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From: Richard Tobin <>
To: "Erik E. Fair" <>,
	The Eunuchs Hysterical Society <>
Subject: Re: [TUHS] Unix filesystem semantics history - files with holes
Date: Thu, 11 Apr 2019 16:57:48 +0100 (BST)
Message-ID: <> (raw)

> When did the Unix filesystem add the semantics for "files with holes" (large,
> sparse files)?

It was there in the first edition:

The FILE SYSTEM (V) man page includes a last paragraph identical to
that of FILSYS (V) in seventh edition:

  If block b in a file exists, it is not necessary that all blocks
  less than b exist.  A zero block number either in the address words
  of the the i-node or in an indirect block indicates that the
  corresponding block has never been allocated.  Such a missing block
  reads as if it contained all zero words.

The first edition indirect blocks were a bit different though: if the
file was bigger than 8 blocks (4kB), all the blocks in the inode were
(singly) indirect.

-- Richard

The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.

         reply index

Thread overview: 5+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-04-11  2:37 Erik E. Fair
2019-04-11  5:28 ` Ronald Natalie
2019-04-11 15:57 Richard Tobin [this message]
2019-04-11 19:09 ` William Corcoran
2019-04-11 19:49 ` Bakul Shah

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