File ownership and authorizations

Under Linux®, every file and directory has an owner and a group as well as an authorization set that determines who is allowed to read, write or execute the file.

You can use the -l option of the ls command to display detailed information about files and directories, including ownership and permissions.

Example: Execute ls -la /home/Administrator. The output could look something like this:

ls -la /home/Administrator
total 28
drwx------ 1 Administrator Administrator  274  Jan  7 07:23 .
drwxr-xr-x 1 root          root           26   Nov  10 16:30 ..
-rw------- 1 Administrator Administrator  7008 Jan  6 15:48 .bash_history
-rw-r--r-- 1 Administrator Administrator  220  Nov  10 16:30 .bash_logout
-rw-r--r-- 1 Administrator Administrator  3526 Nov  10 16:30 .bashrc
-rw------- 1 Administrator Administrator  20   Jan  7 07:23 .lesshst
-rw-r--r-- 1 Administrator Administrator  807  Nov  10 16:30 .profile
drwxr-xr-x 1 Administrator Administrator  30   Dec  17 12:46 .ssh

Let's take a look at the issue from ls -l /usr/bin/ping:

-rwxr-xr-x 1 root root 156136 Apr 22 2025 /usr/bin/ping

Viewing the output column by column helps to understand the information provided:

|       1  |2|  3 | 4  |    5 |         6  |          7  |
|----------|-|----|----|------|------------|-------------|
|-rwxr-xr-x|1|root|root|156136|Apr 22 2025|/usr/bin/ping|

- rwx r-x r--
│ │   │   └── Others
│ │   └────── Group
│ └────────── Owner
└──────────── File Type

1. The first column shows the file permissions -rwx r-x r--.

• The first hyphen means that it is a normal file.
• This is followed by three groups of three, which specify the read, write and execute rights for the owner, group and others.
• In this case, the owner has rwx (read, write, execute), the group has r-x (read, execute) and others have r-- (read).
• In binary notation, this corresponds to 111 101 100, which results in 754 in octal notation.
• In symbolic notation: u=rwx,g=rx,o=r.

1. The second column shows the number of hard links to the file or directory.
2. The third column shows the owner (root in this case).
3. The fourth column shows the group (here also root).
4. The fifth column shows the size of the file in bytes.
5. The sixth column shows the date and time of the last change.
6. The seventh column shows the name of the file or directory.