Find out when a userid was created

[TeleBOYWONDER]

How do I find out when a userid was created? Can a do a "ls-c" or is there another command that would be appropriate.
Bascially, I want to compare when a user account was created to the last time it was accessed. What I would like to do, in the future with upgrade is not install or copy userids that have not been used for say 6 months.

I hope this makes sense if not ask me questions and hopefully I can make it more clear!

Thanks.

 

[iribach]

who cares 'when a userid was created' ?
you want exclude users not active since x-time!
on a s5r4 sys look for inactive flag in: man shadow
BUT
delete users it's not really a good idea.
tomorrow, my be you have to read a backup &&
would like to identify the (deleted) user
AND
why delete users ? are you out of uid ? space in /etc ?