http://www.droidjar.
com/root-samsung-galaxy-core-duos-gt-i8262-and-install-cwm/
!/system/bin/sh
if busybox test ! -f /storage/sdcard0/CWM.img; then
        echo no /storage/sdcard0/CWM.img
        exit 1
fi
cat /storage/sdcard0/CWM.img > /dev/block/mmcblk0p13
sync; sync; sync
echo done