My file bash, and configurate for linux
whoami
groups
id
users # active sessions
who # active sesions
w # active sesions
su <user> # switch user / subsitute user
sudo su # super user do
/etc/passwd
/etc/group
useradd <nameuser>
useradd <nameuser> -m # m => with home dir, M => without home dir
useradd <nameuser> -m -d /home/nama # with dir
useradd <nameuser> -m -d /home/nama -s /bin/sh # with shell
useradd d -m -d /home/d -s /bin/bash
useradd -D
  GROUP=100
  HOME=/home
  INACTIVE=-1
  EXPIRE=
  SHELL=/bin/sh
  SKEL=/etc/skel
  CREATE_MAIL_SPOOL=no
sudo adduser e
Adding user `e' ...
Adding new group `e' (1009) ...
Adding new user `e' (1008) with group `e' ...
Creating home directory `/home/e' ...
Copying files from `/etc/skel' ...
New password:
Retype new password:
passwd: password updated successfully
Changing the user information for e
Enter the new value, or press ENTER for the default
        Full Name []: e
        Room Number []: e
        Work Phone []: e
        Home Phone []: e
        Other []: e
Is the information correct? [Y/n] y
passwd <nameuser> # change password for user
user:x:id:gid:fullname:
# x => real pass in /etc/shadow
group:x:gid:[members]
## blocking user
usermod -L name # lock
usermod -U name # unlock
    ### if u make lock user in /etc/shadow ur hash into !$hash from $hash
usermod -d /home/user99 user99
usermod -s /bin/bash user99