Why Do It?

If you quickly want to change a little code and then run it on the robot, it’s nice to have a file shared between your development pc and the ev3dev robot. That’s what this tutorial accomplishes with NFS. It’s also a fast and easy way to tune parameters or access log files.

This requires editing some config files and getting addresses and filenames straight. For more advanced users.

The NFS protocol is the standard Linux way to share files between computers, and since you’re running Linux on the EV3, and there’s nfs support built-in, you can share files between your computer and the EV3.

More uses for a shared folder:

screenshot

The instructions here are for all three platforms Linux, Windows, and OSX - just pick the one you need

How To Do It - Linux

On your Linux box, you’ll need to edit a file called /etc/exports. If you don’t have this file, then you need to install nfs-common or a similar package.

Open the file and add the following line:

/home/youruserid/nfs/ev3dev   192.168.254.*(rw,sync,no_subtree_check,root_squash)

All you need to do is tell nfs which directory you want to share (/home/youruserid/nfs/ev3dev) and who you want to share it with (192.168.254.*).

Note that 192.168.254.* is my personal wifi subnet. For those of you that are trying to set up nfs over USB Ethernet, the default subnet that ev3dev expects is 192.168.2.*.

The options, enclosed in parenthesis, tell nfs to:

So update the file on your host machine, then run sudo exportfs -rv which will update the directories that nfs exports.

Now update the fstab on the EV3 (see below).

How To Do It - Windows

Download and Extract WinNFSd. You will have a folder with an executable, license, and readme file. Open notepad, and enter this line.

winnfsd.exe -id 0 0 -log off [directory]

Where [directory] is the full path to the folder as it shows in the file explorer. For example, mine is

winnfsd.exe -id 0 0 -log off E:\Users\James\Dropbox\ev3dev

Save it as all files, name it launch.bat

Now launch launch.bat and the server is running.

Time to update the fstab on the EV3 (see below).

How To Do It - OS X

Setting up an NFS share on a Mac running 10.5 (Leopard) or later is very similar to setting it up in Linux.

On your Mac, simply edit (or create) the /etc/exports file (as root), adding a line for each path on your Mac that you wish to share. Here’s a simple example:

#/etc/exports
/path/to/shared/folder                    -network 192.168.0.0 -mask 255.255.0.0
/path/to/read_only/shared/folder -ro      -network 192.168.0.0 -mask 255.255.0.0
/path/to/shared/tree             -alldirs -network 192.168.0.0 -mask 255.255.0.0

The -network and -mask options limit access to the shared directory to those on the 192.168 subnet. The -ro option limits access to read-only, while the -alldirs option provides access to all subdirectories of the specified path.

For this example, I’m going to share the Public folder under my userid (of course your userid will be different) and the subnet will be 192.168.2.0 for the case of the USB over Ethernet connection.

#/etc/exports
/Users/youruserid/Public -maproot=root:wheel -network 192.168.2.0 -mask 255.255.255.0

Wait, what’s that goofy -maproot=root:wheel doing there? Well, it’s the little hint that Barry has on his page that maps the nfs client’s root user to the root user on the OSX host, and it also maps the root group to the OSX wheel group. Because BSD has to be, you know, different!

After creating the file, the nfsd daemon should automatically start up. If necessary it can be enabled permanently using nfsd enable. You can check to see if it’s working with showmount -e, which will give you a list of the active NFS shares, like this:

Exports list on localhost:
/Users/youruserid/Public                     192.168.2.0

If you make changes to /etc/exports, activate them with nfsd update.

Now update the fstab on the EV3.

How To Do It - EV3

On the EV3 we first need to enable and start NFS modules. Type these commands on the command line:

systemctl enable nfs-common.service
systemctl start nfs-common.service
systemctl enable rpcbind.service
systemctl start rpcbind.service

Next you’ll need to update a file (as root) called /etc/fstab. You should have already set up USB Networking, so ssh to the EV3 and run an editor like vi or nano to edit the file. Here’s the line you want to add to /etc/fstab - DO NOT TOUCH ANYTHING ELSE IN THERE!

# NOTE - the following examples all use the same IP address for the host, in practice, there would
#        be separate addresses for each host!

# For the Linux example, it would look like:
192.168.2.1:/home/hostuserid/nfs/ev3dev /home/robot/nfs/linux   nfs users,noauto,rw,vers=3  0 0

# For the Windows Hanewin example, it would look like:
192.168.0.199:\E\Users\James\Dropbox\ev3dev                       /home/robot/nfs/windows nfs users,noauto,rw,vers=3  0 0

# For the OSX example, it would look like:
192.168.2.1:/Users/youruserid/Public    /home/robot/nfs/osx     nfs users,noauto,rw,vers=3  0 0

It’s not too hard to figure out what’s going on here. The host machine with the nfs mount is at 192.168.2.1 and we added /home/hostuserid/nfs/ev3dev (or whatever the host is exporting the directory as) to the /etc/exports file on that machine. The next section of the line says we want to mount it locally at /home/ev3userid/nfs/linux, or whatever directory you choose.

The options tell mount that:

Once you’ve updated the /etc/fstab file, you will need to create the mount points. Since I test ev3dev o n all three major platforms, I have separate directories for each nfs host. You probably only need to create one of these, but this script creates all three for me:

mkdir -p ~/nfs/linux
mkdir -p ~/nfs/windows
mkdir -p ~/nfs/osx

Then all you need to do is mount the share, like this:

mount ~/nfs/linux

…or whichever of the above three directories you want to mount.

And then you should be able to see the files on your host computer when you do ls /home/ev3userid/nfs/ev3dev!

References

Authors



JNFitzgerald