ssconvert is a utility shipped with Gnumeric, a command-line spreadsheet converter. It is useful when you have data in a spreadsheet and want to parse it from a script.
ssconvert -O 'separator=;' spreadsheet.ods spreadsheet.csv
This converts an ODS file to CSV using a semicolon as separator. ssconvert supports ODS, XLS, XLSX, CSV, HTML, and more.
You can also export specific sheets:
ssconvert -O 'separator=|;format=raw' --export-type=Gnumeric_stf:stf_csv spreadsheet.ods sheet2.csv
The format=raw option prevents ssconvert from reformatting numbers.
Enjoy!