Hi Galit,
When run with -acf of -ACF, 3dFWHMx will write out the fit and measured ACF parameters to a text file. If you do not specify one, it will write to 3dFWHMx.1D. Since this will generally be executed per run, to overwrite the existing file from a previous run, it just whines about it. If you never look at these files, you probably do not care.
When using afni_proc.py to do this, it specifies an output file name for each run, so that they do not try to overwrite.
- rick
