ess-via-tramp.Rmd

---
categories: 
- tutorials
date: "2021-01-06"
tags: 
- emacs
- programming
- bioinformatics
- R
- remote
title: "Getting Started with R Programming in Emacs: working on a remote server"
slug: emacs-tutorial-remote
author: "Chris Wallace"
---

It can be slow and frustrating to run R via a GUI when your data and R are on a remote server.  Emacs has long had support for editing remote files via [tramp](https://www.gnu.org/software/tramp/), and ESS allows emacs to interact with a remote R process.  This can bring the best of both worlds: a GUI editor running locally (so fast), interacting with an R process on the remote server.  Graphics can be served from the remote server as long as you have lines like 

```
Host *
     ForwardX11 yes
```

in your ssh config file (`~/.ssh/config` on a linux machine).

In this doc, I assume
- emacs is installed on the  local machine `A` 
- R is installed on the  remote  server `B`
- you know how to ssh from `A` to `B`
- you have installed ESS as described in [intro to ESS](https://github.com/ess-intro/presentation-ess-base-install)
Your R script files can be on either `A` or `B`.

# Starting a remote R process within emacs

First open a file or directory on the remote server over ssh. 

`C-x C-f /ssh:user@B:~/ RET`

If you have aliases set up in your `$HOME/.ssh/config` you can use the alias here instead of `user@B`.  Then if you start an R process from that buffer, it will call R on the machine `B`.  Do this by 

`M-x R`

That's it, you have a running R process on the remote machine.  Type

`system("hostname")`

to check.

# Interacting with a remote R process from an R script on a remote server

Open the remote R script over ssh. E.g. if the script is called myscript.R in your remote home directory, do 

`C-x C-f /ssh:user@B:~/myscript.R RET`

Start an R process from that buffer, it will split the window if needed, and start on the machine `B`.  Do this by 

`M-x R`

That's it, you should have a running R process on the remote machine.  All the standard ESS commands should work.  So if you type a line in the script file, you can run it in the R process using 

`C-c RET`

or run a block of code using 

`C-c C-c`

See the [intro to ESS](https://github.com/ess-intro/presentation-ess-base-install) to learn more.

# Configuring tramp

While tramp comes with emacs, there are a couple of settings that can help if you add them to your emacs config file

```
;; ssh seems the most reliable connection method
(setq tramp-default-method "ssh") 
;; this sets the path on the remote server according to the ~/.profile file on the remote machine. Useful if your R is in a non-standard location
(add-to-list 'tramp-remote-path 'tramp-own-remote-path)) 
```