on sale for $1699.99 including free shipping. Their price is $300 off MSRP, and it’s the lowest price available for this model from any reseller (and... Read more
Apple Beats Microsoft at Own Game; Amazon Pri...
First quarter seasonality combined with an overall disinterested customer base led to an annual decline of 14.7% in worldwide tablet shipments during the first quarter of 2016 (1Q16). Worldwide... Read more
Tablets Had Worst Quarter Since 2012, says St...
The global tablet market began 2016 just as 2015 left off, down. Tablet shipments fell 10% to 46.5 million units during the Q1 2016, according to the new “Preliminary Global Tablet Shipments and... Read more
Clearance 13-inch MacBook Airs, Apple refurbi...
Apple recently dropped prices on certified refurbished 2015 13″ MacBook Airs with 4GB of RAM with models now available starting at $759. An Apple one-year warranty is included with each MacBook, and... Read more
Clearance 12-inch Retina MacBooks, Apple refu...
Apple has dropped prices on Certified Refurbished 2015 12″ Retina MacBooks with models now available starting at $929. Apple will include a standard one-year warranty with each MacBook, and shipping... Read more
Aleratec Releases Mac Software Upgrade for 1...
California based Aleratec Inc., designer, developer and manufacturer of Portable Device Management (PDM) charge/sync products for mobile devices and professional-grade duplicators for hard disk... Read more
Sale! Amazon offers 27-inch iMac, 13-inch 2.9...
Amazon has the 27″ 3.2GHz 5K iMac and the 13″ 3.9GHz Retina MacBook Pro on sale for $300 off MSRP, each including free shipping, for a limited time: - 27″ 3.2GHz/1TB HD 5K iMac (model MK462LL/A): $... Read more
Apple refurbished 13-inch Retina MacBook Pros...
Apple has Certified Refurbished 13″ Retina MacBook Pros available for up to $270 off the cost of new models. An Apple one-year warranty is included with each model, and shipping is free: - 13″ 2.7GHz... Read more
13-inch 2.7GHz/128GB Retina MacBook Pro on sa...
Take $200 off MSRP on the price of a new 13″ 2.7GHz/128GB Retina MacBook Pro (model MF839LL/A) at Amazon. Shipping is free: - 13″ 2.7GHz/128GB Retina MacBook Pro: $1099.99 $200 off MSRP Act now if... Read more

Jobs Board

Automotive Sales Consultant - Apple Ford Linc...
…you. The best candidates are smart, technologically savvy and are customer focused. Apple Ford Lincoln Apple Valley is different, because: $30,000 annual salary Read more
*Apple* Retail - Multiple Positions - Apple,...
Job Description: Sales Specialist - Retail Customer Service and Sales Transform Apple Store visitors into loyal Apple customers. When customers enter the store, Read more
*Apple* Solutions Consultant - Apple (United...
# Apple Solutions Consultant Job Number: 48260200 Phoenix, Arizona, United States Posted: Apr. 22, 2016 Weekly Hours: 40.00 **Job Summary** As an Apple Solutions Read more
Restaurant Manager (Neighborhood Captain) - A...
…in every aspect of daily operation. WHY YOU'LL LIKE IT: You'll be the Big Apple . You'll solve problems. You'll get to show your ability to handle the stress and Read more
Simply Mac *Apple* Specialist- Service Repa...
Simply Mac is the largest premier retailer of Apple products in the nation. In order to support our growing customer base, we are currently looking for a driven Read more
All contents are Copyright 1984-2011 by Xplain Corporation. All rights reserved. Theme designed by Icreon.