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X-Authentication-Warning: slinky.cs.nyu.edu: pechtcha owned process doing -bs
Date: Thu, 1 Apr 2004 15:37:27 -0500 (EST)
From: Igor Pechtchanski <pechtcha AT cs DOT nyu DOT edu>
Reply-To: cygwin AT cygwin DOT com
To: Volker Quetschke <quetschke AT scytek DOT de>
cc: cygwin AT cygwin DOT com
Subject: Re: Is !C: a valid environment variable?
In-Reply-To: <406C6B13.3070401@scytek.de>
Message-ID: <Pine.GSO.4.56.0404011526310.29906@slinky.cs.nyu.edu>
References: <406C6B13 DOT 3070401 AT scytek DOT de>
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On Thu, 1 Apr 2004, Volker Quetschke wrote:

> Hi!
>
> If you start bash from a command prompt, e.g. by starting the
> cygwin.bat you get funny environment variables:
>
> bash-2.05b$ set | grep \!
> !C:='C:\cygwin\bin'
>
> When you exit bash and start it again from the same shell you can
> even get:
>
> bash-2.05b$ set | grep \!
> !C:='C:\cygwin\bin'
> !EXITCODE=00000000
>
> But try to echo any of these, or define one with !.
>
> bash-2.05b$ export !HELLO=hello
> bash: !HELLO=hello: event not found

'!' is a bash special character.  For a more meaningful error message, try
"export \!HELLO=hello".  However, I don't believe bash allows variable
names containing '!'...

> I think this special treatment is a bug, what is the prefered solution?

POSIX, however, does allow these names, i.e., the first argument to
putenv() can be an arbitrary string (containing everyting but '\0' and
'=', IIRC).

> The special treatment is done in environ.cc:
>
>    /* Current directory information is recorded as variables of the
>       form "=X:=X:\foo\bar; these must be changed into something legal
>       (we could just ignore them but maybe an application will
>       eventually want to use them).  */
>
> I'm asking because I have a programm that chokes on !<something>
> environment variables, and he workaround I'm using is always starting
> the shell via: C:\cygwin\bin\rxvt.exe -e /usr/bin/bash --login -i
> from the desktop or logoing into that machine via ssh.
>
> Volker

Another way of doing this is "env -i /bin/bash --login -i",
or, if you just want to unset the troublesome ones,
"env `set | sed -ne '/\!/{s/=.*$//; s/^/-u / p}'` bash --login -i".

HTH,
	Igor
-- 
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