export SANE_DEBUG_RTS8891=255
export SANE_DEBUG_RTS8891_LOW=255
export SANE_DEBUG_RTS88XX_LIB=255
export LD_PRELOAD=backend/.libs/libsane-rts8891.so
export SANE_CONFIG_DIR=backend
frontend/.libs/scanimage -d rts8891 2>rts8891-scan.log >rts8891-scan.pnm