Manual Page Search Parameters
JEXEC(8) System Manager's Manual JEXEC(8)

jexec — execute a command inside an existing jail

jexec [-l] [-u username | -U username] jail [command ...]

The jexec utility executes command inside the jail identified by its jid or name. If command is not specified then the user's shell is used.

The following options are available:

Execute in a clean environment. The environment is discarded except for HOME, SHELL, TERM, USER, and anything from the login class capability database for the user. PATH is set to "/bin:/usr/bin". If a user is specified (via -u or -U), commands are run from that (possibly jailed) user's directory.
username
The user name from host environment as whom the command should run. This is the default.
username
The user name from jailed environment as whom the command should run.

The following command specifies a jail by its name and utilizes the current user's shell:

# jexec name

It is also possible to specify a jail by its jid:

# jexec JID

The following command runs ‘uname -a’ in a jail called “name”. Since a command is specified explicitly, jexec does not spawn an interactive shell. Instead, jexec executes the specified command directly.

# jexec name uname -a

The following command opens a sh(1) shell in a jail with a clean environment:

# jexec -l name sh

The following command utilizes login(1) to access the jail, submitting an audit record, and displaying the user's last login, system copyright, and motd(5) message:

# jexec -l name login -f root

jail_attach(2), jail(8), jls(8)

The jexec utility was added in FreeBSD 5.1.

If the jail is not identified by jid there is a possible race in between the lookup of the jail and executing the command inside the jail. Giving a jid has a similar race as another process can stop the jail and start another one after the user looked up the jid.

August 12, 2024 dev