How to create nightly backups in Linux

I'm using the the following scheduler script to create nightly backups in
Windows:

set pgpassword=mypass
set FILENAME=%DATE:~8,4%%DATE:~5,2%%DATE:~2,2%mybackup.backup
"C:\Program Files\PostgreSQL\8.1\bin\pg_dump.exe" -i -Z9 -b -v -f
"%FILENAME%" -F c -h localhost -U postgres mydb

I'm bit new to Linux. I'm using white-box linux and Postgres 8.1.4
How to create backups of database with unique name in every night ?
Is there some script sample which can be called from /etc/crontab ?

Andrus.