Manual Pages  — JEXEC

jexec – execute a command inside an existing jail

SYNOPSIS DESCRIPTION EXAMPLES Example 1: Open a shell in a jail Example 2: Run a single command without opening a shell Example 3: Open a shell in a jail with a clean environment Example 4: Open a shell in a jail with the login command SEE ALSO HISTORY BUGS

jexec [-l] [-d working-directory] [-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:

-d working-directory
	The working directory for running commands inside the jail. The default is the jail root directory.
-l
	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), and absent the -d option, commands are run from that (possibly jailed) user's directory.
-u username
	The user name from host environment as whom the command should run. This is the default.
-U 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 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.