#rev 2020-09-07 bonaccos

= How can I give several users write access to a directory =

In general please do use a project group accordingly and follow [[Services/ProjectData|Data Sharing instruction]].


A quick-and-dirty instruction on how to acomplish sharing of data on a filesystem which understands POSIX ACLs follows.

This trick can be performed with the commands `setfacl` and `getfacl` (ACL means Access Control List) when the filesystem supports POSIX ACLs. They both have a manpage. Since the concepts of using them is not that simple, you might want to look at the following example.

User `tanja` wants to setup a directory `/scratch/community` which she and her friend `andrea` can access but which is closed to all other users.

She creates a file `myacls` with the content:

{{{
# basic permissions for /scratch/community
user::rwx               # the owner of the directory has read write execute access
group::---              # group has no access
other:---               # neither has all the rest of the world
# acl for ~/community
user:tanja:rwx          # the same for tanja
user:andrea:rwx         # and andrea
mask:rwx                # the highest access privilidge one can get is read write execute
# when new files are created within /scratch/community, they get the following acl
default:user::rwx       # the owner of the new file has read/write/execute access
default:user:tanja:rwx  # tanja will have read/write/execute access to all the new files
default:user:andrea:rwx # and so does andrea
default:group::---      # the group has no access
default:mask:rwx        # the highest access will be read/write/execute
default:other:---        # others have no access
}}}
Now she executes `setfacl -R --set-file=myacls /scratch/community` to apply the new permissions to `/scratch/community`. With `getfacl /scratch/community` she can check that everything worked fine.

Please note that the quota rules still do apply here.

In addition, the `default` entries only apply on directories, for files there are no default ACLs.

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[[CategoryLXBS]]