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Re: Which behavior is expected of $(shell )
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From: |
Paul Smith |
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Subject: |
Re: Which behavior is expected of $(shell ) |
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Date: |
Mon, 21 Nov 2022 23:08:38 -0500 |
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User-agent: |
Evolution 3.46.1 (by Flathub.org) |
On Tue, 2022-11-22 at 11:12 +0800, Changqing Li wrote:
> Here is what the make manual says,
>
> 6.10 Variables from the Environment
It's not really related to this section. It's related to how the shell
function works. From that section of the manual we see:
| All variables that are marked as export will also be passed to the
| shell started by the shell function.
In your example, KBUILD_OUTPUT is coming from the environment, and all
variables imported from the environment automatically exported. So,
the value of the KBUILD_OUTPUT variable set in the makefile is exported
to the shell function.
However, this behavior is new in GNU make 4.4.
> the value in shell environment like what 4.3 done. But I don't find
> which commit or bug ID is for fixing this issue, so I send this mail
> to double check with the exports at this. Thanks a lot.
See this from the NEWS file for GNU make 4.4:
https://git.savannah.gnu.org/cgit/make.git/tree/NEWS?h=4.4&id=ed493f6c9116cc217b99c2cfa6a95f15803235a2#n74
> * WARNING: Backward-incompatibility!
> Previously makefile variables marked as export were not exported to commands
> started by the $(shell ...) function. Now, all exported variables are
> exported to $(shell ...).
This is the reason for the difference in behavior you see.