On Wed, Dec 4, 2013 at 10:39 PM, Vladimir Marek
<[email protected]> wrote:
> Hi,
>
> What a coincidence, I just stumbled upon another issue. I don't have fix
> for this though ...
>
> The test script:
>
> $ cat c
> #!/bin/ksh
>
> trap 'exit' EXIT
>
> (
> yes | while read A; do
> echo "$A"
> STDERR=$(</dev/null)
> done
> )
>
> It should write infinite number of characters 'y'. But in reality it only
> writes one 'y' and ten empty lines only.
>
> Also if you run the script as
>
> $ ./c | head
>
> It hangs. I don't know whether the two things (not reading and hanging) are
> just a single issue or two different ones.
>
> I can reproduce this on both linux and solaris. On linux the ksh says
>
> $ echo $KSH_VERSION
> Version AJM 93u+ 2012-08-01
>
> On Solaris
> Version JM 93u 2011-02-08
>
> I'm just having a bad luck lately I guess ...
I can reproduce the same issue with the following reduced testcase on
Illumos B151a7/AMD64 with ast-ksh.2013-10-10/AMD64/64bit:
-- snip --
(
for ((;;)) ; do print y ; done | while read A; do
printf "%s\n" "$A"
STDERR=$(</dev/null)
done
)
-- snip --
It seems to be an issue with the non-|fork()|'ing subshell code... if
I force the code to use |fork()| for a subshell using the ulimit(1)
builtin I get the correct output:
-- snip --
$ cat c.sh
(
ulimit -c 0
for ((;;)) ; do print y ; done | while read A; do
printf "%s\n" "$A"
STDERR=$(</dev/null)
done
)
$ ~/bin/ksh c.sh | head
y
y
y
y
y
y
y
y
y
y
-- snip --
I can't reproduce the issue with piping the output to head(1) with
ast-ksh.2013-10-10 ...
----
Bye,
Roland
--
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