Problem running script

My requirement is

1) to write a query in a file, read the input from that file, run in postgresql and write the output(query results) into a file. I'm not able to use combination of \i and \o
Let' say I have file test.sql and in test.sql I write
select * from abc;
 Now I need to read the query from the file and write the output to a file. I tried
=>\i test.sql \o test

but that is not working. I want to write a script which reads query from file and write output in a file and I want to do everything in one script and run it background at a particular time of teh day.
2) How do I run scripts in postgresql? How do I set the shell and execute the script?

 

Regards,

Sushma