Re: psql and named pipes

From: Aidan Van Dyk <aidan(at)highrise(dot)ca>
To: Alvaro Herrera <alvherre(at)commandprompt(dot)com>
Cc: Pg Hackers <pgsql-hackers(at)postgresql(dot)org>
Subject: Re: psql and named pipes
Date: 2008-03-27 17:05:17
Message-ID: 20080327170517.GR6497@yugib.highrise.ca
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* Alvaro Herrera <alvherre(at)commandprompt(dot)com> [080327 12:58]:
> I was under the impression that I could start a "psql -f pipe" and then
> feed it commands through the pipe using echo, and expect it to hang from
> one command to the next. Of course, this doesn't work -- my guess is
> that echo sends an EOF after the line I send, so psql sees the EOF in
> the pipe and terminates.
>
> Does anyone have an idea how to go about this? I was expecting to be
> able to drive two psql sessions in parallel in a shell script -- sort of
> poor man's concurrent psql :-(

I've had to use:
while (true); do cat pipe; done | psql

The trick is that pipes "EOF"s everytime the cleint closes it. (Not
strictly true, but it appears that way to basic read()ers).

You can see a more compilcated setup I use to echo commands to a pipe
going to a psql here:
http://www.highrise.ca/aidan/postgresql/watchsql

--
Aidan Van Dyk Create like a god,
aidan(at)highrise(dot)ca command like a king,
http://www.highrise.ca/ work like a slave.

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