root@spark:~# grab -h
Usage: grab [commands] [filename]

command:
-o only grab osd (framebuffer) when using this with png or bmp
fileformat you will get a 32bit pic with alphachannel
-v only grab video
-d always use osd resolution (good for skinshots)
-n dont correct 16:9 aspect ratio
-r (size) resize to a fixed width, maximum: 1920
-l always 4:3, create letterbox if 16:9
-b use bicubic picture resize (slow but smooth)
-j (quality) produce jpg files instead of bmp (quality 0-100)
-p produce png files instead of bmp
-q Quiet mode, don't output debug messages
-s write to stdout instead of a file
-h this help screen

If no command is given the complete picture will be grabbed.
If no filename is given /tmp/screenshot.[bmp/jpg/png] will be used.
root@spark:~#