🌟Day 6 -File Permissions and Access Control Lists

🔈File Permissions with Examples

Linux file permissions are used to control who can read, write, and execute a file. This is important because Linux systems are multi-user, and file permissions are a security mechanism that protects system files from users and viruses.

Mainly Linux has three types of file permissions:

• Read (r): Allows a user or group to view a file.

• Write (w): Allows a user to write or modify a file or directory.

• Execute (x): Allows a user or group to execute a file or view a directory.

◼️How do you view Linux file permissions?

• ls -l: The ls command along with its -l (for long listing) option will show you metadata about your Linux files, including the permissions set on the file.

Here is Some examples:

✔️Create a simple file and do ls -ltr to see the details of the files:

ls -ltr

• ✔️owner — The owner of the file or application and If you want to change the ownership of a file and directory use "chown".

  chown newowner file.txt

• ✔️group — The group that owns the file or application and To change the group permission of file and directory use "chgrp".

  chgrp newgroup file.txt

• ✔️To change the other users permissions of a file or directory used "chmod"

  chmod o+r file.txt - set permission read only

  chmod o+w file.txt - set permission write only

  chmod o+x file.txt - set permission execute only

  🔈Access Control List (ACL)

  It is a mechanism for controlling access to file and directories on a Linux System. ACLs allows you to specify permissions for individual users and groups.

• ✔️To view the Access Control List for a file or directory, use getfacl command.

  e.g. To view the ACLs for the file /etc/passwd

  getfacl /etc/passwd

• ✔️To set or modify the Access Control List for a file or directory, use setfacl command.

  e.g. To add the user newuser to the ACL for the file /etc/passwd with read and write permissions use setfacl -m command.

  setfacl u:newuser:rw /etc/passwd

• ✔️To set the Access Control List for a file or directory, For group use setfacl -m command.

  • e.g. To set all permission to group Devops with read and write and execute permissions for directory repo.

    setfacl -m g:Devops:rwx /repo

• ✔️To remove modify the Access Control List for a file or directory, For group Devops use setfacl -x command.

  • e.g. To set all permission to group Devops with read and write and execute permissions for directory repo.

    setfacl -m g:Devops:rwx /repo

• ✔️To remove modify the Access Control List for a file or directory, For newuser use setfacl -x command.

  • e.g. To remove all permission to newuser for directory repo.

    setfacl -x u:newuser: /repo

• ♻️Conclusion

  Understanding file permissions and Access Control Lists (ACLs) is vital for securing computing environments. File permissions in Linux regulate access, while ACLs provide granular control.

📚 Happy Learning :)