android: howto dump logcat to file

adb logcat *:I -d >log.txt

*:I    all tags' log level above 'Info'
-d > log.txt    dump to file log.txt

http://developer.android.com/guide/developing/tools/adb.html#logcat

DDMS is not reliable esp. for showing very frequent log display.
If frequent log analysis is required, I use adb logcat dump instead.