Dynamic Listener Tracing

How to enable Listener Dynamic Tracing?Here is the answer
Sart the Listener Utility
$lsnrctl

LSNRCTL> show
The following operations are available after show
An asterisk (*) denotes a modifier or extended command:
rawmode                            displaymode                       
rules                              trc_file                          
trc_directory                      trc_level                         
log_file                           log_directory                     
log_status                         current_listener                  
inbound_connect_timeout            startup_waittime                  
snmp_visible                       save_config_on_stop               
dynamic_registration               enable_global_dynamic_endpoint    
oracle_home                        pid                               
connection_rate_limit             

LSNRCTL> set trc_directory /oradata (/oradata is created for test, you can set your own directory)
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
TNS-01251: Cannot set trace/log directory under ADR

Note:- set the below parameter in listener.ora (default  is on)
DIAG_ADR_ENABLED_<listener_name> = OFF

Reload the listener,
LSNRCTL> reload
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
The command completed successfully

LSNRCTL> set trc_directory /oradata
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
TNS-01178: Trace Level is 0. Trace file/directory unchanged

Follow the below sequence to supress TNS-01178 (as the error is itself descriptive)
LSNRCTL> set trc_level 8
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
LISTENER parameter "trc_level" set to admin
The command completed successfully
LSNRCTL> set trc_file lisn.trc
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
LISTENER parameter "trc_file" set to lisn.trc
The command completed successfully
LSNRCTL> set trc_directory /oradata
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
LISTENER parameter "trc_directory" set to /oradata
The command completed successfully
LSNRCTL> exit

Verify the trace file is created in the desired directory or not.

$ cd /oradata
[oracle@localhost-pub oradata]$ ls -ltr
-rw-r-----. 1 oracle oinstall 41662 May 28 09:49 lisn.trc

[oracle@localhost-pub oradata]$ lsnrctl status
LSNRCTL for Linux: Version 11.2.0.3.0 - Production on 28-MAY-2013 09:53:09
Copyright (c) 1991, 2011, Oracle.  All rights reserved.
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
STATUS of the LISTENER
------------------------
Alias                     LISTENER
Version                   TNSLSNR for Linux: Version 11.2.0.3.0 - Production
Start Date                27-MAY-2013 23:34:54
Uptime                    0 days 10 hr. 18 min. 15 sec
Trace Level               admin
Security                  ON: Local OS Authentication
SNMP                      OFF
Listener Parameter File   /u01/app/oracle/product/11.2.0/dbhome_1/network/admin/listener.ora
Listener Log File         /u01/app/oracle/product/11.2.0/dbhome_1/network/log/listener.log

Listener Trace File       /oradata/lisn.trcListening Endpoints Summary...
  (DESCRIPTION=(ADDRESS=(PROTOCOL=tcp)(HOST=localhost-pub)(PORT=1521)))
Services Summary...
Service "pr" has 2 instance(s).

Switch of the dynamic listener tracing.

LSNRCTL> set trc_level off
Connecting to (DESCRIPTION=(ADDRESS=(HOST=localhost-pub)(PROTOCOL=TCP)(PORT=1521)))
LISTENER parameter "trc_level" set to off
The command completed successfully
LSNRCTL>

TEST!TEST!TEST