Use a default path in exec*p*() if PATH is unset?
Tue Apr 11 11:11:00 GMT 2017
Thomas Wolff wrote:
> Am 10.04.2017 um 22:29 schrieb Christian Franke:
>> A few years after https://cygwin.com/ml/cygwin/2014-09/msg00204.html
>> I found another use case of an unset PATH variable:
>> The configure script from mandoc (http://mdocml.bsd.lv/) uses this
>> interesting approach to query default CC command from make:
>> CC=`printf "all:\\n\\t@echo \\\$(CC)\\n" | env -i make -sf -`
> Why does it `env -i` at all?
I guess because make result should not depend on environment. I agree
that 'env -i' is probably to much, 'env -u CC' would be enough.
> (And why does it prepend a \ to the output?)
It doesn't. The extra \\ is required because `...` is used instead of
$ printf "all:\\n\\t@echo \\\$(CC)\\n"
$ CC=$(printf "all:\\n\\t@echo \\\$(CC)\\n" > /dev/tty)
$ CC=`printf "all:\\n\\t@echo \\\$(CC)\\n" > /dev/tty`
> It seems this scriptlet has an issue, rather than adapting core
> behaviour for it.
Of course Cygwin shouldn't be adapted solely for this single case.
But it possibly Cygwin should be adapted to the existing practice of
various other open source *ix systems.
Interestingly the approach in newlib/libc/posix/execvp.c differs from
Cygwin and others:
execvp() with PATH unset calls execv(). This has the same effect as
execvp() with PATH set to current directory only.
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