Path: utzoo!utgpu!watserv1!watmath!att!pacbell!pacbell.com!ames!ucsd!usc!sdd.hp.com!hp-pcd!hpfcso!hpfcdc!pbm
From: pbm@hpfcdc.HP.COM (Peter McLain)
Newsgroups: comp.sys.apollo
Subject: Re: Korn shell, mailing lists
Message-ID: <8570002@hpfcdc.HP.COM>
Date: 9 Jul 90 23:32:04 GMT
References: <9007061658.AA23939@fermat.Mayo.edu>
Organization: HP Ft. Collins, Co.
Lines: 47


>I am starting to write korn shell scripts.  I would like to disable the
>execution of the file pointed to by the ENV parameter when entering the
>script.  How is this done?

    You can turn off the processing of the ENV file for non-interactive
    shells with the following in your ~/.profile:

		export ENV='${FILE[(_$-=1)+(_=0)-(_$-!=_${-%%*i*})]}'
		export FILE=$HOME/.envfile

    The idea is that ${FILE[0]} = "$HOME/.envfile" and ${FILE[1]} = "".
    ENV evaluates to the former for interactive shells and the latter
    for non-interactive shells.  The parameter "-" will contain an 'i'
    for an interactive shell (try "echo $-" in a shell script and at the
    prompt).  All the work is done in the subscript to FILE in the 
    first line above:

	(_$-=1)               set parameter named _$- to 1 (e.g.,
                              set _ism=1 for an interactive shell and
                              set _h=1 for a non-interactive shell).

	(_=0)                 set parameter named _ to 0 (we need this
                              since we may reference $_ in the next step).

	(_$-!=_${-%%*i*})     "${-%%*i*}" evaluates to "" if $- contains
                              an 'i', and to $- otherwise.  For an interactive
                              shell the check is if "_$-" is NOT the same as
                              "_$-" (false) and for a non-interactive shell the
                              check is if "_$-" is not the same as "_" (true).
                              So this evaluates to 1 (false) for interactive
                              shells, and 0 (true) for non-interactive shells.


    So for interactive shells you get:

	${FILE[1+0-1]} = ${FILE[0]} = $HOME/.envfile

    and for non-interactive shells you get:

	${FILE[1+0-0]} = ${FILE[1]} = ""

---------------------
Peter McLain                                          Hewlett-Packard
                                                      3404 East Harmony Road
pbm%hpfclg@hplabs.HP.COM                              Fort Collins
UUCP: hplabs!hpfcla!pbm                               CO          80525-9599