This article is for SRE beginners and even experts that need to quickly look up a command that relates to creating users, groups, permissions and ownerships with Linux.

To create a user,

sudo adduser <username>

To delete a user,

sudo userdel <username>

To change the password of a user,

sudo passwd <username>

To create a group,

sudo groupadd <groupname>

To delete a group,

sudo groupdel <groupname>

Add user to group,

sudo adduser <username> <groupname>

Delete users from group,

sudo deluser <username> <groupname>

View all users,

sudo nano /etc/passwd

View all groups,

sudo nano /etc/group

Add permission to a directory, sudo chmod 777 <directoryname> -R

The -R flag suggests that you want to use this permission in the subdirectories of this directory

Add file ownership to user, sudo chown -R <username> <filename>

Add directory ownership to user, sudo chown -R <username> <directoryname>

Assign file ownership to group sudo chgrp -R <groupname> <filename>

Assign directory ownership to group sudo chgrp -R <groupname> <directoryname>