Users and groups

Users

For a real person that will be logging into the server: Add a new user (newusername) with a specified ID (1000), a default home directory, and bash shell login (/bin/bash).

useradd --uid 1000 --create-home --shell /bin/bash newusername

For a service or limited use: Add a new user (serviceusername) with a specified ID (1001), specified home directory (/var/service), and no login.

useradd -u 1001 -d /var/service -U -s /usr/sbin/nologin serviceusername

Set the password for user (newusername):

passwd newusername

Groups

Add a group (newgroupname) with a specified ID (2000):

groupadd -g 2000 newgroupname

Add user (newusername) to a group (newgroupname):

usermod -a -G newgroupname newusername

Allow user (newusername) to run commands as root:

usermod -aG sudo newusername