How to login as a different bash user in terminal? I have to check if my web page running locally on nginx does not work due to permission issue. My web scripts are running as _www user, so I tried to switch to _www but this does not work:

maciek@macus:~$ sudo su - _www
Password:
maciek@macus:~$ whoami
maciek


How can I do this in 10.8.5?
Use login:

$ login
login: username
Password:
Last login: Day Month Date HH:MM:SS on ttys000
$ whoami
username