I'm trying to execute psql commands using exec kubernetes java client API, for example:

final Process proc = exec.exec(pod,  new String []{"sh", "-c",  "su  postgres -c 'psql -c 'SELECT schema_name FROM information_schema.schemata';'"} , true, true);

for some reason I get no results as output, it just prints this:

--
(1 row)

Even though when I simply use kubectl exec directly the SELECT commands return the results correctly.

Is there something I'm missing? Any help would be appreciated.