How to enable tracing for srvctl commands

Oracle RAC

Sometime when we execute srvctl command it may fail or throw some error.but it is very difficult to find out where it is failing,SRVM_TRACE will help us to enable trace at command line and find out the stage where it is failing.
export SRVM_TRACE=true
then run the srvctl command, you will be able to find out the tracing details on the screen

[email protected] $ export SRVM_TRACE=true
[email protected] $ srvctl config srvpool
[main] [ 2011-08-02 06:26:41.157 BST ] [OPSCTLDriver.setInternalDebugLevel:198] tracing is true at level 2 to file null
[main] [ 2011-08-02 06:26:41.158 BST ] [OPSCTLDriver.main:141] SRVCTL arguments : args[0]=config args[1]=srvpool
[main] [ 2011-08-02 06:26:41.190 BST ] [Version.isPre:465] version to be checked major version to check against10