MikeSpike.org » leopard

Selecting audio ports on Mac Pro’s in lab environments.

Michael — Mon, 01 Dec 2008 23:04:55 +0000

Where I work, Apple computers is the standard for Communications majors. That being said, we’ve got a few labs with Mac Pro’s and 13 individual editing suites. The edit suites provide the students with a cubical shunned away from the world by a sliding glass door allowing their video creativity juices to flow. In the labs, there is a desktop at the front of the room dedicated for the teacher with wall-mounted speakers and a projector. Although all this hardware looks great on the outside, one issue that came up was audio. Since the change to Intel chips, the three audio sources (headphone, audio speaker and line-out) which if you remember, would auto-switch based on what was plugged in, has now changed to three independent sources. What this means is if a user wants to make any changes to how audio gets routed they must make the change manually. To add to this issue, my environment consists of users logging in individually every time they use a machine whether it’s in a classroom or in an editing suite. If the audio changes were a global change, I wouldn’t be having this issue; but because it has a default value (front speaker jack) for each person that logs in, I’m stuck with another problem. Which if you are thinking, I’m leaving all my grunts and complaints about OSX’s “features” in a lab environment for another blog post.

Software named Soundsource made by Amoeba makes the change pretty simple by adding an icon on the toolbar. This is a pretty slick piece of software, but this still doesn’t fulfill the user login for teacher stations in the classrooms and the editing suites which have rear speaker input. You can suggesting plugging the speakers into the front plug, but give it a day and someone would have pulled it out.

In my search for solutions, I pondered if there was any way to change the audio configuration via command line. This would at least make it a viable option to use a launchd user agent once the user logs in. Scouring the internet, which I must say I do a pretty good job, I found a utility called Switchaudio. This small utility is just what I’ve been looking for. It adds a way to select the input or output audio sources from the available sources (as shown on the right). After this, everything else fell into place. I ended up putting this file in the /usr/bin directory to make the utility easily accessible. Then I created a launchd user agent using Lingon so whenever a user logs on, the output audio changes to whatever I want (in this case “Built-in Line Output”).

Lastly, to make the changes in the affected labs and 13 video editing suites, I made a package installer and pushed it out using Remote Desktop.

Pretty simple once I figured it out…

Log into a mac using ARD’s “send unix command.”

Michael — Tue, 21 Oct 2008 20:43:16 +0000

I stumbled across this useful little tidbit of knowledge. Have you ever needed to log into several machines in a lab but hated going to each one and typing in your credentials. Well thanks to “David Kahn3″ and others for coming up with the following script,

osascript < tell application “System Events”
keystroke tab
keystroke (ASCII character 8 )
keystroke tab
keystroke (ASCII character 8 )
keystroke return
delay 0.5
keystroke tab
keystroke “username”
keystroke tab
delay 0.5
keystroke “password”
delay 0.5
keystroke return
keystroke return
keystroke return
keystroke return
end tell
EOF

I was able to push this script out using Apple Remote Desktop (run as root not admin) to my macs while they were at the login screen window. Just a few changes for the account username/password fields and bam the computers logged in without me having to even touch them.Beautiful

Original Post from Apple Support

OSX Leopard, Deep Freeze and Active Directory… oh my

Michael — Wed, 13 Aug 2008 02:25:06 +0000

With the never ending roadblocks I encounter at work, my task this year was to utilize the new 10.5 Leopard operating system (and then some) for a local private university. I’ve used Deep Freeze for many years and it has proved to be a great asset in keeping lab machines consistent. What the Macs haven’t utilized was a way for users to log-in with their username and password. Being a predominant PC campus, Active Directory (AD) will be the choice of Mac’s Directory Service. With all the bad rap Leopard got with Active Directory not working, I luckily was able to get 10.5.4 to bind fine with AD. Glancing into Directory Utility the light was green, all is good.

I then sent out the command through Remote Desktop to freeze the machines with Deep Freeze. Moving on to other labs I noticed after 10ish days people started reporting that they could no longer log into the computers that I had initially setup. Going into Directory Services it showed a red light with the message “This server is not responding.” Grrrrrr

Unbinding the machines then rebinding the machine solved this problem but doing this every so often across the campus would be crazy.

After searching the net, I found from my PC coworkers that they had to modify the registry on the window machines to set DisablePasswordChange to 1 in order to keep the trust between the bind to AD. Keep in mind this is all because of Deep Freeze protecting the drive from modifications. I looked hard into dsconfigad on the Macs and stumbled across an attribute called -passinterval days. This basically allows you to change the amount of days the computer will trust an account password bound to AD. By default, the amount of days the passinterval was set to change was 14, explaining why my machines were no longer connecting to the Active Directory on campus. So I sent out the command to the labs that I’ve completed so far thus this should fix the issue. One problem down…..

Hopefully this will help anyone else that is stuck in the same situation as me.