Revert grep target; instead add caveat for Ubuntu.

articles/virtual-machines-linux-how-to-attach-disk.md

@@ -25,7 +25,10 @@ You can attach both empty disks and disks that contain data. In both cases, the
 
 2. In the SSH window, type the following command, and then enter the password for the account that you created to manage the virtual machine:
 
-		# sudo grep SCSI /var/log/syslog
+		# sudo grep SCSI /var/log/messages
+
+	>[AZURE.NOTE] For recent Ubuntu distributions you may need to use `sudo grep SCSI /var/log/syslog` as logging to `/var/log/messages` may be disabled by default. 
+
 
 	You can find the identifier of the last data disk that was added in the messages that are displayed.