mklink [source] [target]: creates a symbolic link.
/d: creates a directory symbolic link. By default, mklink creates a file symbolic link.
/h: creates a hard link instead of a symbolic link.
/j: creates a Directory Junction.
/?: displays help at the command prompt.
net user [username] [password]: user control.
/ADD: adds the user.
/DOMAIN: apply modifications to the domain as well.
/PASSWORDCHG:Yes: allow user to change his/her password.
sfc: system file check.
/scannow: initiates the scan immediately
Multiple users: after Cygwin is installed it will NOT automatically update /etc/passwd and /etc/group to reflect new users added into a system. From within the Cygwin environment run the following commands to update:
mkpasswd -l > /etc/passwdmkgroup -l > /etc/group
Update CA SSL Certificates: sometimes the SSL certificate database is out of date in Cygwin. To fix this run update-ca-trust.