AppJail | Simple and easy-to-use tool for creating portable jails

If you want to use a custom configuration file, create one in /usr/local/etc/appjail/appjail.conf. See more details in /usr/local/share/appjail/files/default.conf. Note: It is highly recommended to put the kernel modules suggested in this document in your loader.conf(5) file to correctly start the jails on boot.
To create a very basic jail, only two things are needed: obtaining the FreeBSD components (base.txz, lib32.txz, etc.) and creating the jail using those components. Using the appjail fetch command will download the MANIFEST file to check the components. Afterwards, AppJail will download the components. By default, AppJail will only download base.txz. AppJail will extract those components into its release directory. At this point, AppJail can create a jail using the appjail quick command. In the above example, appjail quick will create a jail named myjail. Using the start option, AppJail will start the jail after its creation. The login option simply logs into the jail after startup. The appjail fetch is not necessary to run again unless you need another release with different components. More complex examples will be shown later.
A Makejail file is a sequence of instructions, line by line, where each command and its arguments are separated by a single space (ascii: 0x20). As you can see in INCLUDE, a lot of useless information such as leading spaces, comments, empty lines and other similar things are discarded. When INCLUDE compiles all Makejails into a single Makejail, appjail makejail uses it to execute the instructions. The first stage to execute is build. This stage writes a script named buildscript that takes care of building the jail. When buildscript successfully completes its execution, the initscript is written to the jail directory, overwriting another initscript (if any). appjail makejail executes the commands in certain order. First, the ARG command is executed, second, OPTION (build only), and the rest ot the commands are executed in the order they appear. Now, we can write a Makejail. To run this Makejail, use appjail makejail. Remember that the -f parameter can use the methods described in INCLUDE and if you do not use a name for the jail with -j, a random name is chosen.