From: John Stone (
Date: Wed Apr 22 2009 - 15:42:24 CDT

The "waitfor" command alters the way Tcl script command processing
proceedss. Normally, "mol new", "mol addfile", and "animate read" commands
all return immediately when told to load a trajectory. This allows scripts
to continue running while the trajectory continues asynchronously loading
in the background. This is a handy behavior for loading VMD saved states,
but when writing batch mode analysis scripts one typically prefers blocking
behavior rather than asynchronous behavior, and this is what you get with
"waitfor all". For the particular task you have in mind, you may wish to
use our "catdcd" program, as it can handle files that are larger than
physical memory, which is something that VMD doesn't (yet) support.

  John Stone

On Wed, Apr 22, 2009 at 01:36:00PM -0700, A D wrote:
> Hello,
> I have a question about the animate read and write commands. I wonder what exactly the waitfor option does and how the command flows through. It says in the manual "The waitfor option allows you to specify how many frames to load before returning." before returning... but to where?
> I am actually trying to read in frames from a large dcd file with a certain skip number and copy these frames to another dcd file.
> Thanks,
> Albert
> Biological Sciences Department
> University of Chicago

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