如下所示，高手求解，怎么互换sd卡，下面是安卓机的读取sd卡数据结构，求解！！！！有奖励！！！！！！！！！！！！！
## Vold 2.0 Generic fstab
## - San Mehat (san@android.com)
##
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## Regular device mount
##
## Format: dev_mount <label> <mount_point> <part> <sysfs_path1...>
## label - Label for the volume
## mount_point - Where the volume will be mounted
## part - Partition # (1 based), or ‘auto‘ for first usable partition.
## <sysfs_path> - List of sysfs paths to source devices
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## Example of a standard sd* mount for the emulator / Dream
# Mounts the first usable partition of the specified device
dev_mount sd* /storage/sd*0 emmc@fat /devices/platform/goldfish_mmc.0 /devices/platform/mtk-msdc.0/mmc_host
dev_mount sd*2 /storage/sd*1 auto /devices/platform/goldfish_mmc.1 /devices/platform/mtk-msdc.1/mmc_host
## Example of a dual * setup
# dev_mount left_sd* /mnt/sd*1 auto /devices/platform/goldfish_mmc.0 /devices/platform/mtk-sd.0/mmc_host/mmc0
# dev_mount right_sd* /mnt/sd*2 auto /devices/platform/goldfish_mmc.1 /devices/platform/mtk-sd.2/mmc_host/mmc2
## Example of specifying a specific partition for mounts
# dev_mount sd* /mnt/sd* 2 /devices/platform/goldfish_mmc.0 /devices/platform/msm_sdcc.2/mmc_host/mmc1