Hello, and welcome to our first demonstration,
a demonstration where we're going to dive out to the
command line on our AlmaLinux 8 system,
and initially we're going to go through and check for ACL support.
And look at this,
we're walking in the lovely turf of our AlmaLinux 8 command line.
Now we want to go through and check the very basics
to see if ACLs are supported, and one easy way is just run the command.
That then is going to tell me whether or not I've got the package installed.
And if we go through and using getfacl query the etc/hosts file,
well we're getting a result coming back,
so that's telling me the file is definitely there,
getfacl.
Doesn't matter about reading the ACL at the moment,
we're going to understand more about this later,
but that's essentially telling me there isn't an ACL on that file,
that is just the standard mode.
If we want to make sure that we've got the latest version,
we could always go through and install the ACL package.
Now it's telling me there that it's already installed,
so it must also meet the latest version that is available.
So, we're up and running as far as our ACL package is concerned; however,
we do need to make sure that we have got support for it within our kernel.
When we look inside of our boot directory,
/boot,
we will have one or more configuration files representing
the kernels that we have on our system.
Now at the end of the file name will be the kernel release.
We can go through and check our release of our
current running kernel using uname ‑r.
When we compare this then to our file name we can see
then it's config‑ and then uname ‑r.
Now this then gives us the ability to be able to go through and
search on any system that matches this naming scheme.
We were able to then go through and search.
We're going to use it in case‑sensitive search.
It's probably going to be uppercase, but let's not worry about that.
And let's look for ACL within our kernel configuration file.
So it's going to start config‑ and then we have our variable information,
but we can easily show that and get great command line
practice by using the dollar and parentheses,
and inside of the parentheses we're going to have uname ‑r.
We then look at the output of that command and append it
to the file path that we've entered.
So giving the big Enter key on this,
we can start seeing that we have got support,
and we can see that we've got support there for EXT4 file systems,
XFS file systems,
and generic file systems that might also have their own support.
Moving down though, we have got support as well,
as we can see, for NFS and CEPHs.
So this gives us an idea that our kernel has got the modules available.
If it's marked with a y, it's compiled into the cokernel.
When we look at NFS_ACL_SUPPORT, well that's a module,
so it's loadable by the kernel.
It's a separate file that is loaded as needed by the kernel.
Now there's always more that we can get practice with,
and if I use the rpm command,
a command that's specific to our Red Hat family systems,
we can go through and query a file,
and in a similar method to what we just looked at,
rather than specifically knowing the path through to the getfacl command,
we can go through and ask which getfacl.
That's going to return the file name and the path.
Rpm ‑qf is going to show the related package.
So the getfacl command is delivered by the package ACL,
and the version number there you can see,
and we've known already that we've checked that that was installed.
So nothing too surprising here.
The next thing is to check the file systems that we have.
If I go through look at mount ‑t and then looking for the xfs file system,
we can see that, on this system at least,
the root file system is xfs.
When we look at ext4, we don't have any ext4 file systems.
So there's no further checks that we really need to concern
ourselves with because we're aware that XFS has ACL support
that is built into the file system,
and we don't need to enable it through an option.
Ext4, on most recent systems, it will be enabled by default, but it is enabled through a feature that we have to turn on.