## Important Files and Paths
* /etc/login.defs is the configuration file for login parameters, containing some defaults that are used for the commands below.
* /etc/adduser.conf contains the default configuration and settings for creating new users with adduser
* The default files for new users is stored in /etc/skel, though this can be changed in /etc/adduser.conf
* The user database is stored at /etc/passwd
* User passwords are stored in /etc/shadow
* Group info is stored at /etc/group

## Find all users that login through the terminal.
`sudo awk -F':' '$2 ~ "\\$" {print $1}' /etc/shadow`

## Get the groups a user belongs to.
groups `username`

## Get the GIDs a user belongs to.
id `username`
id `uid`

## Add a group
addgroup

## Add a user
* Omitting the groupname argument will cause a new group to be created with the same name as the new user.

adduser `username` `groupname`

## Delete a user
deluser

## Change a users password
passwd

## Change group passwords
gpasswd

## Modify a user
* Where adduser only allows the user to be added to one group, usermod allows a user to be added to multiple groups.
usermod
chfn

## Give password an expiration date
chage

## Set a disk usage quota
edquota

## Regarding Sudo
To grant sudo privileges to an existing user,
`usermod -aG sudo username`

## Miscellaneous
To switch users without having to logout and back in,
`su - username`

## For more information:
* https://www.computerhope.com/unix/adduser.htm
* https://linux.die.net/man/8/adduser
* http://linuxadministrative.blogspot.com/2014/05/adduser-command-examples.html
* https://www.linuxtechi.com/linux-commands-to-manage-local-accounts/