Reconfiguring existing jails

After creating a jail, its parameters can be modified using the jconfig, jget, and jset commands. jconfig provides an interactive TUI configurator (jsetup-tui), while jget/jset allow managing parameters from the command line.

Built-in help and examples are available for each command:

cbsd jconfig --help
cbsd jget --help
cbsd jset --help

jconfig — Interactive Configurator

Syntax

cbsd jconfig [jname=<jailname>]

Operation Modes

Without arguments — interactive jail selector:

cbsd jconfig

Opens a list of all existing jails for selection. After selecting, the jsetup-tui TUI configurator will launch with the current parameters of the selected jail.

With specifying a jail — direct launch of the configurator:

cbsd jconfig jname=myjail

Immediately opens the TUI configurator for the specified jail.

What can be changed via jconfig

jsetup-tui provides interactive forms to modify the same parameters as during jail creation:

  • Network settings (ip4_addr, interface, vnet, ci_*)
  • Permissions (allow_*)
  • Mount parameters (mount_*)
  • Lifecycle scripts (exec_*)
  • System parameters (persist, enforce_statfs, devfs_ruleset, etc.)
  • Package lists, cloud-init, environment variables
  • Base system and clone parameters

After saving changes, the configuration is applied automatically.

jget — reading jail parameters

Syntax

cbsd jget jname=<jailname> [param=<name>]

Operating modes

All parameters:

cbsd jget jname=myjail

Returns the full current configuration of jail myjail.

Specific parameter:

cbsd jget jname=myjail param=vnet

Returns only the value of the specified parameter.

Bulk retrieval:

cbsd jget jname='prod-*' param=status

Returns the status of all jails whose name starts with prod-.

jset — setting jail parameters

Syntax

cbsd jset jname=<jailname> key=value [key=value ...]

Examples

Change a single parameter:

cbsd jset jname=myjail astart=0

Disables autostart for myjail.

Change multiple parameters:

cbsd jset jname=myjail ip4_addr="10.0.0.50" interface="em1"

Enable VNET:

cbsd jset jname=myjail vnet=1 ci_ip4_addr="10.0.1.5" ci_gw4="10.0.1.254"

Bulk update:

cbsd jset jname='test*' astart=0

Disables autostart for all jails starting with test.

Bulk update via name list:

cbsd jset web1 web2 web3 devfs_ruleset=5

Practical scenarios

Quick diagnostics

Check which jails have autostart enabled:

cbsd jget jname='*' param=astart

Check IP addresses of all VNET jails:

cbsd jget jname='*' param=ip4_addr

Pre-migration preparation

Save full jail configuration before migration:

bash cbsd get =legacy > legacy-config.txt

### Mass disable autostart for maintenance

bash cbsd set ='*' astar t= 0

After maintenance, restore:

bash cbsd set ='*' astar t= 1

Fixing the network interface

If the host interface was renamed (e.g., em0 → igb0):

cbsd jset jname='*' interface="igb0"

Interactive configuration via jconfig

When you need to change multiple parameters of a single jail, it's convenient to use the TUI:

cbsd jconfig jname=myjail

This will open jsetup-tui with grouped parameter sections, validation, and the ability to undo changes.