• File Permissions: Permissions determine who can access (read, write, execute) a file. They are set for three categories:owner, group, and others.
• Root User and Sudo Privilege User: The root user has the highest level of access and can bypass most restrictions, including file permissions.
• Ownership of Docker Volumes:
  • Default Ownership: Docker volumes are created by the Docker daemon, which typically runs as root.

Ask: permission can’t cross user directory limitation, even with sudo

User

List All Users/Groups

# List all users
getent passwd
# or
cat /etc/passwd

# Search for a specific user
getent passwd | grep <username>  

# List user belonging group
groups username
id -Gn username

# List all groups
getent group # or cat /etc/group

# List the group users
getent group <group_name>

Get the user ID (UID) and group ID (GID)

id -u # This will display the current user's UID
id -g # This will display the current user's primary GID

id -u username # This will display the specified user's UID
id -g username # This will display the specified user's primary GID

Creating a Non-Root sudo User

Create A New User

sudo adduser <username>
sudo passwd <username>

Give The User sudo Privilege

# Use `visudo` command to open `Sudoers` file (/etc/sudoers), the command will open a vi editor.
sudo visudo

# After the `root ALL=(ALL:ALL) ALL` line, add the following line
<username>    ALL=(ALL:ALL) ALL

Switch To The User

su - <username>

Permission

[apiuser@allma-expo ~]$ ls -al
total 28
drwx------  3 apiuser apiuser 4096 May 16 17:33 .
drwxr-xr-x. 3 root    root    4096 May 16 16:39 ..
-rw-------  1 apiuser apiuser  489 May 16 17:58 .bash_history
-rw-r--r--  1 apiuser apiuser   18 Aug  3  2022 .bash_logout
-rw-r--r--  1 apiuser apiuser  141 Aug  3  2022 .bash_profile
-rw-r--r--  1 apiuser apiuser  376 Aug  3  2022 .bashrc
drwx------  2 apiuser apiuser 4096 May 16 17:29 .ssh