How to View ACLs using getfacl in Linux

How to View ACLs using `getfacl`

In Linux, Access Control Lists—or ACLs—allow you to set more advanced permissions than the traditional user-group-other model. You can give specific users or groups read, write, or execute permissions on a file or directory—even if they're not the owner.

In this tutorial, you’ll learn how to view ACLs on any file or directory using the getfacl command.

Step 1: Open your Terminal

You can open the terminal on your Linux system using Ctrl + Alt + T or from your application menu.

Step 2: Check if ACL is supported

Most modern Linux filesystems like ext4 support ACLs, but they may need to be enabled. To check if it's supported on a mounted partition, you can use:

mount | grep acl

If your partition is mounted with acl, you're good to go.

Step 3: Use `getfacl` to view ACLs

The basic syntax is:

getfacl <filename or directory>

Let’s try an example:

getfacl myfile.txt

If ACLs are set, you might see output like this:

# file: myfile.txt
# owner: alice
# group: alice
user::rw-
user:bob:r--
group::r--
mask::r--
other::r--

Let’s break that down:

user::rw- – The file owner's permissions
user:bob:r-- – Bob has read-only access
group::r-- – The group’s permissions
mask::r-- – The maximum effective permissions for users and groups (except the owner)
other::r-- – Everyone else’s permissions

Step 4: View ACLs on a directory

You can also use getfacl on directories:

getfacl /home/alice/docs

This will list default and specific ACLs set on the directory. For example:

# file: home/alice/docs
# owner: alice
# group: alice
user::rwx
user:bob:r-x
group::r-x
mask::r-x
other::r-x

Extra Tip: List recursively

To view ACLs recursively (including all subfolders and files), use:

getfacl -R /path/to/directory

Summary

The getfacl command is your friend when you're dealing with advanced permissions in Linux. Whether you're auditing access or troubleshooting user access issues, it's a powerful tool to inspect what permissions are in place.

Coming up next, we’ll learn how to set ACLs using setfacl.