Dismount/Mount External SD Card from command line or script

Hi all.

Does anyone know how to dismount/mount the external SD card from the command line? umount gives me the following error:

Code:

---

umount /dev/block/vold/public:179,1
umount: /mnt/secure/asec: Device or resource busy

---

I can dismount it from the settings app under storage, but I'd like to use a script to dismount it, run fsck against it, and then mount it again.\\

Any tips appreciated!

Thanks.

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