Linux File Permissions

Hey there, fellow tech enthusiasts! Today, we're going to dive into the intriguing world of Linux File Permissions and Ownership. 🐧

So, what's all this fuss about permissions and ownership? In Linux, every file and directory comes with a set of access rights that determine who can do what with it. These access rights are categorized into three groups:

1. Owner 👑: The owner of the file or application. This is the individual who created the file or the user who currently holds it.

2. Group 🤝: The group that owns the file or application. Groups allow multiple users to share common permissions on files, making it easier to manage access.

3. Others 🌍: Everyone else on the system who is not the owner or part of the group. These users have the least privileged access.

   Now, let's get hands-on and play with some commands! 😎

   Changing Ownership and Group 🧑‍🤝‍🧑🧑‍👧‍👧

   Suppose we have a directory named "project_files" with its current owner as "Shubham" and group as "Trainwithshubham." Now, we want to change the ownership to "aryan" and the group to "Explorewitharyan."

     $ ls -l project_files
     drwxr-xr-x 3 Shubham Trainwithshubham 4096 Jul 20 12:00 project_files
   
     $ sudo chown aryan:Explorewitharyan project_files
     $ ls -l project_files
     drwxr-xr-x 3 aryan Explorewitharyann 4096 Jul 20 12:00 project_files
   

   Now, "aryan" is the owner, and "Explorewitharyan" is the new group for the "project_files" directory.

   😎 Group Permission: The group refers to a collection of users who share common access rights to the file. When a file is created, it inherits the group of the user who created it. The chgrp command is used to change the group ownership of a file:

     chgrp new_group file.txt
   

   To change permissions for the owner, group, and others simultaneously, we can use a shorthand notation with chmod. For instance:

     chmod u=rw,g=r,o=r file.txt
   

   This command grants read and write permissions to the owner, read permissions to the group, and read permissions to others.

   Changing Permissions Numerically

   Suppose we have a script called "my_script.sh" with the following permissions:

     $ ls -l my_script.sh
     -rwxr-xr-- 1 sana group3 1024 Jul 20 14:30 my_script.sh
   

   We want to give the owner full access, the group read and execute permissions, and others no permissions.

     $ chmod 750 my_script.sh
     $ ls -l my_script.sh
     -rwxr-x--- 1 sana group3 1024 Jul 20 14:30 my_script.sh
   

   Now, the owner has read, write, and execute permissions (7), the group has read and execute permissions (5), and others have no permissions (0).

   Here's the breakdown of the numeric codes:

   • 7 (Owner): Read (4) + Write (2) + Execute (1)

   • 5 (Group): Read (4) + Execute (1)

   • 0 (Others): (0)

Adding and Removing Permissions

You have a script named "my_script.sh," and you want to allow the owner to execute it and grant read and execute permissions to the group while removing all permissions from others.

    bashCopy code$ chmod u+x my_script.sh    # Add execute permission for the owner
    $ chmod g+rx my_script.sh   # Add read and execute permissions for the group
    $ chmod o-rwx my_script.sh  # Remove all permissions from others

😎 Remember, understanding these concepts is vital for maintaining data security and access control on your system. So, keep exploring, and don't forget to have fun with those Linux commands! 🚀🐧💻

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