Hi,

I am trying to convert .nii file into .mgz file. However, I use this command:

 recon-all -i <dir/file.nii> -s <dir>

But I get the message: ERROR: ...exists, delete or re-run with -force.

So, I re-ran it with -force, and it worked. However, my question is:

- what exactly is the function of the force command?

And also I read somewhere in the presentations about FreeSurfer, that one has to be careful with nifti (.nii) files. But why do we have to be careful?

Thanks,

Carline