How do you detect if something is connected to a USB drive?

[laredotornado]

Hi,

I'm using Mac 10.7.5. Per my other posts, I'm trying to write a bash (or other suitable) shell script to conditionally launch an application. The launch is contingent upon whether there is the apporpriate device connected to one of the USB drives. How can I detect what is connected through a script?

Thanks, - Dave

[DeltaMac]

Your description is a little fuzzy. I don't know of other devices that can be connected to an already-connected USB drive, as USB doesn't offer "daisy-chain" capabilities, as far as I know.
So, can I say that you want to write a script that will detect that a USB mass storage device is already connected, and also when a USB device is added to your computer? Are you only interested in mass storage, or are there other USB devices that you want to know about?
Keep in mind that a Mac laptop might already have as many as 6 USB devices on the USB bus, before you have anything attached externally.
So, what, exactly, do you consider an "appropriate device"?

[NovaScotian]

You can use launchd (via Lingon 3) to run a script whenever a particular drive is connected -- that's how my backups work.

[NaOH]

Likewise, there's the Do Something When add-on for System Preferences which can easily be set up to launch an application when a volume mounts.

http://www.azarhi.com/Projects/DSW/index.php

It hasn't been updated in a while, but it still works fine under 10.7, just needing System Preferences to run in 32-bit mode.

[NovaScotian]

It still works in Mountain Lion. When you double-click it in System Preferences, a drop-down sheet like the one below drops. It simply restarts System Preferences in 32-bit mode and after a pause, you get the DSW window.

[hayne]

I'd tend to just try doing whatever operation it does and then deal with the error condition if there is no USB device etc.

[laredotornado]

Hi,

DeltaMac, I have a device called MagicJack that alows me to make phone calls from my computer. When you plug the device into your USB port, you can then launch an application that lets you make phone calls. I was looking for a scriptable way to launch this application at system startup. I found out that when the device gets plugged in, there is something at "/Volumes/magicJack."

NaOH, I tried "Do Somewhen When" and set up a rule (see the attached file), but unfortunately, my app didn't launch when I rebooted my computer.

THanks for the ideas, - Dave

[NaOH]

Since I don't have the device or application for testing, make certain you have the volume and application names perfectly correct. It looks like you do, but it's worth confirming on your end.

[NovaScotian]

Why not just set the app to start at login in System Preferences > Accounts > Login Items?

[laredotornado]

The reason I don't have the app always start at login is because sometimes the device is not connected and so launching the app would be useless since it wouldn't do anything (both the app have to be launched and teh device connected in order to make phone calls)

[NovaScotian]

Then post #3 above is your answer -- Lingon is a simple program for setting up launchd conditions. When you plug in the device or when it's discovered at login, it will launch the program.

[laredotornado]

Does Lingon make a distinction between system startup and user login? I created a Lingon "My Agent" using this script

[ -d /Volumes/magicJack ] && /Users/davea/.magicJack/Softphone/magicJack.app/Contents/MacOS/magicJack || echo "File does not exist" > /Users/davea/magic.out

(complete description is attached) but the script isn't executing properly (the app doesn't launch when I'm log in). However, when I run that script at a terminal, everythign runs fine. I think Lingon may be executing it at system startup and I would prefer it execute it at user login. Any way I can control that?

Thanks, - Dave

[NovaScotian]

Which of the boxes in the figure below did you check? Note that there is one for login.