6.1 Managing File Security from the CLI

For users or applications to work together, we are able to add specific users and group rights to folders.

Setting up a colleberative directory for multiple users

We will create a directory for a group of users to work in.

Start from your machine as root The following users must exist and have password greater

• Rick

• Morty

• Summer

Also create the group science.

Make sure Rick, Morty and summer are members of the science group as an additional group.

Next, create the directory /shared/science.

Now let’s start with changing the group ownership of the directory /shared/science. We will be using the below commands for this.

chown :science /shared/science

As you can see, we can do this in two ways and the result is the same. In the chown command the : means the group resulting in the following overview.

command	result
chown rick:rick /directory	changes the user and directory
chown rick /directory	changes only the user
chown :rick /directory	changes only the group
chown rick:science /directory	changes the user to rick and the group to science

The resulting directory should look like this:

[root@rhcsa shared]# ll
total 0
drwxr-xr-x.  2 root      science      6 Dec 20 14:21 science

In the above result you can see the drwxr-xr-x on the left. Lets break that down:

position	explain
d	means it is a directory
rwx	means that the user has r read w write x execute
r-x	means that the group has r read - no write x execute
r-x	means that the all other users have r read - no write x execute

Now we want to make sure the group science has the rights to create and delete (w write) files.

chmod g+w /shared/science

Resulting directory rights look like this:

drwxrwxr-x.  2 root      science      6 Dec 20 14:21 science

Now let’s restrict access to other users.

chmod 770 /shared/science

This means rwx for user, rwx for group, and - for other

Resulting directory rights looking like this:

drwxrwx---.  2 root      science      6 Dec 20 14:21 science

Checking our work

We need to change to rick to check the rights.

su - rick

Now let’s see if you can change to the directory.

cd /shared/science

And check if we can create files.

touch portals

Results:

[rick@rhcsa science]$ ll
total 0
-rw-rw-r--. 1 rick rick 0 Dec 20 14:53 portals

We want to give access to the file and to the rest of the science group members, else they cannot work with the file.

chown :science portals

The final rights on the portals file:

-rw-rw-r--. 1 rick science 0 Dec 20 14:53 portals

Let’s change to summer to see if she can add text to the file.

su - summer

Change to the directory:

cd /shared/science

Add some text using the echo command:

echo "alphacenturi" >> portals

Read the content of the file using cat:

cat portals

Resulting output:

[summer@rhcsa science]$ cat portals
alphacenturi

You shouldn’t have gotten any errors during this process.