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* Re: dash drops exported bash functions
@ 2016-02-11  3:53 Makarius
  2016-02-11 12:15 ` Makarius
  0 siblings, 1 reply; 9+ messages in thread
From: Makarius @ 2016-02-11  3:53 UTC (permalink / raw)
  To: dash

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On 02/10/2016 08:54:40 Eric Blake wrote:

> That said, preserving any unusable environment variables unchanged,
> rather than scrubbing them, may be slightly nicer behavior, but I'm not
> sure it's worth the bloat to dash to do so.

> > Exporting bash functions via the environment might be a rarely used 
> > feature, but it is used in practice, unfortunately (otherwise I 
> > wouldn’t have noticed this).
>
> Exporting bash functions is only usable if you plan on directly invoking 
> bash.  Don't drag dash into the mess.  Inserting a dash child in between 
> a bash parent and grandchild means all bets are off for whether the 
> grandparent can export anything to the grandchild.

Eric,

I am a long-term user of GNU bash who is depending on the "export -f" 
feature of that shell (in an application that is on the free market for 
decades). The bash guys turn a shell function "foo" into the environment 
variable "BASH_FUNC_foo%%" and hope to be able to pick it up later on.

Dash gets into this game, because Ubuntu and Debian have chosen to make it 
the default for /bin/sh some years ago. This means that typical "system" 
invocations of Unix tools and libraries are now going through dash: 
/bin/sh -c is often seen in practice instead of more delicate execve 
invocations.

This means with /bin/sh -> dash users have no proper chance to avoid it. 
Sitting right there in the center /bin/sh, dash acquires special 
responsibilities to play nice with other shells.


Note that the issue has come up now due to this recent change in 
Debian-testing: https://tracker.debian.org/news/744916

Thus a the following change from 2012 became exposed to testers/users of 
Debian: 
http://git.kernel.org/cgit/utils/dash/dash.git/commit/?id=46d3c1a614f11f0d40a7e73376359618ff07abcd

In that change 46d3c1a614f, the original motivation was to make "export 
-p" work more robustly in dash, and not to cripple export -f in bash 
because of POSIX violations.


 	Makarius

^ permalink raw reply	[flat|nested] 9+ messages in thread
* dash drops exported bash functions
@ 2016-02-10 15:18 Joachim Breitner
  2016-02-10 15:54 ` Eric Blake
  0 siblings, 1 reply; 9+ messages in thread
From: Joachim Breitner @ 2016-02-10 15:18 UTC (permalink / raw)
  To: dash


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Dear dash developers,

a change in 0.5.8, very likely this one
http://git.kernel.org/cgit/utils/dash/dash.git/commit/?id=46d3c1a614f11f0d40a7e73376359618ff07abcd
broke the exporting of bash shell functions via the environment.

The attached script shows the breakage, as it outputs

$ ./exporttest.sh 
exportest called ()
Setting up environment
Calling myself
exportest called (1)
function foo successfully called
Calling myself directly
exportest called (2)
function foo successfully called
Calling myself via dash
exportest called (3)
/tmp/exporttest.sh: Zeile 33: foo: Kommando nicht gefunden.
Done

Exporting bash functions via the environment might be a rarely used
feature, but it is used in practice, unfortunately (otherwise I
wouldn’t have noticed this).

Thanks,
Joachim

-- 
Joachim “nomeata” Breitner
  mail@joachim-breitner.de • https://www.joachim-breitner.de/
  XMPP: nomeata@joachim-breitner.de • OpenPGP-Key: 0xF0FBF51F
  Debian Developer: nomeata@debian.org


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^ permalink raw reply	[flat|nested] 9+ messages in thread

end of thread, other threads:[~2016-02-11 14:46 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2016-02-11  3:53 dash drops exported bash functions Makarius
2016-02-11 12:15 ` Makarius
2016-02-11 13:40   ` Makarius
2016-02-11 14:19     ` Olof Johansson
2016-02-11 14:30       ` Makarius
2016-02-11 14:46         ` Stephane Chazelas
  -- strict thread matches above, loose matches on Subject: below --
2016-02-10 15:18 Joachim Breitner
2016-02-10 15:54 ` Eric Blake
2016-02-10 16:31   ` Joachim Breitner

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