gpasswdcommand, but it is not used at all!
usermodcommand to modify a user account. we can use most of the options that you use with
useradd, except that you cannot create or populate a new home directory for the user.
groupdelcommand to delete a group requires only the group name; it has no options. You cannot delete any group that is the primary group of a user.
$id$salt$hashed, The $id is the algorithm used On GNU/Linux as follows: $1$ is MD5 $2a$ is Blowfish $2y$ is Blowfish $5$ is SHA-256 $6$ is SHA-512
chage -d 0 user-namewill force user to change his password in next login.
Group name:Encrypted password:Group administrators: Group members