From: Ashar Malik (
Date: Mon May 27 2019 - 09:48:23 CDT

I usually do something like this.

make a selection of everything (you want chain IDs for).

   - set sel_all [atomselect top all]

get chain IDs

   - set chain [$sel_all get chain]
   - set chain_u [lsort -unique -dict $chain]

the variable $chain_u should now contain a list of chains in your system

On Mon, May 27, 2019 at 7:22 PM MD Simulation <>

> Hello,
> I'm having some trouble figuring out how to get the number of fragments in
> a TCL script. Is this some mol or molinfo can handle?
> Thanks for the help!
> Stacey