Command line script or macro for OpenOffice

We need a simple command line script/macro for OpenOffice that can be called from a BASH script. All the script needs to do is take an input file in the form of an OpenOffice spreadsheet (.ods format) and save the fourth tab, and only the fourth tab, in the .ods spreadsheet as a standard CSV file. The script or macro must be run from the command line, that is, no interaction with the OpenOffice GUI is required, and the script or macro must itself be able to be run from within at BASH script under Linux. Perl is not acceptable as this will be folded into an existing BASH script. The input and output filenames can be fixed (i.e. they don't have to be variables). If there is a way to solve this problem without using OpenOffice directly, that is acceptable as well.