File Ownership in Linux/Ubunto

This Lecture teaches you the following topics:

• Changing ownership of a file
• Creating a user/group account using CLI
• Deleting user/group account using CLI

Changing Ownership and Group

1. Changing the ownership of a file/directory

For changing the ownership of a file/directory, you can use the following command:

chown user filename/directoryname

2. Changing the both group and user owner of a file/directory

In case you want to change the user as well as group for a file or directory use the command

chown user:group filename

3. Changing the group owner of a file/directory

In case you want to change group-owner only, use the command

chgrp group_name filename

‘chgrp’ stands for change group.

4. To Check groups

The file /etc/group contains all the groups defined in the system

cat /etc/group

5. Find all the groups, a user belongs

You can use the command “groups” to find all the groups you are a member of

6. To Change the default group

You can use the command newgrp to work as a member a group other than your default group.

The default group in our example is computer:

After changing the default group to adm:

Creating a User Account using the Command Line

To create a new user account using the Command line, follow the below steps:

1. Hit Ctrl+Alt+Tto launch the command line Terminal application in Ubuntu.
2. Now in order to create a new user account, use adduser command as follows:

 sudo adduser <username>

3. Replace <username>with your new user account name that you want to create.

Creating a new group

 To create a new group, we use the command groupadd.

sudo groupadd groupname

For Example:

sudo groupadd editorial

Adding users to group

usermod command is used to add a new user to a group.

sudo usermod -a -G editorial Rehan

-a option tells usermod we are appending.

-G option tells usermod we are appending to the group name that follows the option.

grep editorial /etc/group

The above command will search the group editorial in group file.

Deleting the User Account

deluser command is use to delete a user account. To delete the user account using the command line, use the following syntax:

 sudo deluser <username>

Deleting the Group

sudo delgroup groupname