Path: utzoo!attcan!uunet!husc6!mailrus!tut.cis.ohio-state.edu!osu-cis!att!ihnp4!skep2!wcs
From: wcs@skep2.ATT.COM (Bill.Stewart.<ho95c>)
Newsgroups: comp.sources.bugs
Subject: Re: Jove bug
Message-ID: <108@skep2.ATT.COM>
Date: 16 May 88 22:45:55 GMT
References: <321@syntron.UUCP> <4071@killer.UUCP>
Reply-To: wcs@skep2.UUCP (46323-Bill.Stewart.<ho95c>,2G218,x0705,)
Organization: AT&T Bell Labs Center 4632, Holmdel, NJ
Lines: 34

[ Summary of the bug - if the PWD variable is present, Jove 4.9 assumes
[ that ksh is keeping it up to date, and uses it instead of getcwd().  
[ This is a problem if you aren't using ksh, but have PWD in your
[ environment from a parent process, because it's presumably wrong.

In article <4071@killer.UUCP> elg@killer.UUCP (Eric Green) writes:
} I "solved" the problem simply by commenting out the getenv("CWD") and
} getenv("PWD") calls, and falling through into the getcwd() call.  But
} that's no permanent solution.  [..]
} It's not a bug in csh. csh doesn't need fixing (though Sys V does :-).  csh
} isn't supposed to maintain the "PWD" environment variable.  If csh was my
} login shell, that would be no problem -- there would be no "PWD" environment
} variable, and Jove would fall through into the getcwd().

If you think ksh maintaining $PWD is a bug, better excise $cwd from csh :-).

As a workaround, in your .login (if applicable) or .cshrc, do
	unsetenv PWD
	setenv SHELL=/bin/csh	## whatever the syntax is?

The general problem is how to detect when an environment variable has
a reliable meaning - at minimum, you should only use $PWD if it's non-null
and $SHELL is ksh, but even that's unreliable.  Better to just let Jove getcwd().

In a shell script, you can distinguish between 
Bourne sh and ksh reliably by checking
	if [ "$RANDOM" = "$RANDOM" ]
but that's no help from an executable.

-- 
#				Thanks;
# Bill Stewart, AT&T Bell Labs 2G218, Holmdel NJ 1-201-949-0705 ihnp4!ho95c!wcs
# skep2 is a local machine I'm trying to turn into a server.  Please send
# mail to ho95c or ho95e instead.  Thanks.