[Eee Pad Transformer Android Development] e154037:
Directory binding through remount no longer works sincd Jelly bean 4.2.1 which added multiuser feature.

However, with help of stickmount (https://play.google.com/store/apps/details?id=eu.chainfire.stickmount&hl=en),

the directory binding becomes possible again. The key point, I believe, is stickmount mount an OTG USB storage as

a subdir under internal sdcard. The procedure is as follows:

Precondition: your device is rooted, has stickmount and termianl emulator installed

Assumption: app XXX uses data file in /sdcard/XXX and you want to move its data to USB storage

step 1: Plugin an OTG USB, stickmount will run and mount it as /sdcard/usbStorage/sda1, check this sub dir with any file

explorer.

step 2: Create a directory XXX under /sdcard/usbStorage/sda1 and copy to it all files and subdir in /sdcard/XXX

step 3: Make /sdcard/XXX empty (Delete all its files and subdirs)

step 4: run terminal emulator in su mode, issue command

mount -o bind /data/media/0/usbStorage/sda1/XXX /data/media/0/XXX

step 5: Run file manager to check directory /sdcard/XXX is binded successfully.

Run your application XXX

My device is ASUS TF101 in EOS4' jellean bean 4.2.1. with a dock. My OTG usb is inserted to the dock.

With stickMount, we can make directory link to folders on OTG card in JB4.2.2. But how about links to folders on external sdcard (extSdCard). In the latter case, FolderMount may come to the rescue. My know FolderMount in a zigzag way. At the begiging, FM did not work on my ASUS TF101 in JB4.2.2 (EOS4). It allowed me to define and activate a directory link, and the link was visible in my file explorer but the files and folders inside could not be accessed unless I turned on the "Root" setting of the explorer. And in the notification area, I saw error message :

Error.extSdCard permission

Problem fixing external sdcard ownership/permission

When FM 2.09 comes out, I tried many times and finally found what was the problem. I had a mount point 'Removable/MicroSD' binding to /dev/block/mmcblk1p1, which was established at boot through Tasker. After removed this bind, FM starts to work fine. The lesson I learned is:

Do not use different user tools to make directory binds to the same extSdCard, or there might be conflict in changing ownership/permission. I am not saying FM is perfect, it is still in development, and it is not the only fish in the sea. What I am trying to say is the time comes to make directory bind in JB4.2.2 with help from stickMount, FolderMount and other good tools.

Notes:

1. App "Directory Bind" (http://xdaforums.com/showthread.php?t=1410262) still does not work

even with help of stickmount. I have an App which uses data in /sdcard/HJNCE. While a directory Bind can

be established successfully with the above said scheme, "Directory Bind" app refused to save such a link(

source path=/data/media/0/usbStorage/sda1/HJNCE/ and target path= /data/media/0/HJNCE/), saying

"Enter valid target directory". After the target path was changed to /sdcard/HJNCE, the link was saved

and started in the app, but there was actually no bind between the two directories.

2. The "mount -o bind..." command may be put in a Tasker's task excuting at device boot.