File-Sharing.md

-File sharing may be as simple as an [automatic NFS link-tree such as the "/project" hierarchy](file-organization) maintained on the [RPWG](https://research-git.uiowa.edu/space-physics/doc/-/wikis/Legacy-Systems) legacy systems and now on the new [SPDR](SPDR) environment or as complicated as a DropBox-like service like [Nextcloud](https://nextcloud.com/) utilized by the Jaynes group.  Of course campus ITS provides a [number of options](https://its.uiowa.edu/storage-options-summary-chart) as well.
+File sharing may be as simple as an [automatic NFS link-tree such as the "/project" hierarchy](file-organization) maintained on the [SPDR](SPDR) environment or as complicated as a DropBox-like service like [Nextcloud](https://nextcloud.com/) utilized by the Jaynes group.  Of course campus ITS provides a [number of options](https://its.uiowa.edu/storage-options-summary-chart) as well.
 
-List options and solutions below.  Raise issues, questions, or meta-discussions in the "issues" link (is it a coffee cup or a stack of cards?) at the third icon down on the left.
+List options and solutions below.  Raise issues, questions, or meta-discussions in the "issues" link on the left.
+
+## Share Files with External Collaborators
+
+If you want to provide files to external collaborators (who don't have a hawkid), the easiest solution is to put them into a subdirectory of your `~/public_html` directory.  For example, given file
+
+```
+-rw-r--r-- 1 ljg clas_spacephysics_voyager 102274864 Jul 25 23:13 v1-p78910-despiked-spectrum1608-8.dat
+```
+which is clearly too big to send in email, I can
+```bash
+mkdir ~/public_html/voyager1
+cp -p v1-p78910-despiked-spectrum1608-8.dat ~/public_html/voyager1
+```
+then tell my collaborator to collect the file from
+```
+https://space.physics.uiowa.edu/~ljg/voyager1/v1-p78910-despiked-spectrum1608-8.dat
+```
+If the files should not be public, see @ljg for information on setting up simple username/password protection for specific web directories.
+
+If your remote collaborator has a need to upload files to our systems (because they don't have sufficient web services for you to pull the data from them), we have a couple of options.  One is an `sftp` service accessible via PKI (public/private keys) and the other is a novice-friendly web upload capability that is currently in development.  Ask @ljg for more information.
 
 ## [Windows Clients](Mounting-Project-Spaces)