Linux: File Permissions

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From the course by Google

Operating Systems and You: Becoming a Power User

2541 ratings

Google

Operating Systems and You: Becoming a Power User

2541 ratings

Course 3 of 5 in the Specialization Google IT Support Professional Certificate

In this course -- through a combination of video lectures, demonstrations, and hands-on practice -- you’ll learn about the main components of an operating system and how to perform critical tasks like managing software and users, and configuring hardware. We’ll wrap up with an example of how you might see this content show up in an interview setting. By the end of this course you’ll be able to: ● navigate the Windows and Linux filesystems using a graphical user interface and command line interpreter. ● set up users, groups, and permissions for account access. ● install, configure, and remove software on the Windows and Linux operating systems. ● configure disk partitions and filesystems. ● understand how system processes work and how to manage them. ● work with system logs and remote connection tools. ● utilize operating system knowledge to troubleshoot common issues in an IT Support Specialist role.

From the lesson

Users and Permissions

In the second week of this course, we'll learn about configuring users and permissions in Windows and Linux OS. As an IT Support Specialist, it's important to know how to grant the appropriate permissions to users and groups for both Windows and Linux OS. By the end of this module, you will know how to add, modify, and remove users for a computer and for specific files and folders by using the Windows GUI, Windows CLI, and Linux shell.

Windows: File Permissions5:48

Linux: File Permissions2:55

Windows: Modifying Permissions7:19

Linux: Modifying Permissions4:56

Windows: Special Permissions4:59

Linux: SetUID, SetGID, Sticky Bit5:52

Meet the Instructors

Google

As we've now learned, there are files and

folders that have different permissions set on them,

so that unwanted eyes can't view or modify them.

There are 3 different permissions that you can have in Linux;

Read, this allows someone to read the contents of a file or folder.

Write, this allows someone to write information to a file or folder.

And execute, this allows someone to execute a program.

Let's take a look at this with the LS command,

we'll use the long flags so we can see the permissions on the file.

Okay. The first thing we see in this column is -rwxrw-r-- there are 10 bits here.

The first one is the file type.

In this example, dash means that the file we're looking at is just a regular file.

Sometimes you might see D which stands for a directory.

The next nine bits are our actual permissions,

they're grouped in trios or sets of three.

The first trio refers to the permission of the owner of the file.

The second trio refers to the permission of the group that this file belongs to.

The last trio refers to the permission of all other users.

The R stands for readable,

W stands for writeable and X stands for executable.

Like in binary, if a bit is set then we say that it's enabled.

So for our permissions,

if a bit is a dash it's disabled.

If it has something other than a dash, it's enabled.

Permissions in Linux are super flexible and powerful,

because they allow us to set specific permissions based on our role.

Such as an owner in a group or everyone else.

Let's take a look at this in detail.

The first set of permissions, rwx,

refers to the permission of the user who owns that file.

In this case, its Cindy.

We can see in the owner field of ls-

l. So it says here that the owner of the file can read,

write, and execute this file.

The next set of permissions are group permissions.

We can see the group this file belongs to is the cool group.

They have read and write permissions but not execute permissions.

And lastly, the permissions for

all other users and groups only allow them to read this file.

And that's Linux permissions in a nutshell,

it might take some time to get used to reading permissions.

Don't worry, you'll eventually get the hang of it.

As always, feel free to review this lesson again if you need a refresher.

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