ENV file in ksh: is this smart? legal?

[Stephen Vinoski]

In article <716 at rodan.acs.syr.edu> jdpeek at rodan.acs.syr.edu (Jerry Peek) writes:
>#2.  The next problem I have with ENV files -- if their name is stored
>in the environment (export ENV) -- is that Korn shell script files
>(shell programs) read them too.  I have some stuff in my ENV file that
>screws up shell scripts.
>
>Here's how I fixed the problem.  I put this at the start of my ENV file:
>	case "$-" in
>	*i*) ;;	# IF SHELL IS INTERACTIVE, READ THIS FILE
>	*) return ;; # ELSE, EXIT AND DON'T READ IT
>	esac

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

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

This way ENV expands to null when the shell is not interactive.  I use this and
it works perfectly.

I also highly recommend the book - it's a great reference with some really good
examples of the power of the Kornshell.


-steve
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