Re: grep-2.9.69-f91c on OSF/1

[Jim Meyering]

Stefano Lattarini wrote:
> On Saturday 12 November 2011, Jim Meyering wrote:
>> Stefano Lattarini wrote:
>> > This might cause annoying slow-downs on systems where forks are more
>> > expensive (i.e., MinGW and Cygwin).  What about doing something like
>> > this instead, so that the extra forks are avoided when the shell is
>> > Bash (as is the usual case under MinGW and Cygwin, if I'm not
>> > mistaken):
>> >
>> >   if test -n "$BASH_VERSION"; then
>> >     export_with_values () { export "$@"; }
>> >   else
>> >     export_with_values () { ... your implementation here ... }
>> >   fi
>> >
>> > My testing shows that this idiom should work with at least bash 4.1,
>> > 3.2, 3.0, 2.05 and 2.0.
>>
>> I like the idea but prefer to test for the precise feature being replaced.
>> Then we don't even penalize those who use dash or zsh.
>>
> Or you could do this, to shave off the extra fork on MinGW and Cygwin:
>
>> It is tricky, due to the brokenness of Solaris' /bin/sh, but as we
>> learned via init.sh, you have to eval the test in a sub-shell:
>>
>>     if (eval "export v=x") 2>/dev/null; then
>>       export_with_values () { export "$@"; }
>>     else
>>       export_with_values () { ... Bruno's implementation here ... }
>>     fi
>>
> Or you could do this, to shave off the extra fork on MinGW and Cygwin:
>
>     if test -n "$BASH_VERSION" || (eval "export v=x") 2>/dev/null; then
>       export_with_values () { export "$@"; }
>     else
>       export_with_values () { ... Bruno's implementation here ... }

Hi Stefano,

Thanks for the suggestion.
I was leaning towards accepting it, but then checked...

When /bin/sh is a link to bash, that envvar is not set here (F16):

    $ env -i sh -c env
    PWD=/h/j/w/co/grep
    SHLVL=1
    _=/bin/env
    $ ls -og /bin/sh
    lrwxrwxrwx. 1 4 Sep 29 04:19 /bin/sh -> bash

Is it set for MinGW or Cygwin?

Or is this expected to take effect solely when make is invoked
with SHELL=/bin/bash or similar?