Please tell me if there's a better way than this:
edit libgphoto2-2.5.4\camlibs\ptp2\library.c and add the lines marked by "+":
{"Sony:Alpha-A3000", 0x054c, 0x074e, 0}, + + /* Sony alpha 6000: JB and DC added 2014-05-19 */ + {"Sony:Alpha-A6000", 0x054c, 0x094e, PTP_CAP}, /* Nikon Coolpix 2500: M. Meissner, 05 Oct 2003 */
Then run
cd libgphoto2-2.5.4 make sudo make install
to install that library where gphoto2 can find it.
IMPORTANT: Turn the mode dial on the top of the camera to "Superior Auto". It definitely won't take snapshots with the mode dial in the "Movie" position.
Then
gphoto2 --capture-image-and-download --force-overwrite --filename test.jpg