LD_LIBRARY_PATH *must* be set before perl is loaded.

Generally, yes, but for loading the propritary DLLs required by DBD::Oracle, no. It is sufficient to set up the environment variables before DBD::Oracle is loaded.

This should also work:

#!/usr/bin/perl

use lib '/home/install/perl'; 

BEGIN {
    # Setup Environment for Oracle - has to happen *before* DBD::Oracl
+e is loaded,
    # and because DBI loads DBD::Oracle during its startup, this has t
+o happen
    # before the first "use DBI".
    $ENV{'ORACLE_HOME'}="/home/root/home/xyzco/oracle/oracle/product/1
+2.1.0/dbHome_1";
    $ENV{'LD_LIBRARY_PATH'}="/home/root/home/xyzco/oracle/oracle/produ
+ct/12.1.0/dbHome_1/lib:/lib:/usr/lib";
}

use DBI;

print $ENV{'LD_LIBRARY_PATH'};

$dbh = DBI->connect("dbi:Oracle:host=127.0.0.1;sid=V1011679;port=1521"
+, "user", "password", { AutoCommit => 1});
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Alexander