afni.nimh.nih.gov

Thanks very much, that will be more convenient. In the mean time, I've been using the following check:

3dTrackID -mode DET ... <more arguments> \
  || { es=$?; [[ $es == 1 ]] && true || echo "3dTrackID exited with error code ${es}..."; }

This allows the script to keep rolling if it gets exit status 1, but it will be nice to remove that and have the script halt if there truly is an error.