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Re: bash 4.x filters out environmental variables containing a dot in the

From: Stephane CHAZELAS
Subject: Re: bash 4.x filters out environmental variables containing a dot in the name
Date: Sat, 27 Jun 2009 08:08:36 +0000 (UTC)
User-agent: slrn/pre1.0.0-11 (Linux)

2009-06-26, 13:58(+02), Christian Krause:
> Hi Chet,
> Thanks for the answers. The problem is now, that this behavior of the
> bash creates some real problems outside, probably with a larger impact.
> Before asking the kernel developers to change parts of linux kernel's
> build system, I'd like to be sure whether bash-4.x's behavior is correct
> or not. Please see my comments below:

POSIX doesn't prevent bash to do so I suppose, and bash is not
the only shell to do so, pdksh based shells (which many systems
sh are based on) also do so.

bash3 and ksh93 also strip some environment variables (and
override others like IFS)

bash3 strips the environment strings that have no = in them, and
the environment variable with an empty name.

ksh93 also strips the environment strings without "=" except the
empty string.

Now, I can't think of any good reason why shells would do things
like that (removes things from the environment which they have
no business with) and it seems wrong to me as well, but one
shouldn't rely on shells preserving environment variables that
can't be mapped to shell variables as in practice that's no the
case for a few shells, and it seems it's unspecified by POSIX.


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