Day-17 File Permissions in Linux

OK, so tomorrow, we checked the Linux file system where we looked over a few directories and commands. Today we are going to check file permissions and how you can modify them using chmod.

You may have noticed that sometimes you want to access one file but you can't. It throws some errors like Permission denied. That is because you don't have access to that file.

File permissions 🗄️🔐

As discussed in the previous blog, Linux is made up of a lot of configuration files. Many critical (IMP) files require administrator permissions to r (read), w (write), and x (execute).

Checkout the above image. When you type ls -l it will give you a more detailed view of the listed files currently available in your current folder.

Let's breakdown that output. Here I have a total of 115696, items in my home directory. Here it represents the size of the file, who is the user, when it was created, and its name.

I don't have much interest in the above details, but I want to know what those first 10 letters( -rw-rw-r--)? What is the use of that?

Actually it is divided in four parts.

1. -: It represents file type.

   • d stands for directory.
   • c stands for character.
   • - stands for file.
   • l stands for link.

2. rwx: It shows user permissions. What sort of permissions does the user have for that specific file or folder?

3. r-x: It stands for group permissions. A group can contain multiple users and can have different permissions.

4. r-x: This is for other users available in the system.

Changing File Permissions

Chmod

So now you know about file permissions, now what? How about changing file permissions? But how? There is one command chmod you can use to change file permissions.

See above image. We first created a test.txt file and checked its permissions. For other users, it was r-- only(reading permission only). Later, we gave w permission to o(other) using chmod. Here + used to add a new permission.

There are also numeric representation available for these permissions. Check out this to know more about that.

Resources & Ending notes 📚👋

• Linux File Permissions
• Understand Linux File Permissions

That was it for the topic of permissions and chmod. I'll be back with a new topic tomorrow.