Simple bash script to remove duplicate rows from a table:

#!/bin/bash
echo "Remove duplicate records from tbl_duplicates"
mysql -uusername -ppassword database -e "DELETE n1 FROM tbl_duplicates n1, tbl_duplicates n2 WHERE n1.col_id > n2.col_id AND n1.col_duplicate = n2.col_duplicate;"

Terms mentioned:

tbl_duplicates – table to remove duplicates from
col_id – column ID
col_duplicates – a column which contains duplicate data
> – this keeps the row with the lowest id