Parsing Files with awk (and sort and uniq)

The field in /etc/passwd that holds the shell is number 7. To display the field holding the shell in /etc/passwd using awk and produce a unique list: 
$ awk -F: '{print $7}' /etc/passwd | sort -u
 or 
$ awk -F: '{print $7}' /etc/passwd | sort | uniq
 For example: 
$ awk -F: '{print $7}' /etc/passwd | sort -u
 
/bin/bash
/bin/sync
/sbin/halt
/sbin/nologin
/sbin/shutdown