Day 6 Task: File Permissions and Access Control Lists

#90DAYSOFDEVOPSCHALLENGE

The concept of Linux File permission and ownership is important in Linux. Here, we will be working on Linux permissions and ownership and will do tasks on both of them. Let us start with the Permissions.

Permission : Linux is a multi-user operating system, so it has security to prevent people from accessing each other’s confidential files. Every file, directory, and other system objects in Linux are assigned an owner, a group and an otheruser. This is the most basic, yet essential, part of system security that protects users from each other. Owners, users belonging to a group, and all others may be granted different types of access to read from, write to, or execute files. This is generally referred to as file permissions in Linux.

Types of Permissions Groups:
Owners: The owner's permissions will only apply to owner of the file / directory,
        determine what actions the owner of the file can perform on the file 
        and will not affect the other groups.

Groups: The group's permissions you can assign a group of users specific 
        permission, which will only impact users within the group.

Otherusers: The permissions for others indicate what action all other users 
             can perform on the file.

Types of file permissions:

Read permission: Allows a user or group to read/view the contents of the file

Write permission: Allows a user or group to modify the contents of the file

Execute permission: Allows a user or group to execute or run a file as a program.

1. Create a simple file and do ls -l command to see the details of the files

Some command to change the file permission

· Chown command : Used to Change the ownership permission of a file or directory

Syntax : 1. Sudo chown root filename, here you can see after using chown command ownership is changed to root user

Syntax : 2. Sudo chow root:root filename, here you see after using chmod root:root comand ownership and groupuser aslo changed to root user

· Chmod command : Used to change the users permission of file/directory

Syntax :
sudo chmod +r filename = Owner & groups get only reading access.
sudo chmod +w filename = Owner & groups get only writing access.
sudo chmod +x filename = Owner & groups get only executing access.

Here you see after using chmod +x command to file_permission.txt , the onwer,group user, otheruser have execute access.

2. What is Access Control List (ACL)

ACLs allow us to apply a more specific set of permissions to a file or directory without (necessarily) changing the base ownership and permissions. They let us “tack on” access for other users or groups.

Some Commands: setfacl and getfacl are used for setting up ACL and showing ACL respectively.

· getfacl- Displays access permissions of files and directories with filename, owner, group and the ACL’s.

Syntax: getfacl filename/directory name

· setfacl- Helps in adding permissions to user and groups.

Syntax: setfacl -m u/g:username/groupname:permissions /path of file

I Hope you find this article useful.

Thank you so much for taking the time to read my article.

Basanagouda Patil

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