[Adding bug-autoconf]
On 06/27/2012 12:40 AM, Jonathan Nieder wrote:
> Hi,
>
> Quick first impressions:
>
> Anders Kaseorg wrote:
>
>> Sidestep this problem by opening the backflow FIFO once for
>> read+write.
>
> Is that portable?
>
According to the Autoconf manual, no:
Some shells, like ash, don't recognize bi-directional redirection (‘<>’).
And even on shells that recognize it, it is not portable to use on fifos:
Posix does not require read-write support for named pipes, and Cygwin
does not support it:
$ mkfifo fifo
$ exec 5<>fifo
$ echo hi >&5
bash: echo: write error: Communication error on send
But while the issue about Cygwin might still be relevant, the one about
ash seems to be out-of-date: I've verified that the "exec 5<>fifo"
command works with both dash 0.5.2 and dash 0.5.5.1 (that's why I'm
CC:ing bug-autoconf).
Regards,
Stefano
