From: | Martijn van Oosterhout <kleptog(at)svana(dot)org> |
---|---|
To: | pgsql-general(at)postgresql(dot)org |
Subject: | Re: Better way to process boolean query result in shell-like situations? |
Date: | 2015-10-29 21:57:27 |
Message-ID: | 20151029215727.GA18864@svana.org |
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Thread: | |
Lists: | pgsql-general |
On Thu, Oct 29, 2015 at 02:42:00AM +0000, Tim Landscheidt wrote:
> Hi,
>
> I regularly run into the problem that I want to query a
> PostgreSQL database in a script/program and depending on a
> boolean result do one thing or the other. A typical example
> would be a Puppet Exec that creates a user only if it does
> not exist yet.
>
> But unfortunately psql always returns with the exit code 0
> if the query was run without errors. In a shell script I
> can use a query that returns an empty string for failure and
> something else for success and then test that à la:
<snip>
What I do is use grep, for example (off the top of my head):
if ! psql -qAt -c "select usename from pg_user" | grep -q USERNAME ;
then
...
If you're looking for true/false you could grep for t/f.
Hope this helps,
--
Martijn van Oosterhout <kleptog(at)svana(dot)org> http://svana.org/kleptog/
> The combine: one man, one day, wheat for half a million loaves of bread.
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