The man page for filesys(5) under V7 says the total free blocks
field of the superblock is "not maintained by this version of the system."
That's probably why 2.8 bsd df has to count the number of free blocks.
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Phil Ngai (408) 988-7777 {ucbvax,decwrl,ihnp4,allegra,intelca}!amd70!phil