Linux users and groups

users

1) useradd user

Create a user. 

2) passwd user
Create/Change password for user.

To create a new user, gennerally run 1, then 2 above, alternatively, you can use adduser user

which is a higher level command. 

adduser user group

As above but also adds user to group.

passwd -l user

Lock user, preventing logon using password.

passwd -u user 

Unlock user. 

passwd -S user  

Get Status for user. 

groups

groups username 

Shows a list of groups the current user is a member of.

id shows the numerical id's.

groupadd newgroup

Create a new group 

addgroup newgroup
Create a new group  

usermod -a -G group username

usermod -a -G group1,group2,group3 username 

append group(s) to username. Add username to group(s)

usermod -g groupname username 

Modify user's primary group (g = primary group G = secondary group)

useradd -G group username

Create a new user and assign it to group

getent group

List all groups on system.

groupdel group

Remove group 

groupmod --new-name NEW_GROUP_NAME OLD_GROUP_NAME

rename a group.