绘制到R中的文件

I'm a complete newbie to R, and none of the introductions I've seen cover how to use R when all you've got is the command line and no windowing system. My data's on a server, and I'm working with it via ssh. In gnuplot, you can set your "display" to be a PNG file on disk. How do I plot something to a file on disk from R? R-2.9.1 on CentOS, if it matters. Thanks!I'm a complete newbie to R, and none of the int