ADB Shell In Recovery Mode - Error:Closed I smashed my display pretty good today and am unable to use the digitizer. The upper half of the screen is barely visible and the lower half is black. I have debugging enabled on the phone but I can't push the button to accept the key when the phone is connected to the computer. So, I am unable to gain access to my data/texts while I wait on my new phone. I found a blog post where the guy walks through a whole series of commands to permanently enable debug mode on his phone through use of adb in recovery. 

Fortunately I am able to use the volume, home and power keys to boot into recover. I am also able to read enough of the screen to make the selection to "apply update from ADB". Once I select this I run...

adb devices


...where my device is listed with a status of sideload. All seems good until I attempt to do anything else. Issuing...

adb shell


... returns error:closed as does pretty much any other command. 

Any thoughts as to what I may be doing wrong?
You're not doing anything wrong. You're most likely using a stock recovery. Access to shell can prove to be  potentially dangerous when it comes to userdata so a lot of OEMs or vendors (I don't know the correct term) prefer to ship a locked-down stock recovery which would do what OEM wants them to do, such as flashing OTA updates, sideloading updates from OEM, doing factory reset and in some cases, some hardware testing options. That's the scope they follow.

If you want unconditional shell access, you would've to flash a custom recovery.