[gmx-users] Basic question about command line

[Mohammad Madani]

Dear all
Hi,
I have a basic question about the using the gromacs.
I want to use gmx cluster for clustering. I use the cluster hpc.
When I run the this command:
gmx cluster -f *.trr -s *.gro -g *.log -clid *.xvg
I receive the error that I should select the group for least rmsd.
Could you please help me how can I add this part to the command line?
Can I do this??

Many thanks