system/bin/screencap -p crash.png


shell@DemeterUHD:/sdcard/Pictures $ screencap --help
screencap: invalid option -- -
usage: screencap [-hp] [-d display-id] [FILENAME]
   -h: this message
   -p: save the file as a png.
   -d: specify the display id to capture, default 0.
If FILENAME ends with .png it will be saved as a png.
If FILENAME is not given, the results will be printed to stdout.