Changing OS X passwords via ARD and Command Line

This can be used for both Admin and normal user accounts (you have to have the short account name):

You can use ARD to change the admin password on the client workstations. Using the 'Send UNIX Command' to send the following command. Set "root" (sans quote marks) in the User field in the command window.

dscl . -passwd /Users/admin newpassword

replacing admin with the short name of your workstations' local admin account and newpassword with, of course, the new password. Avoid using some characters like spaces, single quotes, double quotes and other non-alphanumeric characters since they may do things in the UNIX shell that you're not going to expect. You should also TEST this with a single client (then maybe a few more) first before trying to change a large number of machines all at once. It would also be wise to have a second local admin account just in case things go wrong.

If this fails you might have to put "sudo -s" in front of the command.