Question about bi-directional pipes.
I was just wondering if it is possible under Linux to use popen in a bi-directional way? I want to use popen under php and must write _and_ read from and to the pipe. Some guy at the php mailing list stated that this is possible to do with BSD, he wasn't sure about linux.
If this is a kernel issue and not a glibc one, is there a way to get popen work bi-directionally under linux? Say I want a
pipe = popen ('somefile', 'w+');
return a valid pipe. As it is now, popen (at least under php, but I think this should be the same), does not return a handle for mode 'w+'. It does return a handle only for modes 'r' and 'w'.
Regards,
;Martin
Signature · 12 lines
Dipl.-Kfm. Martin Rode [email protected] Programmfabrik GmbH Frankfurter Allee 73d 10247 Berlin http://www.programmfabrik.de/ Fon +49-(0)30-4281-8001 Fax +49-(0)30-4281-8008 Funk +49-(0)163-5321400
On Tue, Jan 08, 2002 at 09:47:06AM +0100, Martin Rode wrote:
I was just wondering if it is possible under Linux to use popen in a bi-directional way?
using pipe(2) --- no
I want to use popen under php and must write _and_ read from and to the pipe. Some guy at the php mailing list stated that this is possible to do with BSD, he wasn't sure about linux.
Some (all) of the *BSD's implement pipe(2) using UNIX domain sockets under the hood and were thus able to do this, however, I don't believe any other OS ever did this and I certainly wouldn't assume it will work for compatibility reasons.
If this is a kernel issue and not a glibc one, is there a way to get popen work bi-directionally under linux? Say I want a
pipe = popen ('somefile', 'w+');
Don't use glibc for this, it can't do what you want. I have a small library I wrote that does a popen type thing and gives separate access to stdin, stdout and stderr of the process --- if that is of use you are welcome to it (it's C, not php, I have no idea about how to import C functions into php).
With a (small) amount of effort, I can even make a version that nukes stderr and wraps the stdin/stdout functions with a a UNIX domain socket which will do pretty much exactly what you want[1].
--cw
[1] Oh, it doesn't do command-line parsing as I explicitly didn't want this when I wrote it.