From: Tom Lane <tgl@sss.pgh.pa.us>
To: dbx postgres <dbx2postgres@gmail.com>
cc: pgsql-admin <pgsql-admin@postgresql.org>
Subject: Re: psql error
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References: 
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Comments: In-reply-to dbx postgres <dbx2postgres@gmail.com>
	message dated "Wed, 21 Mar 2018 12:20:38 -0500"
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Date: Wed, 21 Mar 2018 15:06:36 -0400
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dbx postgres <dbx2postgres@gmail.com> writes:
> I have postgres running on my server but when i try to run psql I get the
> below error

> *psql: symbol lookup error: psql: undefined symbol: PQconnectdbParams *

Apparently, you have a 9.0-or-later psql trying to use a pre-9.0 copy
of libpq.so, because that function was added in 9.0.  This would seem
to mean that you have (portions of?) at least two different PG
installations, and they're not staying out of each others' way.
Hard to say more than that with only this much data.

If this is a Linux platform, applying "ldd" to the psql executable
would reveal which libpq it's trying to use.

			regards, tom lane