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 <klep...@svana.org> http://svana.org/kleptog/ > The combine: one man, one day, wheat for half a million loaves of bread.
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