I use IBM Datastage for ETL at work. Datastage has an "Execute Command Activity" which allows us to issue an command on the operating system, in our case it's a linux.
Below are the commands that have come in very handy and efficient in helping me process the data or augment my data workflow.
To convert a single column into a comma separated row of values:
paste -s -d, your_input_file
To get last row:
tail -1 your_input_file