Re: Sockets as filenames.

Ian Stirling wrote:

> Or absolutely ideally, for all files in
> awk -f whatever.awk /inet/tcp/... /inet/tcp/... /home/me/file

Now I see what your problem actually was.
/inet/tcp has a meaning inside GNU Awk;
outside (in the realm of any shell) it
has no meaning. But even inside GNU Awk
sockets must be handled differently than
files.

When I started implementing socket access
in GAWK, I actually wanted to implement it
just the way you expected it (access with
"<" and ">"). But our honorable Maintainer
convinced me to implement socket access in
a different way ("|&"). The reasoning goes
like this: GAWK remembers if a "file" was
accessed with "<" or ">". These are one-
directional accesses (either read or write,
but not both). Sockets dont fit into this
scheme, therefore Arnold told me to use the
"|&" syntax, which was prepared for two-
directional access. This really makes sense
from an implementer's perspective.

From a user's perspective, I was never happy
with the "|&" syntax because users (like you)
expect things to work in a uniform way.

> More generally, it'd be nice if everything that could be done
> with ARGV/FILENAME/... to choose the upcoming filenames 'just worked'
> with sockets.

Indeed.

> It already (seems to be from the limited testing) half-way there, with
> normal input processing working just fine, only with the anomaly that
> in this case, two sockets with identical names don't read and write
> correctly.

The files with identical name are not much better.

> On linux at least, /dev/tcp doesn't work.

I think Arnold forgot to mention that /dev/tcp is
a feature of the new Korn Shell (ksh93) and not
a feature of GNU Awk. Therefore, you can expect to
see a working /dev/tcp only if your shell is ksh93
compatible.

In article <2rgk3dF1a9f3bU1@uni-berlin.de>,
examnotes  <Juergen.KahrsDELETETHIS@vr-web.de> wrote:
>Ian Stirling wrote:
> 
>
>Now I see what your problem actually was.
>/inet/tcp has a meaning inside GNU Awk;
>outside (in the realm of any shell) it
>has no meaning. But even inside GNU Awk
>sockets must be handled differently than
>files.
>
>When I started implementing socket access
>in GAWK, I actually wanted to implement it
>just the way you expected it (access with
>"<" and ">"). But our honorable Maintainer
>convinced me to implement socket access in
>a different way ("|&").

Editorial note: I'm not sure what the exact "state" of this discussion is,
and I don't want to get mired in it.  I will just state that I think that
Ian has been arguing in circles with himself, but beyond that I don't care.

I am stepping in only to point out that ">" does work with sockets (as
long, of course, as the communication is one-way).  My program contains:

sock="/inet/tcp/..."
print data > sock;close(sock)

and it works just fine.