What is Android Logging System and where the logs are saved in Android

Overview of Android Logging System:

What is Android Logging System?

• Provide a mechanism for collecting and viewing system debug output.
•  Logs from various applications and portions of the system are collected in a series of circular buffers, which then can be viewed and filtered by the logcat command.

Android Logging System

Introduction: 

The logging system consists of a kernel driver and kernel buffers for storing log messages:

• HoneycombMR2Src/kernel/drivers/staging/android/logger.c
• Create “/dev/log” folder in handle_device_event() of AndroidSrc/system/core/init/devices.c 

C/C++/Java APIs and classes: 

• For making log messages
• For accessing the log messages

logcat, the command for viewing log messages  AndroidSrc/system/core/logcat/

Ability to view and filter the log messages from the host machine (via Eclipse-ADT or DDMS)

Log device files

4 channels, each have a Ring/Circular Buffer:

• /dev/log/radio – radio&phone-related messages (64KB)
• /dev/log/events – system/hardware events (256KB)
• /dev/log/system –framwork or low-level system messages (64KB)
• /dev/log/main – everything else (64KB)

The maximum log message size of each channel is specified in kernel driver(logger.c)

File permission of each(radio/events/system/main) is 0662 (rw-rw-w)