[Vibrant Android Development] explodingboy70:
A little light reading because you're interested.

Filtering Log Output

Every Android log message has a tag and a priority associated with it.

The tag of a log message is a short string indicating the system component from which the message originates (for example, "View" for the view system).

The priority is one of the following character values, ordered from lowest to highest priority:

V — Verbose (lowest priority)

D — Debug

I — Info

W — Warning

E — Error

F — Fatal

S — Silent (highest priority, on which nothing is ever printed)

You can obtain a list of tags used in the system, together with priorities, by running logcat and observing the first two columns of each message, given as <priority>/<tag>.

Here's an example of logcat output that shows that the message relates to priority level "I" and tag "ActivityManager":

I/ActivityManager( 585): Starting activity: Intent { action=android.intent.action...} To reduce the log output to a manageable level, you can restrict log output using filter expressions. Filter expressions let you indicate to the system the tags-priority combinations that you are interested in — the system suppresses other messages for the specified tags.

A filter expression follows this format tag:priority ..., where tag indicates the tag of interest and priority indicates the minimum level of priority to report for that tag. Messages for that tag at or above the specified priority are written to the log. You can supply any number of tag:priority specifications in a single filter expression. The series of specifications is whitespace-delimited.

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" or above:

adb logcat ActivityManager:I MyApp:D *:S The final element in the above expression, *:S, sets the priority level for all tags to "silent", thus ensuring only log messages with "View" and "MyApp" are displayed. Using *:S is an excellent way to ensure that log output is restricted to the filters that you have explicitly specified — it lets your filters serve as a "whitelist" for log output.

The following filter expression displays all log messages with priority level "warning" and higher, on all tags:

adb logcat *:W If you're running logcat from your development computer (versus running it on a remote adb shell), you can also set a default filter expression by exporting a value for the environment variable ANDROID_LOG_TAGS:

export ANDROID_LOG_TAGS="ActivityManager:I MyApp:D *:S" Note that ANDROID_LOG_TAGS filter is not exported to the emulator/device instance, if you are running logcat from a remote shell or using adb shell logcat.

Controlling Log Output Format

Log messages contain a number of metadata fields, in addition to the tag and priority. You can modify the output format for messages so that they display a specific metadata field. To do so, you use the -v option and specify one of the supported output formats listed below.

brief — Display priority/tag and PID of originating process (the default format).

process — Display PID only.

tag — Display the priority/tag only.

thread — Display process:thread and priority/tag only.

raw — Display the raw log message, with no other metadata fields.

time — Display the date, invocation time, priority/tag, and PID of the originating process.

long — Display all metadata fields and separate messages with a blank lines.

When starting logcat, you can specify the output format you want by using the -v option:

So, you can go into settings and set it up how you prefer. Time, process and so on. You can also set it to save to SD periodically But be careful with that or your SD can be over run with logs.