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Behaviour of $(shell command args) is dangerously different from `comman
Vincent de Phily
Behaviour of $(shell command args) is dangerously different from `command args`
Wed, 10 Apr 2013 18:18:28 +0200
KMail/4.10.2 (Linux/3.7.9-hardened; KDE/4.10.2; x86_64; ; )
here's a Makefile distilled from an existing project (see attached file for a
> SHELL := /bin/bash
> date := $(shell date -R)
> prevtag := $(shell git describe --tags|cut -d- -f1)
> # sed -i "1s#^#$(VERSION) ($(date))\n$(shell git log HEAD...$(prevtag)
> # '--pretty=format:\\t* %s\\n'|tr -d '\n')\n#1" Changelog
> sed -i "1s#^#$(VERSION) ($(date))\n`git log HEAD...$(prevtag)
> '--pretty=format:\\t* %s\\n'|tr -d '\n'`\n#1" Changelog
What I am doing here is building a Changelog file using the output from git.
The problem is that with the first (commented) version of the command, if I
have a commit message containing something between backquotes, that something
gets executed by make. In my case I was lucky and just ran into an infinite
loop executing `make release`, but I would have been in bigger trouble if I
had a commit to, say, "Protect against unintentional `rm -rf /`."
Since I'm not a make guru, I'm not sure where this fits on the feature/bug
spectrum, but the fact that the behaviour differs from shell-style backquotes
(contrary to what "info:/make/Shell Function" leads me to believe) and the
dangerosity of it makes me feel it is a bug.
If the behaviour is expected (why ?), it would be usefull to explain the
difference between `command` and $(shell command) in the info pages.
I am using GNU Make 3.82 Built for x86_64-pc-linux-gnu from Gentoo packages.
Please CC me in replies, as I am not subscribed to the list.
Vincent de Phily
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- Behaviour of $(shell command args) is dangerously different from `command args`,
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