Message file RMAN.msb not found

Error Description
I give the full path of rman executable file location and I am getting error RMAN<>.msb not found as below.
-bash-3.1$ /oradata2/bin/rman target /
Message file RMAN<>.msb not found

Verify that ORACLE_HOME is set properly

Solution of The problem
Believe me, as I still got you have not set ORACLE_HOME properly. So set it.

To know your current settings of ORACLE_HOME, issue,
-bash-3.1$ echo $ORACLE_HOME
/oradata2/bin/

Here we see it is set, it may either unset. Though it is set wrong. The ORACLE_HOME path is before the bin directory. So here ORACLE_HOME will be /oradata2 instead of /oradata2/bin/

On unix set the value for the current session by,
-bash-3.1$ export ORACLE_HOME=/oradata2/

On Windows environment you have to set by
set ORACLE_HOME=C:\oracle or like that.

In order to set it permanently edit your profile. On linux like, ~/.bash_profile or on unix edit the file .profile on home directory and make an entry of ORACLE_HOME.

After setting correct ORACLE_HOME now try to connect to rman.
-bash-3.1$ /oradata2/bin/rman target /

Recovery Manager: Release 10.2.0.1.0 - Production on Thu Aug 28 14:37:53 2008

Copyright (c) 1982, 2005, Oracle. All rights reserved.

connected to target database (not started)