Re: builtin echo command redirection misbehaves in detached scripts when terminal is closed

[Stephane Chazelas]

On Sun, Sep 09, 2007 at 08:44:25PM +0200, Pierre-Philippe Coupard wrote:
[...]
> - akula, my bleeding edge box, is a Debian-unstable box upgraded yesterday 
> sept 8, 2007. It runs linux-2.6.17.7, libc6-2.6.1
>
> - kilo, my most up-to-date box where bash still seems to behave properly 
> with regard to that problem, is also a Debian-unstable box, upgraded on may 
> 1st, 2007. It runs linux2.6.18, libc6-2.5
>
> On both boxes, I tried Stephane's test line with bash-3.1.17 and 
> bash-2.05b:
>
> On both boxes, with bash-3.1.17, I get the "bash: line 0: echo: write 
> error: Broken pipe" message, and no error message with bash-2.05b.
>
> On akula, both versions of bash generate a file with 2 lines.
> On kilo, both version of bash generate a correct file with 1 line.
[...]

Would seem to be down to the version of glibc where the behavior
of fflush() would have changed. But I don't explain why Andreas
doesn't get the same behavior as me with the same version of
glibc.

I tried on a glibc 2.3.4 and with the C file I see only "b" in
the "a" file. Same thing with Solaris and HPUX with the system's
libc. So that would confirm that the behavior changed in the
glibc (probably somewhere after 2.5). And the problem may be
more of a glibc problem than a bash problem.

I've checked SUSv3 and it doesn't say wether the output buffer
should be emptied after a non-successful fflush() (as older
glibc seemed to be doing but as newer ones seem no longer to be
doing).

-- 
Stéphane