SD cards have a simple way to write a string to a file it?

Because there is no usb data cable, log.i output invisible, going to write debug data to an SD card, a friend did it?<-! Main posts under Banner (D4) -><-! Posts under the main text (D5) ->
Reply:
alogcat.apk
Or wirelessadb.apk
Reply:
Direct write chanting
We need to add a log to a text in the presence of sd card