Re: [PATCH] t5570: forward git-daemon messages in a different way

From: Johannes Sixt <j.sixt@viscovery.net>
Date: Apr 19, 2012, 06:58 UTC
Message-ID: <4F8FB779.60004@viscovery.net>
In-Reply-To: <20120419060326.GA13982@sigill.intra.peff.net>

Am 4/19/2012 8:03, schrieb Jeff King:

Show 12 quoted lines

> mkfifo fd
> yes >fd &
> pid=$!
> {
>         read line
>         echo $line
>         cat <fd &
> } <fd
> sleep 1
> kill $pid
> wait $pid
> rm -f fd

...

Show 11 quoted lines

> Hmm. Yeah, if you strace the cat, it gets an immediate EOF. And even
> weirder, I notice this in the strace output:
> 
>   clone(...)
>   close(0)                                = 0
>   open("/dev/null", O_RDONLY)             = 0
>   ...
>   execve("/bin/cat", ["cat"], [/* 50 vars */]) = 0
> 
> What? The shell is literally redirecting the cat process's stdin from
> /dev/null. I'm totally confused.

You don't have to be; it's mandated by POSIX:

http://pubs.opengroup.org/onlinepubs/9699919799/utilities/V3_chap02.html#tag_18_09_03_02

-- Hannes