Logcat & Debugging Android 1.0+ Risk: READ_ONLY

View Android System Logs (Logcat)

Streams real-time system log messages, app traces, and crash stack traces.

Command Syntax

adb logcat

Generic Syntax: adb logcat [options] [filterspecs]

Options & Parameters

Flag	Description
-s	Silent mode: filter only tags explicitly specified.
-d	Dump log buffer to screen and exit immediately (no streaming).
-c	Clear (flush) the entire logcat ring buffer.
-f <FILE>	Write log output to specified file on device.
-v <FORMAT>	Set log format (time, threadtime, color, epoch, raw, json).
-b <BUFFER>	Select specific buffer (main, system, radio, events, crash, all).
--pid <PID>	Filter log entries produced by a specific process ID.
-g	Print the size of the ring buffer and its current utilization.

Real-World Usage Examples

Stream all error logs (*:E)

Filters stream to only Error and Fatal priority logs.

adb logcat *:E

Output:

08-25 12:19:01.120  1420  1455 E AndroidRuntime: FATAL EXCEPTION: main
Process: com.example.app, PID: 4120
java.lang.NullPointerException: Attempt to invoke virtual method on a null object reference

Filter logs by specific tag and priority

Shows only logs tagged MyTag (Debug+) or ActivityTaskManager (Info+).

adb logcat -s "MyTag:D" "ActivityTaskManager:I"

Output:

08-25 12:20:15.842  2100  2100 D MyTag   : Network payload received: 200 OK

Filter by Process ID (PID)

Streams logs generated exclusively by process 4120.

adb logcat --pid=4120

Output:

08-25 12:20:18.910  4120  4120 I MyTag   : Initializing UI controller