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Re: a patch to fix sh_stat on SunOS

From: Dmitry Goncharov
Subject: Re: a patch to fix sh_stat on SunOS
Date: Sun, 21 Aug 2016 22:36:37 -0400
User-agent: Mutt/1.5.21 (2010-09-15)

On Sun, Aug 21, 2016 at 03:04:07PM -0400, Chet Ramey wrote:
> The current text in redirection says:
> Bash handles several filenames specially when they are used in redirec-
>        tions, as described in the following table.  If the operating system on
>        which bash is running provides these special files, bash will use them;
>        otherwise it will emulate them internally with the  behavior  described
>        below.
> The text for conditional expressions should say something similar.

Got it.

> No.  If the OS provides /dev/fd and bash can detect it at build time,
> process substitution, redirection, and conditional expressions will all
> simply use the files the OS provides.  There is no asymmetry.

You are right.

> > With this new contract how can the user write portable bash code which 
> > tests if
> > a fd refers to a pipe?
> It's hard to say, given the existence of multiple incompatible
> implementations of /dev/fd.  It looks like SunOS is the oddball here,
> but there might be other implementations that don't do the same thing
> with stat(2).
> But why should bash override the semantics that an OS provides for
> /dev/fd, resulting in differing behavior between the shell and other
> utilities with the same pathname argument?

For the benefit of the user. Currently bash behavior is different from the
native test and ksh on sunos.
What about a patch that switches to fstat only if such /dev/fd oddity was
determined at configuration time?

regards, Dmitry

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