[CentOS] CentOS default accounts in /etc/passwd

Sun Nov 26 10:45:54 UTC 2006
Paul Stepowski <paul.stepowski at intient.com>

Hi,

I've noticed that the /etc/passwd file on CentOS 4.4 contains the users: 
sync, shutdown, and halt.

The users' shells are set to /bin/sync, /sbin/shutdown, and /sbin/halt 
respectively.

What are these accounts used for?

Thanks,

Paul