1.\" 2.\" Copyright (c) 2003 Mike Barcroft <mike@FreeBSD.org> 3.\" All rights reserved. 4.\" 5.\" Redistribution and use in source and binary forms, with or without 6.\" modification, are permitted provided that the following conditions 7.\" are met: 8.\" 1. Redistributions of source code must retain the above copyright 9.\" notice, this list of conditions and the following disclaimer. 10.\" 2. Redistributions in binary form must reproduce the above copyright 11.\" notice, this list of conditions and the following disclaimer in the 12.\" documentation and/or other materials provided with the distribution. 13.\" 14.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24.\" SUCH DAMAGE. 25.\" 26.Dd January 11, 2026 27.Dt JEXEC 8 28.Os 29.Sh NAME 30.Nm jexec 31.Nd "execute a command inside an existing jail" 32.Sh SYNOPSIS 33.Nm 34.Op Fl l 35.Op Fl d Ar working-directory 36.Op Oo Fl e Ar name Ns = Ns Ar value Oc ... 37.Op Fl u Ar username | Fl U Ar username 38.Ar jail Op Ar command ... 39.Sh DESCRIPTION 40The 41.Nm 42utility executes 43.Ar command 44inside the 45.Ar jail 46identified by its jid or name. 47If 48.Ar command 49is not specified then the user's shell is used. 50.Pp 51The following options are available: 52.Bl -tag -width indent 53.It Fl d Ar working-directory 54The working directory for running commands inside the jail. 55The default is the jail root directory. 56.It Fl l 57Execute in a clean environment. 58The environment is discarded except for 59.Ev HOME , SHELL , TERM , USER , 60and anything from the login class capability database for the user. 61.Ev PATH 62is set to "/bin:/usr/bin". 63If a user is specified (via 64.Fl u 65or 66.Fl U ) , 67and absent the 68.Fl d 69option, commands are run from that (possibly jailed) user's directory. 70.It Fl e Ar name Ns = Ns Ar value 71Set environment variables. 72.Pp 73This parameter allows arbitrary environment variables that are available to the process 74to be executed inside of the jail, overwriting any previously defined environment variables, 75such as those specified by the 76.Fl l 77parameter. 78.Pp 79This option can be set multiple times. 80.It Fl u Ar username 81The user name from host environment as whom the 82.Ar command 83should run. 84This is the default. 85.It Fl U Ar username 86The user name from jailed environment as whom the 87.Ar command 88should run. 89.El 90.Sh EXAMPLES 91.Ss Example 1 : Open a shell in a jail 92The following command specifies a jail by its name and utilizes the current 93user's shell: 94.Pp 95.Dl # jexec name 96.Pp 97It is also possible to specify a jail by its jid: 98.Pp 99.Dl # jexec JID 100.Ss Example 2 : Run a single command without opening a shell 101The following command runs 102.Ql uname -a 103in a jail called 104.Dq name . 105Since a command is specified explicitly, 106.Nm 107does not spawn an interactive shell. 108Instead, 109.Nm 110executes the specified command directly. 111.Pp 112.Dl # jexec name uname -a 113.Ss Example 3 : Open a shell in a jail with a clean environment 114The following command opens a 115.Xr sh 1 116shell in a jail with a clean environment: 117.Pp 118.Dl # jexec -l name sh 119.Ss Example 4 : Open a shell in a jail with the login command 120The following command utilizes 121.Xr login 1 122to access the jail, submitting an audit record, and displaying the 123user's last login, system copyright, and 124.Xr motd 5 125message: 126.Pp 127.Dl # jexec -l name login -f root 128.Sh SEE ALSO 129.Xr jail_attach 2 , 130.Xr jail 8 , 131.Xr jls 8 132.Sh HISTORY 133The 134.Nm 135utility was added in 136.Fx 5.1 . 137.Sh BUGS 138If the jail is not identified by 139.Ar jid 140there is a possible race in between the lookup of the jail 141and executing the command inside the jail. 142Giving a 143.Ar jid 144has a similar race as another process can stop the jail and 145start another one after the user looked up the 146.Ar jid . 147