copied from http://stackoverflow.com/questions/75675/how-do-i-dump-the-data-of-some-sqlite3-tables
You don't say what you wish to do with the dumped file.
I would use the following to get a CSV file, which I can import into almost everything
.mode csv .header on .out file.dmp select * from emp;
If you want to reinsert into a different SQLite database then:
.mode insert .out file.sql select * from em