Managing users should be a pretty straight forward task. While the User Manager provided by Sitecore is handy, you'll likely find yourself wanting to make bulk changes. The following examples should give you a few ideas about how to manage user accounts.
Query users and update properties
Example: The following generates a batch of test users in the default domain with the out-of-the-box user profile template. The users are then queried filtering on the name.
When using the Active Directory module you may need to increase the setting LDAP.SizeLimit if you wish to return all Active Directory accounts.
Using Set-User to update AD accounts may result in an "Access denied message"; this is due to the fact that the account querying user does not have write access to profile properties or the profile provider is not configured properly.
Example: The following queries roles using the specified identity.
# Identity can be "[domain]\[name]", "Creator-Owner", and "\Everyone"
Get-Role -Identity "default\Everyone"
Item Access Control Lists (ACL)
The ACL commands provide an automated way of granting privileges to items.
Example: The following creates a new ACL and assigns to an item.