Access Control Lists in Linx - getfacl and setfacl

The acl command is used to manage Access Control Lists (ACLs) on Linux systems. ACLs are a way to give more fine-grained control over permissions for files and directories beyond the standard file permissions.

At first I didn't understand so well what this was about, but after using it and reading more about it, I have discovered how to truly appreciate the opportunities coming with Access Control Lists.

Here are some examples of how to use the acl command:

View the ACLs for a file:

$ getfacl filename.txt

View the ACLs for a directory and all of its contents:

$ getfacl -R /path/to/directory/

Set an ACL on a file or directory:

$ setfacl -m u:username:rw filename.txt

This sets read and write permissions for the user username on the file filename.txt.

Remove an ACL from a file or directory:

$ setfacl -x u:username filename.txt

This removes any ACLs for the user username on the file filename.txt.

Copy the ACL from one file to another:

$ getfacl filename1.txt | setfacl --set-file=- filename2.txt

This copies the ACL from filename1.txt to filename2.txt.

Modify an existing ACL:

$ setfacl -m u:username:rwx filename.txt

This adds read, write, and execute permissions for the user username on the file filename.txt.

These are just a few examples of how to use the acl command in Linux. For more information, you can refer to the manual pages (man acl) or the official documentation.

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