The brief answer is that no, it is not doable from the command line unless all you want is the highest-probability rotamer (and if that's the case read the links that Elaine sent for how to do that). It is possible using the GUI. It is also possible using Python code (almost anything is). If you know how to program Python, look at the useRotamer() function in Rotamers/__init__.py [in the Chimera distribution] to get started.I am working in the development of a program that I need the possible rotameros (of one the 5 possible rotamers) for a set of amino acids and I would like to know as chimera can make this using the command line.