afni.nimh.nih.gov

I think that is common because "head -2" is closing the
stdout file stream while 3dhistog is still writing lots of
information, which crashes the program because it
does not check to see if the output stream is still open.

Almost any program that writes a lot to a file stream
could crash in such a way, e.g. try:

afni_proc.py -help | head

It is just an irritation, and is not something worth
coding around.

- rick