Allowing an external hard drive to be used by two users in Ubuntu 14.04
 

I am having an interesting issue:

I have 1 laptop and I made two user accounts for myself (ldm) and (a10).

I am using Ubuntu 14.04 which is running locally on the laptop.

The user called ldm is extracting data from an offsite location and saving the data to an external hard drive for space issues.

My second user, a10, must be able to access this data and display it with a software package I installed.

The data is stored therefore in /media/ldm/A10_2
(A10_2 is the name of the external)

However, when i log in as the A10 user rather than the ldm user and go to /media/ldm/A10_2, it won't let me view it due to permission issues.

Thus, I tried to do the following command:

chmod -R 777 /media/ldm/A10_2

This did not change the permissions

Then I tried to do

chown a10 A10_2

this did not change the owner.

I then tried to mount to the drive using the following command

mount --bind /media/a10 /media/ldm/A10_2

this mounted the location, but the a10 user could not see the data, but the ldm user could see both.

What I need is for both user accounts to be able to access this data saved and be able to rwx.

How can I do this?

Your command:

run with sudo permission would fix the issue, because it would allow 'others' to rwx.

I think more traditionally, you could use groups; there should be an 'ldm' group that got created when you created the 'ldm' user. Add a10 to this group with usermod or use System Settings > Users and Groups.

Then make sure that all the files on the drive are owned by the ldm user and the ldm group, and change the permissions to 770. a10 should be able to rwx through the group permission.