Hi All, Here's my problem: I need to calculate hydrogen bonds for several thousand PDB files. Chimera has nice hbonds command line command - sweet! Since Chimera was vanishing from Ubuntu, I had to switch to other available tools, i.e. Windows. After I got my python up and running and communicating with Chimera modules. Here's my very simple pseudo-idea: foreach file in the list: open PDB file construct output filename from input filename calculate & and write out hydrogen bonds using hbonds command close file end foreach Short and sweet. Except that one cannot use a command line command within python code. Command files don't work either because they do not understand python commands. Someone must have run into the same problem before me :-) Is there a way around this problem? Thank you, Svetlana