[ALUG] /etc/shadow - password field

I was looking in my /etc/shadow file to see which users had passwords (so I could change them to something more secure, I know some are rubbish at the moment) and now I'm not sure what the password field is signifying. Most of the non-login 'system' accounts like 'bin' have a password field of '*', but there are a couple ('postgres' and another) which have a password field of '!'. Do both '!' and '*' indicate no password? -- Chris Green (chris@areti.co.uk) "Never ascribe to malice that which can be explained by incompetence."