How to correctly set the ORACLE_HOME variable on Ubuntu 9.x?

Usually the msb file not found problems are the result of an environment setting problem, but in your case I’m a little suspicious of the installation (I’ve never used the apt-get + configure method).

To check the sanity of the installation:

• ORACLE_HOME should be set to a directory path one level above the bin directory where sqlplus executable is found.
• There should some .msb files under $ORACLE_HOME/sqlplus/mesg
• There should be hundreds (not sure of the number with XE) of .msb files
  under $ORACLE_HOME (try find $ORACLE_HOME -name "*.msb" -print to show them)
• Your PATH should include $ORACLE_HOME/bin.
• All files under ORACLE_HOME should be owned by user:oracle group:dba.