How to remove a COMMA from a .txt file using an ANT script command

I have an ANT script and an SQL script. The ANT script makes the SQL script to run against the database and it generates a .txt file with multiple rows. The .txt file contains values like:

'value1',
'value2',
'value3',
 .
 .
'valueN',

I want to remove the COMMA in the last row. Is there any ANT command that I can use to make this happen?

I am new to both ANT and SQL