Newsgroups: comp.unix.internals
Path: utzoo!utgpu!cunews!micor!latour!mcr
From: mcr@Latour.Sandelman.OCUnix.On.Ca (Michael Richardson)
Subject: Re: anonymous ftp ?
Message-ID: <1990Dec29.015430.9108@Latour.Sandelman.OCUnix.On.Ca>
Organization: Sandelman Software Works, Debugging Department, Ottawa, ON
References: <2379@bnlux0.bnl.gov> <1990Dec28.173122.6421@athena.mit.edu>
Date: Sat, 29 Dec 90 01:54:30 GMT

In article <1990Dec28.173122.6421@athena.mit.edu> jik@athena.mit.edu (Jonathan I. Kamens) writes:
>  I seem to recall that /dev/zero is Sun's version of /dev/null.  If you
>create ~ftp/dev and create a "zero" device in it with the same major and minor
>device numbers as the /dev/zero in your root filesystem, this problem should
>go away.

  /dev/zero is just like /dev/null, except that you can read an
infinite number of zeros from it (rather than 0 'infinites' :-)
  It is probably used with a mmap call to get some mapped memory or
something...

  'man zero' tells me:

 "   Mapping a  zero  special  file  creates  a  zero-initialized
     unnamed memory object of a length equal to the length of the
     mapping and rounded up to the nearest page size as  returned
     by getpagesize(2).  Multiple processes can share such a zero
     special file object provided a common  ancestor  mapped  the
     object MAP_SHARED.  "

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