Shared Work Space

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Revision as of 16:15, 22 November 2017 by Lwm14001 (talk | contribs) (BUG: updated default perms as they were incorrect for directories)
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Small Group File/Directory Sharing

Normal UNIX permissions managed through chown, and chmod, are extremely limited. One major limitation is that they do not allow you to provide access to just one other user, you have to provide access to a group of users, or all users. Since non-adminstrators cannot create UNIX groups, you cannot pass a file off one/more users without asking the HPC admin team to make you a group. File access control lists (facl's) solve this problem by allowing you to allow specific users/groups to access your files. The primary advantage to this is that you do not need to contact our support team to provide shared work space, and can instead create shared directories yourself.

To give one other user some permissions(same format as UNIX permissions) to access your file, you can do something akin to the following:

$ setfacl -m "u:user_name:permissions' example_file

To make your permission permeate to all new subdirectories and files you can set a default ACL for some directory.

$ setfacl -dm "u:user_name:permissions' example_dir

Properly set default ACLs, will be functionally equivalent to the shared work directories we can create for you. The advantage again being that you can make these shared work directories yourselves, with an added advantage that you can make any file or directory readable by just your colleagues. You can even make your home directory accessible.

To create a shared directory on our temporary file system you would do:

$ mkdir /scratch/shared_dir_name
$ setfacl  -m  "u:your_user_name:rwx" -m   "u:associate_1_user_name:rwx" -m   "u:associate_2_user_name:rwx" /scratch/shared_dir_name
$ setfacl -m "d:u:your_user_name:rwx" -m "d:u:associate_1_user_name:rwx" -m "d:u:associate_2_user_name:rwx" /scratch/shared_dir_name

You can add any number of "u:user_name:perm" fields to the above command while replacing the italicized areas appropriately.

To check some file or directories Access Control List you can do:

$ getfacl dir_or_file

For more information you can go to:

https://wiki.archlinux.org/index.php/Access_Control_Lists
http://vanemery.net/Linux/ACL/linux-acl.html#scenario

Large/Persistent Group Work

If you're in a large group, or your work requires persistent storage, you should open a ticket with Storrs HPC support, and we will evaluate if it necessary to provide disk space on /shared/, or /archive/.