In the following block of commands, the string "zroot" at the beginning of the dataset name should be the name of the base zfs filesystem. bsdinstall uses zroot, so this is literally correct in that case, but I have multiple filesystems including "zpool" and "zpools". Maybe "In the following commands, replace zroot with the file system name if it is different."

It doesn't need an IP; does it serve any purpose? It works fine without one. Note, though, that "up" is needed when there is no IP. Also note that the ifconfig command has "init" duplicated.

s/Both/Either/, and this sentence should probably all be on one line.

This should use ${bridge}.

It is probably worth mentioning that the install step is run twice because it does only the kernel on the first invocation, and the rest the second time. Also, I'd recommend another restart at the end to start all the daemons with any new binaries and libraries.

I would definitely do another restart after the second install in this case, you can be sure that libraries and daemons would be updated.

Autocorrect again; that's "inet" that's duplicated.

"ways of configuration" sounds a little strange to me.

This is my attempt to make this section concise without losing much critical information.

Is -p necessary? You already created the parent dataset above.

into a different types --> into different types

I don't think this paragraph belongs here in the "Thin Jails" section.
I would remove it or add a table with pros and cons for the 4 types of jails described before.

I would remove this point. The disk space usage reduction is already mention in the first item.

uses OpenZFS or UFS as the file system. --> uses OpenZFS or UFS as file system.

I would drop the but I might be wrong here.

Can we simplify the sentence too?

The FreeBSD version running in the jail can not be newer that the version running in the host

Shorter: The man:jail[8] utility manages jails.

This is actually not true :-)

This works as any other service (or many of them): if the service is in /etc/rc.conf, you can use start, stop, etc.
If it is not, you must use onestart, onestop...

I don't have the jail service in /etc/rc.conf because I don't use jails every time I boot.
I just use the one* commands when needed.
Activating the jail service means that jails will be automatically booted.
Some people might not want that.

For consistency:

Netgraph (man:netgraph[4]) is a kernel --> man:netgraph[4] is a kernel

In general, we don't mention features and then write the link in parenthesis, we just name the thing.

another directories --> other directories

If ip4.addr = inherit then the jail inherits the address of the host.
This is usually sufficient and makes the jail work even if the host ip address changes.
I can't find were this is documented though.

Officially --> In principle

Just a suggestion.

The last step will be --> The last step is

I would use inherit here too.

The first step will be --> The first step is

With the userland extracted in the templates directory, will be necessary --> Once the userland is extracted n the templates directory, it will be necessary

With the files moved to the template, the next thing --> The next thing

bridge --> man:bridge[4]

without rebooting executing the --> without rebooting by executing the

With the machine created --> Once the machine has been created

A brief introduction of man:jexec[8] might be nice.

Also, I don't see the -f option in the manual page.
If the goal is going inside the jail as root, I think

jexec -u root ubuntu

should be enough

When the process has finished and is displayed on the console Base system installed successfully, --> When the process has finished and the message Base system installed successfully is displayed on the console ,

This removes the jail. Do we want that or do we want to do

service jail  ubuntu stop

or

service jail  ubuntu onestop

I would simplify this with something like:

Once the jail is created, there are a number of operations that can be performed like starting, rebooting or deleting the jail, installing software in it, etc.

will be used --> is used

jalil --> jail

classic --> classic

Same as above. Is this the preferred way?

What is -f?

I would split this:

Jails *must be updated from the host* operating system.
The default behavior in FreeBSD is to disallow the use of man:chflags[1] in a jail.
This will prevent the update of some fails so updating from withing the jail will fail.

Drop then

the vast majority --> the majority

it is very easy to update them --> they are very easy to update

I would separate the above and below with a full stop.

it will be enough to keep the template updated. --> it is enough to update the template

This line renders weirdly: rctl -a is in a line and the rest in the next line.

s/host system's/template's/

This doesn't seem to be true; using a template, the jail doesn't share with the host system. It is possible to have multiple templates of different versions.

s/host system/template/

I agree with splitting this, but I don't think VNET jails are "primarily" a network configuration mechanism; they have all the attributes of other jails as well. Maybe change "are primarily" to "add".

In addition, jail(8) doesn't really create or remove jails; it starts them or stops them. The proposed change avoids that confusion.

Although this is true, it is simpler to describe just one way of starting jails. My guess is that most people will want jails started at boot. Maybe we shouldn't use the word "necessary" though, or just change "activate" to "start".

Sounds better, but maybe change "two" to "several" (including netgraph, which is in this list).

What is releases for? I don't understand why media, releases, and templates would all be needed. I don't see any use of releases in the instructions. Note, if you delete it, it appears as a zfs create and a mkdir below.

How about ip6 addresses?

I don't understand this sentence.

s/This/These/

or jail.conf.d?

or jail.conf.d

But this shouldn't be here, it is the nullfs section.

Again, OpenZFS in the nullfs section; just remove it.

I don't understand why the skeleton directory is used. Maybe a sentence of explanation?

OpenZFS again...

Removed, we have enough text in this chapter :)

Removed :)

Much better :)

Sure!

I added it at the first beginnings of rewriting the chapter, but in the end I discarded it, removed :)

Done, I put the list of values in the ip4.addr entry instead of touching the example.

I have deleted it, you are right, it is unnecessary

Changed here to show an example

No, at the end you can use NullFS no mater if you're using OpenZFS or UFS.

This is true, but I prefer to make a section explaining the configuration file and then use a custom configuration for each kind of jail

good catch!

I changed, the -f option is for the login command

Good catch!