logcat

displays Android system and application logs

TLDR

View all logs

$ adb logcat

Show only one tag, silencing everything else

$ adb logcat -s [TAG]

Show only errors and above

$ adb logcat "*:E"

Show a tag at debug level and silence the rest

$ adb logcat [TAG]:D "*:S"

Show logs from a single app by process ID

$ adb logcat --pid=$(adb shell pidof -s [com.example.app])

Dump the current log and exit

$ adb logcat -d > [logfile.txt]

Show the last lines and exit

$ adb logcat -t [100]

Clear the log buffers

$ adb logcat -c

Show the crash buffer only

$ adb logcat -b crash

Filter lines with a regular expression

$ adb logcat -e "[pattern]"

Use a colored output format with timestamps

$ adb logcat -v color,time

SYNOPSIS

adb [shell] logcat [options] [filterspec...]

logcat displays Android system and application logs. It runs on the device and is usually invoked from a host through adb logcat, which is shorthand for adb shell logcat.Messages are read from the ring buffers kept by the logd daemon. Each message has a tag and a priority, and filter specifications of the form tag[:priority] select what is printed. A bare tag means tag:V, and a bare `*` means `*:D`. If no filterspec is given, $ANDROID_LOG_TAGS is used.Available options depend on the Android version of the device; run adb logcat --help for the exact list.

PARAMETERS

-s

Set the default filter to silent (like `*:S`). Combined with tags, only those tags are shown.

-b, --buffer buffer

Ring buffer(s) to read: main, system, radio, events, crash, default, all (plus kernel and security on some builds). Repeatable or comma separated. Default is main,system,crash.

-c, --clear

Clear (flush) the selected buffers and exit.

-d

Dump the log and exit instead of blocking.

-L, --last

Dump logs from before the last reboot (pstore).

-f, --file file

Write to file instead of stdout.

-r, --rotate-kbytes N

Rotate the log file every N KiB (requires -f).

-n, --rotate-count N

Maximum number of rotated logs (default 4).

-v, --format format

Output format: brief, long, process, raw, tag, thread, threadtime (default), time. Modifiers: color, descriptive, epoch, monotonic, printable, uid, usec, UTC, year, zone.

-D, --dividers

Print dividers between log buffers.

-B, --binary

Output the log in binary.

-e, --regex expr

Only print lines matching an ECMAScript regex.

-m, --max-count N

Exit after printing N lines.

-t N | time

Print the most recent N lines, or lines since time ('MM-DD hh:mm:ss.mmm'), then exit (implies -d).

-T N | time

Like -t but keeps following the log.

--pid pid

Only print logs from the given process ID.

--uid uids

Only print logs from the given comma-separated numeric UIDs.

-g, --buffer-size

Print the size of the ring buffers.

-G, --buffer-size=size

Set the ring buffer size (suffix K or M).

-S, --statistics

Print logging statistics.

-p, --prune / -P 'list'

Get or set the prune (allow/deny) rules.

--wrap

Sleep for 2 hours or until the buffer is about to wrap.

PRIORITY LEVELS

V: VerboseD: DebugI: InfoW: WarningE: ErrorF: FatalS: Silent (suppress all output)

CAVEATS

Requires an adb connection (or a shell on the device). Buffers are small ring buffers, so older messages are overwritten, and logs are lost on reboot unless read with -L. Apps can only see their own logs; reading other apps' logs requires adb, root, or the READ_LOGS permission. Many logd control options require root.

HISTORY

logcat is part of the Android platform, developed by Google. It has been the primary Android logging tool since Android's release in 2008. The logd daemon replaced the old kernel logger driver in Android 5.0.

RESOURCES

Documentation