how to run linux command to mount and unmount sd card on android 3.x

Question

I would like to know how I can run linux command to mount / unmount specific path on the sdcard, or even the whole sdcard. tried a lot of things people suggested, but nothing really worked.

my device is rooted.

my goal is to prevent access to some folders on sdcard from desktop and local apps that displaying file system browsing.

any idea (beside file encryption) to achieve this goals in other ways - are welcome.

Answer 1

This will not work well, as the filesystem lacks a permission model.

You can however partition the physical media and create a unix style filesystem with permissions on part of it. Many custom roms did this, especially for apps2sd before the official method came out. Look there for the details of reconfiguring vold.

Or you could look into what Google engineers have said about transitioning Android bulk storage to a scheme where the base filesystem has permissions and the impression of one without is emulated on top of it for legacy support.