trb@floyd.UUCP (Andy Tannenbaum) (08/23/83)
According to the 4.1bsd (7th Edition) lseek(2) man page: Seeking far beyond the end of a file, then writing, creates a gap or `hole', which occupies no physical space and reads as zeros. Pray tell, just how far beyond EOF must one seek before this feature takes effect, and if not physical space, does it occupy some transcendental space? ;-) At least this man page tells you that the feature exists, the System III/V manuals just ignore it. Andy Tannenbaum Bell Labs Whippany, NJ (201) 386-6491
reha@orion.UUCP (R.GUR) (08/29/83)
Andy, This is in response to why the "gap" in files "feature" is documented in the 4.1BSD manuals and not the USG III and V manuals. I suspect that the 4.1 BSD manuals are descendents of the earlier V7 documents which had many details of the internal implementation of files within the kernel. I think that taking the implementation details (of files) out of the USG III and V manuals was a step in the right direction. Ordinary programmers using files on UNIX should not use details on how files are handled within the kernel. All that should be in the manual is that seeks beyond EOF are permitted. There should be a separate document entitled "The UNIX I/O System" or something like that to exhort the nitty gritty for "system programmers". orion!reha