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From: ericblake AT comcast DOT net (Eric Blake)
To: cygwin AT cygwin DOT com
Subject: Re: base-files patch
Date: Fri, 25 Mar 2005 17:14:49 +0000
Message-Id: <032520051714.23741.4244470900087EF400005CBD22007340760A050E040D0C079D0A@comcast.net>

> On Fri, Mar 25, 2005 at 04:37:26PM +0000, Eric Blake wrote:
> I'm not sure I understand the removal of "``" for "portability" in the
> same patch which changes
> 
>   A=foo
>   export A
> 
> to
>   export A=foo

Yes, export A=foo is nonportable (/bin/sh, which is ash, does not like it, even though POSIX requires it), but since that line is inside the case that is doing shell-specific settings of PS1, it is guaranteed to only be executed by bash, which handles it.  By the way, is there a newer version of ash that is more POSIX-compliant?  The current version is more than a year old.

> 
> I've never seen a shell that didn't understand "``" but I have seen shells
> which didn't understand export A=foo.

It is not "``" alone, but "`""`" that has problems.  Some shells require the nested "" to be escaped with \, others don't, since some shells treat "`" as an error, and others can't parse "`\"\"`".  But since case does not do word splitting or filename expansion on its argument, and since `` is a quoting pattern and therefore forms the argument to case, (even if inside the `` contains spaces, or the command output has spaces), case `echo "$0"` is portable while case "`echo "$0"`" and case "`echo \"$0\"`" are not.  See the autoconf manual for more details.

> 
> Personally, I wish we wouldn't play any prompt games in the system profiles.
> I'd rather just either just have the standard prompt that the shell uses
> or my own customized version rather than assuming that we all know what
> the cygwin users want for a prompt.

True enough - how about having /etc/default/etc/profile always set PS1="$ ", then have /etc/profile/etc/skel/.bash_profile (and friends) set the colorized version that cygwin users have always had as their default.


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