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From: eric@brolga.cc.uq.oz.au (Eric Halil)
Newsgroups: comp.unix.shell
Subject: How does the ksh ENV "trick" work?
Message-ID: <1991May27.054451.24232@brolga.cc.uq.oz.au>
Date: 27 May 91 05:44:51 GMT
Organization: Prentice Computer Centre, The University of Queensland, Australia.
Lines: 12

In "The Kornshell Command and Programming Language" by Morris I. Bolsky and
David G. Korn, Prentice-Hall, 1989, ISBN 0-13-516972-0, page 78 they give:

  export FILE=$HOME/.kshrc
  # The subscript below evaluates to 0 when interactive.
  ENV='${FILE[(_$-=0)+(_=1)-_${-%%*i*}]}'

as a easy way to stop your .kshrc being evaluated when it's an not an
interactive shell.  Can someone explain in detail how this works? 

Thanks,
Eric (eric@cc.uq.oz.au)