db0f264393
The early environment is typically cleared, so these new options need the PRESERVE_EARLY_KENV kernel config(8) option. These environments are reported as missing by kenv(1) if the option is not present in the running kernel. Reviewed by: imp Differential Revision: https://reviews.freebsd.org/D30835
171 lines
4.2 KiB
Groff
171 lines
4.2 KiB
Groff
.\"-
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.\" Copyright (c) 2000 Peter Wemm <peter@FreeBSD.org>
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHORS AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHORS OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 20, 2021
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.Dt KENV 1
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.Os
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.Sh NAME
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.Nm kenv
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.Nd list or modify the kernel environment
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.Sh SYNOPSIS
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.Nm
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.Op Fl l | s
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.Op Fl hNq
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.Nm
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.Op Fl qv
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.Ar variable Ns Op = Ns Ar value
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.Nm
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.Op Fl q
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.Fl u
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.Ar variable
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.Sh DESCRIPTION
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The
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.Nm
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utility will list all variables in the kernel environment if
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invoked without arguments.
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.Pp
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If the
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.Fl l
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option is specified, then the static environment provided by
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.Xr loader 8
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will be listed instead.
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Similarly, the
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.Fl s
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option will list the static environment defined by the kernel config.
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Both of the
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.Fl l
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and
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.Fl s
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options are dependent on the kernel being configured to preserve early kernel
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environments.
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The default kernel configuration does not preserve these environments.
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.Pp
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If the
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.Fl h
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option is specified, it will limit the report to kernel probe hints.
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If an optional
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.Ar variable
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name is specified,
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.Nm
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will only report that value.
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If the
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.Fl N
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option is specified,
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.Nm
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will only display variable names and not their values.
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If the
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.Fl u
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option is specified,
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.Nm
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will delete the given environment variable.
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If the environment variable is followed by an optional
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.Ar value ,
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.Nm
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will set the environment variable to this value.
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.Pp
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If the
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.Fl q
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option is set, warnings normally printed as a result of being unable to
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perform the requested operation will be suppressed.
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.Pp
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If the
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.Fl v
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option is set, the variable name will be printed out for the
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environment variable in addition to the value when
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.Nm
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is executed with a variable name.
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.Pp
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Variables can be added to the kernel environment using the
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.Pa /boot/loader.conf
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file, or also statically compiled into the kernel using the statement
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.Pp
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.Dl Ic env Ar filename
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.Pp
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in the kernel config file.
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The file can contain lines of the form
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.Pp
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.Dl name = "value" # this is a comment
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.Pp
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where whitespace around
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.Sq name
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and
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.Sq = ,
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and everything after a
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.Sq #
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character, are ignored.
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Almost any printable character except
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.Sq =
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is acceptable as part of a name.
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Quotes are optional and necessary only if the value contains whitespace.
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.Sh EXAMPLES
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Show kernel probe hints variable names and filter for the uart
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device
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.Bd -literal -offset indent
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$ kenv -h -N | grep uart
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hint.uart.0.at
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hint.uart.0.flags
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hint.uart.0.irq
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hint.uart.0.port
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hint.uart.1.at
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hint.uart.1.irq
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hint.uart.1.port
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.Ed
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.Pp
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Show the value of a specific variable:
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.Bd -literal -offset indent
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$ kenv hint.uart.1.at
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isa
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.Ed
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.Pp
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Same as above but adding the name of the variable in the report:
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.Bd -literal -offset indent
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$ kenv -v hint.uart.1.at
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hint.uart.1.at="isa"
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.Ed
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.Pp
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Try to delete a variable and suppress warnings if any:
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.Bd -literal -offset indent
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$ kenv -q -u hint.uart.1.at
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.Ed
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.Pp
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Set the value of the
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.Ev verbose_loading
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variable
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.Bd -literal -offset indent
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$ kenv verbose_loading="YES"
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verbose_loading="YES"
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.Ed
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.Sh SEE ALSO
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.Xr kenv 2 ,
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.Xr config 5 ,
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.Xr loader.conf 5 ,
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.Xr loader 8
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.Sh HISTORY
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The
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.Nm
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utility appeared in
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.Fx 4.1.1 .
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