mdfil: Error unknown flag: /dev/null                                                                                                                                                                                                                                                       

     usage: sander  [-O|A] -i mdin -o mdout -p prmtop -c inpcrd -r restrt
                   [-ref refc -x mdcrd -v mdvel -e mden -frc mdfrc -idip inpdip -rdip rstdip -mdip mddip 
                   -ng numgroup -remlog rem.log -remtype rem.type -rem [0|1|2] -rremd [0|1|2|3] -saveene saveene 
                   -clusterinfo cluster.info -reservoir reserv/frame -hybridtraj hybrid.strip.crd
                   -inf mdinfo -radii radii -y inptraj -amd amd.log -scaledMD scaledMD.log] -cph-data <file>
Consult the manual for additional options.
[unset]: aborting job:
application called MPI_Abort(MPI_COMM_WORLD, 1) - process 0