logcat tutorial

start real time

adb shell

su

adb logcat | findstr com.grabtaxi.driver2

filtering (sample)

logcat ActivityManager:I MyApp:D *:S

Here's an example of a filter expression that suppresses all log messages,
except those with the tag "ActivityManager", at priority "Info" or above, 
and all log messages with tag "MyApp", with priority "Debug" 

https://stackoverflow.com/questions/6854127/filter-logcat-to-get-only-the-messages-from-my-application-in-android