List all users with the dscl command

dscl -- Directory Service command line utility

http://developer.apple.com/library/mac/#documentation/Darwin/Reference/ManPages/man1/dscl.1.html

List all users or groups

$ dscl . list /users
$ dscl . list /groups

If you want to output information about each user, though, use readall:

$ dscl . readall /users
$ dscl . readall /groups

And if you need to programatically parse said information, use -plist to make your life easier:

$ dscl -plist . readall /users
$ dscl -plist . readall /groups

—
http://stackoverflow.com/a/1308064

List details about one user

$ dscl . read /users/foo