title: unable to connect to DB using sqlplus: ORA-12154: TNS:could not resolve the connect identifier specified
body: <p>I'm trying to connect to connect to DB through <code>sqlplus</code> from one of the Linux servers, but getting below error:</p>
  
  <pre><code>SQL*Plus: Release 12.1.0.2.0 Production on Thu May 16 15:49:15 2019
  
  Copyright (c) 1982, 2014, Oracle.  All rights reserved.
  
  ERROR:
  ORA-12154: TNS:could not resolve the connect identifier specified
  
  
  Enter user-name:
  </code></pre>
  
  <p>I re-installed <code>oracle</code> client in my server, hoping it'll resolve the issue,but no luck!</p>
  
  <p>Usage:</p>
  
  <pre><code>$&gt;sqlplus user_name/passwd@SID
  </code></pre>
  
  <p>Any help is most welcome!!!</p>