How do I check to see if Intelligent Agent is installed

From Oracle Documentation:

Controlling Operations of the UNIX Agent
On UNIX, the lsnrctl command is used to start and stop the agent. The relevant lsnrctl commands are listed in the table below.

If you want to...   Enter the command...  
Start the agent on UNIX platforms  
 lsnrctl dbsnmp_start  
 
Stop the agent on the UNIX platform  
 lsnrctl dbsnmp_stop  
 
Verify status of the agent  
 lsnrctl dbsnmp_status  
 

To see if it is installed:

Go to $ORACLE_HOME/bin
type ls -al dbsnmp

If you see the executable such as:
-rwxr-xr-x   1 oracle   dba      3287696 Dec 22 14:31 dbsnmp

Then you know it is installed.

Regards,
Melanie

when I type:
 lsnrctl dbsnmp_status  

I get this:
NL-00853: undefined command "dbsnmp_status".  Try "help"

When I type:

Go to $ORACLE_HOME/bin
type ls -al dbsnmp

I get this:

-rwsr-s---   1 oracle   dba      2986436 Mar 31 14:12 dbsnmp

I am not sure what this means. Is the Intelligent Agent disabled? Because it appears to be installed.

If you can see this file - Intelligent Agent is allready installed

Run command in terminal:
ps -edf | grep dbsnmp

If process exists then Agent is running

Does this mean that the Agent is running?:

 root 23446 23441  0 20:52:25 pts/2    0:00 grep dbsnmp

I got nothing when I entered ps -edf | grep dbsnmp | grep -v grep

ok thanks